The present invention describes compositions for disinfection and/or effective preservation of food, for example fresh food, which allows the effective removal of microorganisms from these. The disclosed compositions contain derived extracts from plants with antimicrobial activity, which can act on their own or in combination with other disinfecting agents such as organic acids and chlorine compounds. The compositions of the invention are able to remove microbial contamination, including pathogenic microorganisms in seeds and sprouts obtained therefrom without changing the germination properties and nutritional and/or alimentary properties of the sprouts.

In developing countries, diseases transmitted by food (DTF) represent one of the most important issues regarding public health (Kumate and Isibasi, 1986; Kumate, 1988). DTFs result from a food's lack of innocuousness. This causes outbreaks, mainly of bacterial origin (Archer and Kvenberg, 1985). Vegetables represent an important source of microorganisms. Some of these display pathogenicity towards both humans and animals (Fernández, 2000). Based on this, from earlier times, decrease or elimination of microorganisms has been sought through the use of disinfectants. In spite of advances made in other areas, such as medicine and technology, the diseases associated with food intake still affect most of the world. Worth mentioning within these is those of bacterial origin (Roller, 2003). For instance, in the United States the estimated yearly incidence of diseases produced by food is around 76 million cases, resulting in 325,000 hospitalizations and 5,000 deaths. In England, there are an estimated 76 million cases of infectious intestinal diseases per year, of which only 1.5 million seek medical care (Roller, 2003). The estimated number of cases in Mexico is over 300 million per year (Fernández, 2000). Recently, fresh fruits and vegetables have been involved in numerous disease outbreaks. Epidemiologic studies of these demonstrate the role of fruits and vegetables as pathogen carriers, considered with special interest in the innocuity of minimally processed vegetables to E. coli O157:H7, L. monocytogenes, C. botulinum, Shigella, Salmonella, parasites and virus (Brackett, 1992).
Microorganisms access food through several sources and mechanisms, they can simply survive in them without displaying apparent modifications to the sensory attributes of food. Eventually, sublethal adverse modifications regarding acidity, low or high temperatures, and desiccation, among others, affect the microbial proliferative capacity in food. Once favorable conditions are met (e.g., rehydrating powder milk, defrosting fish), microbial growth is possible if the ecological factors are appropriate. The consequences might be progressive deterioration of food or increased health risk after its consumption (Fernández, 2000). Microorganisms of sanitary interest in food normally include bacteria, fungi, yeast, protozoans, microscopic parasites or both of their egg or larva stages, and some microscopic algae (Fernández, 2000). Specifically in regard to bacteria, indicator microorganisms of sanitary interest include pathogens to humans and those that contribute to food deterioration.
Riley et al. (1983) described and linked enterohemorrhagic E. coli (EHEC) to outbreaks characterized by abdominal pain, aqueous diarrhea with blood, and mild fever. This set of symptoms was termed hemorrhagic colitis (HC) and they are caused by ingesting raw or poorly cooked meat. The bacteria isolated in all cases was E. coli serotype O157:H7. Karmali in 1983 linked it with isolated cases of uremic hemolytic syndrome (UHS) characterized by acute kidney damage, thrombocytopenia and microanglopathic hemolytic anemia, preceded by bloody diarrhea. In stools from these cases an E. coli strain was found that was capable of producing a cytotoxin that displayed activity on Vero cell lines, hence its name "verotoxin" (VT). The strains able to produce this toxin are denominated verotoxigenic E. coli (VTEC) (Rodriguez-Ángeles, 2002). This E. coli serotype displays an attractive growth between 30 and 41° C. (Doyle and Shoeni, 1984), it survives freezing and ultrafreezing and, unlike other pathogens, it slowly grows at 6° C. in both meat and raw milk. This serotype survives both the fermentation and drying processes in sausages (Glass et al., 1992). When food is kept at low temperatures, its tolerance to acidic environments is more evident. For instance, in apple cider this germ survives less than 3 days at 25° C., but up to 31 days at 8° C. (Zhao et al., 1993).
E. coli O157:H7 can be found in bovines, goats, sheep, and less frequently in pigs and chickens, although their main reservoir is the intestine of bovine cattle. The microorganism has also been isolated from fruits and vegetables such as lettuce, radish, alfalfa, and from other commercial products such as mayonnaise and non-pasteurized orange and apple juices. Even if these foods have a pH value of 3.4, this bacteria is able to survive for several days in such conditions (Rodriguez-Ángeles, 2002). E. coli O157:H7 is transmitted through ingestion of raw or poorly cooked meat, raw milk or contaminated water. Transmission also occurs between individuals or as a consequence of food handling. Some studies suggest the importance of the domestic fly as a factor in the E. coli O157:H7 transmission process (Rodriguez-Ángeles, 2002).
Salmonella sp is a typical Gram-negative rod from the Enterobacteriaceae family. They are generally mobile, aerobes, or facultative anarobes (Fernández, 2000). Salmonella sp grows well at room temperature even if its optimal growth temperature is approximately 37° C. Its pH growth range is between 4.1 and 9.0. Their minimal growth aw is variable depending on the food, although it is approximately 0.93-0.95 (Frazier and Westhoff, 1993).
In Salmonella sp outbreaks there are a several types of food implicated. Different types of meat are frequently implicated, for instance poultry and its derivatives, especially if they are kept without freezing for a long time. Fresh meat might contain bacteria of the Salmonella genus that previously caused a disease in the sacrificed animals, or they were acquired during its handling. Milk and dairy products, including fresh milk, fermented milk, ice cream and cheese, have been known to cause Salmonella infections (Frazier and Westhoff, 1993). Chicken eggs are a prominent carrier during salmonellosis transmission (Doyle and Ellin, 2000). Vegetables grown in soil irrigated with sewage water, or grown near breeding or domestic animals, or those that are fertilized with animal wastes, are frequently contaminated with pathogenic agents, including Salmonella sp. Foods used for animal breeding are an especially significant link in the Salmonella cycle. Several of them are obtained from co-products of animal origin (fish meal, feathers, bones, viscera and blood) that generally contain high amounts of pathogenic microorganisms (Morehouse and Wedman, 1961). Bivalve mollusks and other seafood are contaminated with Salmonella because of the pollution from residual waters and coastal waters in which these organisms grow (Mossel and Moreno, 2003). Similarly, some foods containing several Salmonella serotypes can cause the consumer salmonellosis (Mossel and Moreno, 2003). The main symptoms of this gastrointestinal infection are: nausea, vomit, abdominal pain and sudden diarrhea (Frazier and Westhoff, 1993).
Theoretically, any fruit or vegetable might be a carrier of pathogenic bacteria, virus and parasites. Fresh fruits and vegetables are susceptible to microbial attack after harvest because of the loss of their natural resistance and their high content of both water and nutrients (Roller, 2003). Exposed plant surfaces are contaminated by soil, water, residual waters, air and animals, thus microorganisms carried by all of these agents are incorporated as flora. Microorganisms contributed by these contamination sources include pathogens and both primary and opportunist deteriorating agents. From raw vegetables it is possible to recover a wide diversity of pathogenic bacteria. For instance, enteropathogens are more frequent in those grown in land exposed to evident fecal contamination. When contaminated vegetables are not handled with the appropriate hygiene procedures, raw products derived from them might contain pathogenic microorganisms or high amounts of microorganisms derived from feces. Recently, Castro-Rosas et al. (2006) analyzed 170 samples of raw vegetable salads and showed that most of them exhibited high microorganism levels, well above the limits allowed by the sanitary laws in Mexico. Only 9 salad samples were within the limits allowed by this legislation. The survival of intestinal microorganisms in vegetables is high enough to become an important health hazard to the population sector that consumes them in raw forms (Fernández, 2000). Pathogens such as L. monocytogenes and Salmonella sp survive and even multiply outside tomatoes (Fernández, 2000).
Seed Sprouts
Seedlings with dimensions from 1 to 10 cm long are designated as sprouts regardless of their seed of origin. Their metabolism is stimulated by their contact with water, air and warmth. Germination is a set of phenomena or changes produced within the seed that favor the embryo's passage from dormant to active life. Seeds submitted to germination modify their chemical composition and increase their mineral and vitamin contents. Sprouts are better if consumed raw, as cooking destroys most of their nutritional content. The whole sprout can be eaten, including roots and leaves. Sprouts can be consumed alone or they can be added to salads, sandwiches or soups. Beansprouts can be made from different seeds such as wheat, soya, bean, lentil, barley, mustard, and alfalfa, among others. However, those from soya and alfalfa are most commonly consumed worldwide. Among their benefits is their low cost, they can be indefinitely stored, they are easy to grow, and once they sprout their nutritional value increases.
The germination process is simple, cheap, and easy to carry out from a technological point of view. Sprouts are often grown at home without sophisticated techniques or devices, using only some kitchen utensils (Klaus, 1980). For industrial scale production, there are regulations and techniques referring to space disposition, installation, hygiene, production, transport and commercialization (Whyte, 1973). In Mexico and the developing countries these regulations are generally absent, thus they are produced at inadequate sites and in installations with poor hygiene.
There are different methods for seed germination (Whyte, 1973; Klaus, 1980). In all of them they are hydrated until they reach four times their original size or until water saturation. Saturation time varies depending on the type and size of the seed. Once hydrated, excess water is drained and the seeds are placed in a uniform layer within a container in which they germinate at temperatures ranging from 22 to 30° C. and with constant irrigation. Seed sprouts reach a commercially convenient size between 4 and 10 days after hydration. This time depends on the seed type and the germination process employed (Klaus, 1980).
In different countries, once the sprouts have reached the desired size they are usually placed in small polyethylene trays and are covered with plastic film. They are kept refrigerated in this form with a shelf life of 8 days, maximum. In some cases they are packed under modified atmospheres. Chaparro et al. designed a strategy based on the application of the ARPCC system, thus establishing the codex allmentarius. As first measure, some reference terms were defined, the minimal work conditions were established, and these must be considered for seed sprouting. This study concluded that the germination process carries physical, chemical and biological risks, the latter being influential for the process and hence for the innocuousness of germinated seeds.
In Mexico it is common to observe sprouts exposed to the public, often without refrigeration, in public and in supermarkets. Some authors point out that this practice favors sprout contamination with pathogenic microorganisms and promotes the activity of these (Mountey and Wilbour, 1971). Particularly, seedlings are obtained after soya sprout germination. They contain higher amounts of water, vitamins, minerals and enzymes, thus their composition is similar to that of vegetables. A benefit from soya seedlings is their richness in vitamins, especially vitamin C, an important antioxidant. Other vitamins contained in high amounts in this sprout are those of the B, A, E and K groups.
The organism assimilates the proteins from soya sprouts well and their consumption is advised for people with digestion problems. Additionally, as with all sprouts, they contribute to intestinal flora regeneration. Because they are rich in chlorophyll, their consumption is also recommended in anemia cases.
Soya seed sprouts are becoming increasingly known and used. They are refreshing, tender, tasty and easy to prepare. They are widely used in cooking: they are ideal in salads and soups, they are a common ingredient in tomato sauces, and they can be used as an additional ingredient in vegetable sandwiches. They also serve as a decorative element or as a side-dish with rice.
Raw sprout consumption has become a risk factor as it has been found that they contain pathogenic microorganisms such as Salmonella spp, Listeria monocytogenes, Staphylococcus aureus, Aeromonas hydrophila (NACMCF, 1999), Bacillus cereus (Portnoy et al., 1973), Klebsiella pneumoniae, Escherichia coli O157:H7, Shigella and Yersinia enterocolitica (Park at al., 2001). These bacteria might be present in the seed or they contaminate the product during seed germination like that of bean, watercress, mustard and soybean. Some studies show that sprouts support the growth of the pathogenic bacteria mentioned above (Harmon et al., 1987; Beuchat, 1996; Hara Kudo et al., 1997).
It has been demonstrated that pathogenic organisms can exceed 107 CFU/g without negatively affecting the appearance of the sprout. In Thailand, several Salmonella sp serotypes (Lexington, Orion, Senftenberg, Tenn., Poona and Weltevreden) have been isolated from soya sprouts (Fordman et al., 1975).
Similarly, in Mexico some contaminated sprouts have been found to contain a wide variety of pathogenic bacteria, the most prominent being Salmonella (typhi and typhimurium), Shigella (disenteriae and flexinnery), Vibrio cholerae O1 and Escherichia coli strains such as enteropathogen E. coli (EPEC), enterotoxigenic E. coli (ETEC) and enteroinvasive E. coli (EIEC) (Fernández, 1997).
Although the mere presence of a pathogenic microorganism in food is a strong reason to avoid consuming it and also to take preventive measures against an outbreak, any increase in pathogen levels in food promotes the risk of disease. For a pathogenic microorganism to trigger clinical symptoms it must enter into the host at sufficient levels. This is termed the minimal infective dose. Pathogen levels below this value have low probability of triggering disease by food consumption. Conversely, levels close to the minimal infective dose or values well above it increase this probability. Consequently, a food is more or less hazardous depending on the pathogen levels it contains.
Sprouts are found to be a substrate that withstands the growth of pathogenic bacteria. For instance, Salmonella stanley and S. enteritidis actively grow in alfalfa sprouts within the first hours of seedling development (Andrew et al., 1982; Geiges et al., 1990).
Bacillus cereus also increases its numbers at approximately 4 log within the first germination hours (Harmon et al., 1987), similarly to K. pneumoniae (Park and Sanders, 1990; Patterson and Woodburn, 1890). In contrast, Aytac et al. (1994) observed that A. hydrophila and L. monocytogenes do not grow on alfalfa sprouts packed under modified atmospheres and kept in refrigeration for 7 days. There was a slight decrease in both pathogen levels, being more effective against L. monocytogenes. Geisges et al. (1990) reported that L. monocytogenes did not grow in soya sprouts in storage temperatures of 4 and 22° C.
It is important to point out that in studies reporting pathogen multiplication in sprouts, it is the seed used for germination that were contaminated with pathogens. Conversely, when there is no pathogen growth, it is the product that was contaminated. Hence, if sprouts are contaminated with L. monocytogenes or C. botulinum from the seed stage, these pathogens are probably able to increase their numbers similarly to Salmonella or B. cereus. This hypothesis is supported by observations made by Geisges et al. (1990), as they report no growth of S. enteritidis during the storage of soya sprouts. This is not the case for seed germination, in which the microorganism actively grew. Based on this behaviour it is concluded that the microorganism fate in food depends on several factors, such as pH, redox potential, antimicrobial substances, local flora, etc. Similarly, the levels of these factors vary through time, creating favorable or unfavorable conditions for growth of a defined microbial group. In sprouts, if a pathogenic microorganism reaches food when it possesses high levels of native flora, its growth might be inhibited through several mechanisms and even its viability could be affected (Flippin and Mickelson 1960; Gilliland and Speck, 1972; Gilliland and Speck, 1977). Consequently, the activity of pathogens becomes limited. On the contrary, when native flora levels are low (as observed in seeds or during the first hours of germination), pathogens have more opportunities to grow. Additionally, if temperature and humidity conditions are favorable (as those observed during germination and sprout growth) the conditions for microbial growth are met. Therefore, it is possible to state that microbial activity is the highest for both local flora and pathogenic microorganisms during the first hours/days of the germination process and during seedling growth.
In Mexico, sprouts are commonly consumed raw or slightly cooked in soups, salads or mixed with vegetables, thereby increasing the potential of contracting a disease associated with the consumption of these seeds (CDC, 1993). During the 1995-1996 period, 16,481 cases of typhoid fever were reported in Mexico (Sisteena Nacional de vigilancia epidemiológica, 1997). These were possibly associated with the consumption of raw vegetables that were exposed to fecal contamination. It is worth mentioning that sprouts might become contaminated with the use of untreated residual water, thus contributing to the propagation of these diseases (Bryan, 1997).
In 1999, 157 Salmonella spp. outbreaks were detected in the United States which were linked to alfalfa sprout consumption, in spite of the fact that they were treated with a disinfectant based on calcium hypochlorite before their germination (Proctor et al., 2001). In 2001, another Salmonella spp. outbreak was linked to the consumption of the same sprouts, with there being 22 detected cases (Outbreak Alert Database; 2005). Later, in 2004, a Salmonella bovismorbificans outbreak was observed from alfalfa sprouts in which 23 cases were reported. In that same year, an E. coli O157:H7 outbreak linked to the consumption of alfalfa sprouts was registered in a food establishment and 2 cases were registered (Outbreak Alert Database; 2005).
It is worth noting that this information comes from research conducted in countries with strict sanitary control regarding sprout production and commercialization. Thus it can be inferred that, given the inadequate production and commercialization practices in our country, the presence of pathogenic bacteria is higher in our products. Consequently, sprouts are participating in outbreaks and disease cases with increased frequency.
Sprouts are highly susceptible to microbial contamination that can be acquired through different mechanisms and at different stages from its generation to its consumption. Seeds have a variable microbial flora (Park and Sanders, 1990; Patterson and Woodburn, 1980; Piernas and Guiraud, 1997), in part depending on the type of seed, its handling and the treatments to which it is submitted. Its contamination with pathogenic bacteria might originate from the field or from its handling. Contamination may come from the water used to irrigate seedlings, if it is contaminated with pathogenic microorganisms. During food harvest, transport and commercialization, the most important contamination source is apparently human, as in these stages food is frequently in contact with humans. Additional factors that might contribute to a lesser degree are utensils, surfaces and the equipment used for food processing and handling.
Seedlings are some of the vegetables that have been involved in disease outbreaks and mega-outbreaks caused by diverse pathogens during recent years. A wide variety of chemical and physical disinfectants have been evaluated alone or in different combinations. Different disinfection processes have also been tested in seedlings. It has been concluded that an accessible and economical practice is impossible to achieve in order to completely eliminate pathogenic microorganisms in sprouts. There is a problem posed by this type of food: if the seed is contaminated with pathogenic bacteria during its germination, they multiply and colonize the plant forming a biofilm, or impermeable film, that protects them against chemical and physical disinfectants. All this occurs within the first 24 hours of seed germination and seedling development, thus it is practically impossible to eliminate bacteria within the first hours of growth. Consequently, the critical step in sprouts production is limited in order to obtain a seed free from pathogenic bacteria. Nevertheless, up until now an effective disinfectant or disinfection procedure that eliminates pathogenic bacteria from the seed has not been reported. In this regard, several disinfectants and treatments have been examined in extreme cases. For instance, submitting alfalfa seeds to 20,000 mg/L hypochlorite. However, this does not ensure the complete elimination of pathogens as Salmonella sp, whereas a high hypochlorite concentration causes the death of alfalfa seeds.
In order to find an efficient way to ensure microbial safety in seedlings, a wide variety of methods have been investigated (Fett, 2006), including chemical, physical and natural antimicrobial treatments, and a combination of these (Fett and Cooke, 2003).
Among the most common solutions studied as disinfectant agents are sodium and calcium hypochlorite, hydrogen peroxide, ethanol, carbon dioxide, potassium sorbate, calcium propionate, benzoic acid, salicylic acid, and riboflavin, among others (NACMCF, 1999).
Regarding chemical treatments, the current recommendation issued by the U.S. and the Food and Drug Administration to producers of seed sprouts is to use 20,000 mg/L chlorine, Ca(OCl)2 for a maximum period of 15 minutes in order to reduce the risk of pathogenic agents (Rajkowski et al., 2003). This is the only treatment approved by the U.S. Environmental Protection Agency to be used on seed sprouts that reduces but does not eliminate the number of pathogens. Therefore, the potentially surviving microorganisms are still a hazard to consumers. This has been demonstrated by the detection and growth of E. coli O157:H7 in sprouts produced from seeds treated with 20,000 mg/L of free chlorine (Lang et al., 2000).
Generally speaking, disinfection is more effective in seeds in comparison to seedlings. This might be due to the combination of lower levels of microorganisms and organic matter within the seed when compared to sprouts, whereas bacteria internalization within sprout tissue renders them physically inaccessible to sanitizing agents (NACMCF, 1999).
Nowadays, a disinfection process that is more efficient and minimally alters organoleptic properties of the food is radiation. Although it has important limitations because food treated in this manner may not be accepted by the consumer due to the concern of residual radiation. The cost of the equipment and the installations to perform it is also a drawback. Additionally, it has been demonstrated that very low doses such as 1 kGy are enough to inhibit seed germination (Konowalchuk and Speirs, 1974).
Therefore this treatment is applicable to the product, but not the seed. One alternative is the use of chemical germicides. Currently, in several parts of the world an effort is being made to develop and evaluate effective and efficient disinfectants in order to eliminate or minimize the risk posed by the presence of pathogenic microorganisms in food such as raw vegetables and seeds used for sprout production. Recent reports express the interest in evaluating disinfection methods based on physical and chemical agents that allow a seed to be free from pathogenic microorganisms (Beuchat, L. R. 1997; Jaquette et al., 1996; Okuda et al., 1994; Plemas and Guiraud, 1997). Generally, fruits and vegetables are not consumed as soon as they are harvested. In industry (and even at home) they receive several treatments aiming to favor their preservation and/or innocuousness. By applying disinfectants to fruits and vegetables their microbial image improves. Nevertheless, it is difficult to safely achieve microorganism inactivation or removal even in extreme treatment conditions that do not harm the food in a sensory aspect (Fernández, 2000).
The disinfection process refers to the physical destruction of microorganisms with activities that compromise food innocuousness or its sensory properties. This effect can be achieved through physical or chemical means and their effectiveness depends on the microorganism (type and number), the substrate upon which they grow (the presence of organic matter), the material's structure (it should allow the germicide to reach microorganisms) and germicide (concentration, temperature, contact duration) (Fernández, 2000).
During the disinfection process, the germicide substance participates in chemical reactions, thus a higher number of microorganisms requires higher levels of these agents in order to achieve a complete inactivation of the microbial population. Susceptibility towards a specific germicide is variable among microorganisms: some of them are inactivated from their first contact with it, whereas, at the other extreme, some survivors might exist. Finally, it must be taken into account that, among microorganisms the selection of a strain with increasing resistance towards the effect of a specific germicide is possible. Consequently, increasing disinfectant concentrations might be required with time in order to reach the same level of inactivation (Fernández, 2000).
Different studies show that disinfection treatments are often weak or limited. For instance, the treatment of whole tomatoes with 100 mg/L of active chlorine for 2 min is sufficient to inactivate germs such as Salmonella sp that were previously inoculated on the tomatoes' surface (Wei et al., 1995). Washing and disinfecting a commercial product based on grapefruit seeds with 200 mg/L of active chlorine (hypochlorite), iodine (iodophor), ClO2 or 100 mg/L, reduced the content in alfalfa sprouts to just 1-2 log10. The decrease of the previously inoculated S. typhi or V. cholerae O1 was not superior to 1.5 log10 CFU/g (Castro-Rosas and Escartín, 1999).
The food industry has a wide variety of germicide agents. Their virtues and limitations force us to carefully select those that better adjust to each particular need (Fernández, 2000). Germ inactivation in food processing plants is a basic requisite in order to control germs and to keep them from accessing the finished product (Álvarez, 1998). Frequently, a germicide is considered effective when it shows its capacity to inactivate at least 3 Log10 of a microorganism suspension in 30 s (Fernández, 2000).
Chlorine is a cheap disinfectant and it is available as hypochlorite or, alternatively, in its slow release forms (e.g., chloramines) (Lelieveld, 2003). Hypochlorites have a wide spectrum of antibacterial activity, although they are less effective against spores in comparison to bacteria that do not form spores, and they also have a low effect on mycobacteria (Russell y et al., 2004).
Chlorine solutions, such as sodium hypochlorite or chlorine dioxide are widely used by the food industry as disinfectants. Both of them are strong oxidants that act on membranes or other cellular components (Harmon et al., 1987). However, a disadvantage of the former is that it reacts easily with organic matter, thus being rapidly inactivated. There is minimal interference with the latter (Castro-Rosas, 1998). The main disadvantage of sodium hypochlorite is that humidity, heat, light and especially the presence of organic matter increase the loss of free chlorine. The germicide activity has been generally attributed to hypochlorous acid (HOCl), which is generated in aqueous hypochlorite solutions and other chlorine-containing compounds.
Disinfectants can be incorporated into washing water and thus they contribute to microbial load reduction. Hypochlorite effectiveness is not only affected by exposure time and free chlorine concentration, but also by other factors such as temperature, pH, and strain type, as well as the presence and type of organic matter (Álvarez, 1998). It has been observed that by submerging sprouts into 100 and 200 ppm hypochlorite solutions, the presence of Salmonella sp is reduced. However, despite this significant reduction, it was only 1 Log10 (Castro-Rosas and Escartín, 1999). Some authors point out that the efficiency of hypochlorite for reducing the presence of pathogenic microorganisms is limited in vegetables (Adams et al., 1989).
Chemical compounds derived from chlorine, iodine and silver have typically been used as vegetables disinfectants. However, some recent studies show that disinfection treatments using these compounds are inefficient regarding the elimination or decrease of pathogenic microorganism levels.
The use of these chemical additives to delay food deterioration or to preserve their innocuousness is a procedure universally employed by food producers. Nevertheless, some of these antimicrobials might be toxic to consumers. This is the case of the nitrites used on meat products (ham, sausages, processed meat, etc.) as they can form nitrosamines that potentially cause cancer. Another example is hypochlorite solutions (widely used in the food and vegetable industry as well as in the home). However, recent reports show that hypochlorite as a solution might generate carcinogenic precursors. In addition, several of the chemical disinfectants, such as iodine-based solutions or colloidal silver, display limited or variable antimicrobial effects in products such as raw vegetables. A similar situation occurs with food preservatives. Because of this, disinfectants and preservatives obtained from plants have recently appeared as a viable alternative. These might have equal or greater antimicrobial potential, along with minimal risk to consumers.
Organic acids have traditionally been employed as food preservatives. Their antimicrobial effect is caused by their non-dissociated forms that cause a pH decrease.
Acetic acid is an innocuous substance and there are no official limits for its daily intake in humans. When acetic acid is included in food, two effects are displayed: one as an acidifier and another as a preservative. A 1-2% concentration inhibits almost all flora within reasonable elevated limits of initial load. At 0.1% it acts on most pathogens, and sporulated at 0.5% it has effects on toxigenic fungus. Acetic acid efficiency has been evaluated against specific pathogens using food as the test medium (Doores, 1993). The published reports are difficult to compare, as acetic acid concentrations are expressed as percentage, molarity, or final pH of the acidified test medium. Its microbial activity depends on exposure time, dissociation level and pH (Levine and Fellers, 1940).
General results show that acetic acid efficiency increases the higher its concentration, it decreases pH, the temperature increases and the microbial load decreases. Because fungi (yeast and molds) grow at low pH values, they display higher resistance towards acetic acid in comparison to bacteria (Luna, 1983). Among all bacteria, Gram-positive tend to be more resistant when compared to the Gram-negative group (Ray and Sandine, 1992). Bacterial spores and viruses are more resistant in comparison to vegetative cells.
In meat, the antimicrobial potential of acetic acid is evident when applied directly. In products such as mayonnaise, tomato sauces and several seasoned foods based on meat, fish and vegetables, acetic acid is included mainly as a flavouring agent, although it also has a preservative effect. For instance, a Salmonella sp concentration of 6.7 log10 CFU in a salad (pH 3.5-3.7) containing egg, vegetables, oil, cheese and Italian dressing, was reduced to non-detectable levels of pathogens after 10 minutes due to the effect of the vinegar (acetic acid) contained in the salad.
Several countries have abandoned the use of hypochlorite or iodine solutions for food disinfection. Plant-derived components with sufficient antimicrobial activity and low toxicity toward humans, such as cinnamaldehyde, might be good alternatives. It has been demonstrated that treatment of the surface of tomatoes with trans-cinnamaldehyde significantly reduces the number of deteriorating bacteria and fungi (Rahman and Shafiur, 1999).
Garlic extract is applied to fresh fruit to protect it against post-harvest diseases and a complete control has been obtained over brown putrefaction of peaches caused by Monilinia fructicola (Roller, 2003). Yucel and Karapinar (2005) evaluated S. typhimurium decrease in onions through the application of lemon juice, vinegar and mixtures of both, and they observed a reduction of 0.87-2.93, 0.66-2.92 and 0.86-3.24 Log CFU/g, respectively.
In yet another study, Muñoz (2003) evaluated the effect of two carvacrol concentrations and the commercial disinfectant Boradantix© (EVESA, Extractos Vegetales S.A.) on the survival of L. monocytogenes, P. fluorescens, E. coli, Erwinia caratovora and S. typhimurium in lettuce juice and carrots. All microorganisms under study were inhibited at both carvacrol concentrations. The studied bacteria displayed higher sensitivity towards carvacrol when compared to Boradantix©.
Lin et al. (2000) evaluated the effect of allyl- and methyl-isocyanate (AITC/MITC) (key components of mustard greens) on L. monocytogenes, E. coli O157:H7 and S. montevideo inoculated on the surface of lettuce and tomatoes. An 8 Log decrease was achieved on the lettuce by treating them with the vapor generated by 400 μl AITC after 4 and 2 days, respectively. An 8 Log decrease of S. Montevideo was also observed on tomato cuticle with 500 μl AITC.
Andrade (2004) evaluated the effectiveness of several seed-based disinfectants on the damage caused by radical rotting (Gaeumannomyces graminis, tritici var.) of wheat. The results allowed him to assess that active ingredients of the seed (triticonazole, triadimenol and silthiofam) attained the delay and/or decrease caused by this pathogen.
It is common to find substances in food that have an inhibitory effect against some type of germ. At the concentrations at which these substances are generally found in food they display a selective effect, i.e. a particular microorganism is inhibited at different magnitudes when compared to others (Fernández, 2000). Antimicrobial agents can be grouped according to their respective origins, as indicated in Table 1.
TABLE 1Antimicrobial substances in foodsNaturalConstitutiveTerpenes, phenolsGenerated duringHydrogen peroxide, lactic acid, nisin.manufacturingAddedLegallyDirectly: ascorbic acid.Indirectly: gas mixtures.FraudulentCarbon dioxideResidualFrom food generation: penicillin in the milk excretedby udder.During equipment cleaning with germicides
Herbs and spices are widely used in the food industry as flavoring agents and fragrances. However they also display useful antimicrobial and antioxidant properties. Several plant derivatives contain antimicrobial compounds that possess a broad-spectrum activity against bacteria, fungi and mycobacteria. Although 1300 plants have been reported as potential sources of antimicrobial agents, up to this date such alternative compounds have not been sufficiently used in food. In the last 20 years, hundreds of scientific articles have demonstrated the antimicrobial activity of natural compounds against pathogenic and deteriorating microorganisms. However, very few of them have been used in real applications in food (Roller, 2003). Antimicrobial activity of compounds derived from plants against different microorganisms has been individually assayed in vitro and they are well documented in references. (Tables 2 and 3) (Roller, 2003; Jongen, 2005).
TABLE 2Plants with antibacterial activityAnnatto, basil, almond (bitter, sweet), anethole, angelica, anise,asafetida (Ferula sp.), birch, absinth, garlic, star anise, piper,musk, celery, tea tree, artemisia(Artemisia vulgaris), bergamot.Cajeput, calamus, cananga, cardamom, husk of the hassaku fruit, onion,cedar, sagebrush (Artemisia tridentata), chilli, cinnamon, citronella,clove, coriander, cortuk (Echinophora sibthorpiana Guss.), cumin,tumeric, cymbopogon.Dill, helenium, tarragon, eucalyptus.Flowers from the bitter orange tree, lima flower.Sweet gale, gardenia, geranium, gaultheria, lentiscus tree gum.Mint, fennel, incense,Jasmine, ginger.Laurel, lavender, lemon, lime, lovage.Mandarin orange, german chamomile, marjoram, melissa,Mentha suaveolens, mustard.Orange, nutmeg.Ocimum, onagra, oregano.Reference: Roller, 2003
TABLE 3Some natural antimicrobial compounds in plantsApigenin-7-O-glucoside, aureptan, benzoic acid, dihydrocaffeic acid,caffeic acid, 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid,5-O-caffeoylquinic acid, cinnamic acid, chlorogenic acid, ferullicacid, gallic acid, 4-hydroxybenzoic acid, 4-hydroxycinnamic acid,3-methoxybenzoic acid, protocatechuic acid, 3,4,5-trimethoxybenzoicacid, 3,4,5-trihydroxyphenylacetic acid, vanillic acid.Berbaman, berberine, borneol.Caffeine, camphene, camphor, carnosol, carnosic acid, carvacrol,caryophyillene, catechin, cineol, cinnamaldehyde, citral, chicorin,columbamine, coumarin, p-coumaric acid, o-coumaric, p-cymene,cinarin.Dimethyl oleuropein.Esculin, eugenol.Geraniol, gingerol.Humulone, hydroxytyrosol.Isovanillic, isoborneol.Linalool, lupulone, luteolin 5-glucoside, ligustroside, S-limonene.Myricetin, menthol, menthofuran.OleuropeinParadols, o-pyrocatecuin, alpha-pinene, beta-pinene, pulegoneQuercetinRutin, resorcylicSalicylaldehyde, sesamol, shogaols, syringic acid, sinapic.Tannins, thymol, tyrosol.Verbascoside, vanillin.Reference: Roller, 2003
Plants produce a variety of chemical compounds with antimicrobial activity. Some of them are natural components of the plant and others are produced in response to physical lesions as they allow an enzyme-substrate interaction, and some others (phytoalexins) are produced in response to microbial invasion. These compounds are lethal to microbial cells, or they can simply inhibit the production of a specific metabolite (e.g., mycotoxin). The protective role they fulfill in the plant and their potential as an antimicrobial in food has been a subject of interest to many researchers (Jongen, 2005).
In vitro studies show that almost every essential oil from herbs and spices inhibit microbial growth as well as toxin production. Antimicrobial effect is dependent on the concentration and it can be a strong bactericide at high concentrations. Several Gram-positive, Gram-negative, yeast and fungi are affected by a wide variety of essential oils from plants. Well known examples include essential oils from English pepper, almond, laurel, black pepper, cinnamon, caraway, clove, coriander, cumin, garlic, grapefruit, lemon, nutmeg, mandarin orange, onion, orange, oregano, rosemary, sage and thyme (Roller, 2003).
Thyme essential oils (Thymus genus) have been tested on different microorganisms. 200-250 ppm concentrations of T. capitatus (the most common thyme) completely inhibited the growth of Penicillium italicum, Penicillium digitatum, Botrytis cinerea, Altenaria citri, Altenaria alternata, Fusarium oxysporum and Rhizopus stolonifer.
Using extracts from Thymus vulgaris, B. cinerea and R. stolonifer were inhibited by 50% (Roller, 2003). Carvacrol has been identified as the substance responsible for antimicrobial activity in T. capitatus essential oils. Thymol, carvacrol and linalool are active agents in T. vulgaris. However, other components at lower levels might also contribute in a synergistic manner to the antimicrobial activity of a given essential oil. A marked synergism between nisin and carvacrol has been registered as bactericide and bacteriostatic against B. cereus and L. monocytogenes (Roller, 2003). Essential oils (EO) in oregano (Origanum spp.) contain thymol and carvacrol and they have both been known as very active agents against several mycotoxigenic fungi and to some citrus disease-inducing agents.
Among the complex components contained in EO from citrus fruits, the citral terpene (3,7-dimethiyl-2,6-octadienal) is known to have strong antifungal properties. Recent studies in vitro demonstrated that citral inhibits P. expansum, P italicum and P. digitatum, all of them identified as responsible for severe putrefaction during the storage of apples and citrus fruits, However, due to its toxicity, citral might be difficult to use in fresh fruits and vegetables (Roller, 2003).
In several studies, plant extracts have been used to extend the shelf life of food (Jongen, 2005). Extracts from some garlic species inhibit in vitro growth the of Aspergillus parasiticus, A. niger, A. flavus and A. fumigatus among many others, all of them being fungi that contribute to the deterioration of grains, vegetables and processed foods. The synergism between nisin and aqueous garlic extract for inhibiting L. monocytogenes has been described previously. In general, garlic extract activity decreases during storage and upon heating. Raw aqueous extracts are more active in comparison to ethyl acetate, ether, chloroform and ethanol extracts (Roller, 2003).
Red beet juice displays a slight antimicrobial activity against E. coli pathogenic groups: enteroinvasive, enteropathogen and enterotoxigenic, and also to S. typhimurium (Ramírez, 2006). In a study performed with 19 aqueous extracts from the leaves of local plants in our country, 8 of them displayed activity against Rhizopus stolonifer sporulation. Three of these extracts (Annona cherimola M., Bromelia hemisphaerica L. and Carica papaya L.) were also active against R. stolonifer in plums (Spondias purpurea L.). Extracts from Aloe vera pulp have been tested in vitro against the pathogens commonly observed during harvest; P. digitatum, P. expansum, B. cinerea, and Alternaria alternata, the first and the latter being the most sensitive. Aqueous extracts from the leaves of Azadirachta indica, Adv. Juss., Datura fistulosa L., Muraya exotica L., Lantana camara L., Ocimum sanctum L. and Catharantes roseus L. almost completely inhibited the diseases caused by Fusarium scirpi and Helminthosporium spiciferum in Luffa cylindrica L. when they were applied after pathogen infection (Roller, 2003). Extracts obtained from Euphorbia macroclada Boiss stem, flower and leaves were tested in vitro against plant pathogenic fungi, including pre-harvest pathogens. The highest activity detected was against R. stolonifer, and the lowest against A. solani (Jongen, 2005).
There have been relatively few studies regarding the antimicrobial action of essential oils using food system models and real food (Table 4). However, the effectiveness of essential oils in vitro is commonly much better when compared to in vivo or in situ situations, i.e. in food. For instance, mint (Mentha piperita) essential oil has been proven to inhibit Salmonella enteritidis and Listeria monocytogenes growth in culture media for 2 days at 30° C. However, the effect of this essential oil on the Greek appetizers tzatziki (pH 4.5), taramasalata (pH 5.0) and pâté (pH 6.8) at 4° C. and 10° C., was variable (Roller, 2003). Salmonella enteritidis was eliminated in appetizers at all conditions tested but not when it was inoculated in pâté kept at 10° C. In this same study L. monocytogenes displayed a similar behavior as the microbial count decreased in appetizers, but it had the opposite effect on pâté (Roller, 2003). E. coli, Salmonella spp., L. monocytogenes and Staphylococcus aureus growth was inhibited by oregano essential oil in culture broth. However, when these oils were tested on foods such as eggplant, taramasalata and mayonnaise, some reactions were observed, such as pH increase, temperature increase and, in the case of emulsions, a phase separation of the employed oil (Roller, 2003). In another study, L. monocytogenes and S. typhimurium were inhibited in meat treated with clove essential oil and oregano, respectively. A marked decrease of Aeromonas hydrophilea has also been reported in cooked pork meat treated with clove or coriander oils, either vacuum- or air-packed, and stored at 2° C. and 10° C. (Roller, 2003).
The observed differences between studies, regarding antimicrobial effect when plant-derived oils are directly applied to microorganisms (in aqueous suspension) and those employing food or organic matter, might be due to interference from food components or from the organic matter itself (proteins, fats, sugars, salts). Therefore it is possible that a small fraction of the essential oil added to food has antibacterial activity. Conversely, space distribution of the different phases (solid/liquid) in food, the lack of homogenous pH or aw, among other factors, may have a role in effectiveness.
TABLE 4Examples of essential oil application in foodFoodMicroorganismEssential oilMilk (fresh, without cream)S. aureusLentiscus gumSalmonella enteritidisP. frangiDairy products: soft cheese,L. monocytogenesClove, cinnamon, thymemozzarella.Salmonella enteritidisFresh meat: whole or groundSalmonella typhimurium andOregano, clove, basil, sageenteritidisS. aureusP. frangiL. monocytogenesLactic acid bacteriaB. thermosphactaEnterobacteriaceaeYeastLocal floraMeat products: pateL. monocytogenesMintSalmonella enteritidisLocal floraSausageB. thermosphactaMustard oilE. coliFish: golden snapperSalmonella enteritidisOreganoS. aureusLocal floraCod fillet, salmonPhotobacterium phosphoreumBasil, laurel, cinnamon, clove,cymbopogon, marjoram,oregano, sage, thymeSalads and preparations: tuna,S. aureusMint, oregano, basil, sageeggplant, taramasalata,Salmonella enteritidismayonnaise, tzatziki.P. frangiL. monocytogenesS. putrefaciensB. thermosphactaE. coliLocal floraSauces: meat sauceSalmonella enteritidis andBasil, sagetyphimuriumS. aureusP. frangi
Due to this, in several parts of the world a number of studies are being carried out searching for alternative antimicrobials (Jongen, 2005). Among the new disinfectant alternatives, natural compounds with a wide antimicrobial capacity have been selected.
It is noteworthy that extracts obtained from some plants have displayed antimicrobial effects against strains carrying antibiotic multiresistance, thus opening a whole new field for antimicrobial development for human and animal consumption.
Recently, it has been reported that hibiscus flower calyxes (Hibiscus sabdariffa L.) possess substances with high antimicrobial potency (Aziz et al., 1998; Che-Yi and Mei-Chin, 2009; Fernández et al., 1996; García at al., 2006; Kang et al., 2007; Keh-sen at al., 2005; Metwali, 2003). In our work group the antimicrobial effect of nearly 50 different plants commonly used in herbal medicine has been evaluated. Some of them have displayed a high antimicrobial potency against different pathogenic microorganisms, such as Salmonella sp, and Escherichia coli O157:H7, among others. This effect includes food deteriorating microorganisms (e.g. Pseudomonas aeruginosas). In some cases the antimicrobial effect is more significant in comparison to commercial disinfectants based on hypochlorite, Iodine, colloidal silver, or even antibiotics such as penicillin. Several solutions and powders have been obtained from plant extracts displaying the highest antimicrobial effect and their antimicrobial potential has been evaluated. Solutions have been tested on fruits and vegetables contaminated with pathogenic bacteria, whereas powders have been incorporated into several foods, e.g. cheese and cold cuts. Results from these studies show a significant decrease in concentration of all studied bacteria in all of the foods evaluated that have been in contact with solutions or powders derived from plants.
Hibiscus is one of several plants in which the presence of antimicrobial compounds has been reported in their dehydrated calyxes (Fernández at al., 1996; Aziz et al., 1998; Keh-sen et al., 2005; Metwali, 2003; García et al., 2006; Kang et al., 2007; Olaleye 2007; Che-Yi and Mei-Chin, 2009; Wong et al., 2010). Antimicrobial properties contained in plants are affected by several factors such as genotype, environment, harvest season, storage, substance extraction procedures, geographical location, and altitude, among others (Brandi et al., 2006). Consequently, the comparison of results becomes more difficult.
Several phytochemicals with antimicrobial properties have been detected in hibiscus flowers, such as polyphenols (Tajkarimi et al., 2010) and, among them, some phenolic acids (Beuchat, 2001), as well as flavonoids (Cushnie and Lamb, 2005), catechins, and epicatechins (Ikigai et al., 1993; Friedman, 2007; Kuete et al., 2008).
Several patent documents describe hibiscus (Hibiscus sabdariffa) flower extracts and their use as a material with antimicrobial properties.
For instance, patent application JP2002128602 describes its use in an agrochemical composition employed to protect plants in fields, whereas the US20100323046 application describes the use of the hibiscus flower raw extract to produce a medication for urinary infection treatment caused by Escherichia coli and Candida albicans.
In patent application KR20080092186 it is described that a hibiscus extract is used to improve the quality of beef, pork and chicken meat, and also to increase their storage stability. The extract is prepared through ethanol extraction and is submitted to a freeze-drying process. Extract concentration in this composition is 500 mg/ml, whereas meat is treated with a preparation at 0.5-3.0% (per weight).
On the other hand, the US20120015062 application describes two compositions containing extracts from the plant Agapanthus africanus and other compositions containing this and other extracts from different plants, e.g. plants from the Rose family or from alfalfa. These are used as biologic agents to protect other plants, including their seeds. Despite this application document referring to the article published by Leksomboon et al. (Kasetsart, Journal of Natural Science 35: 392-396, 2001), in which it is mentioned that extracts obtained from several plants (Hibiscus sabdariffa, Psidium guctjava, Punica granatum, Spondias pinnata and Tamarindus indica) have antimicrobial function, no experimental evidence is shown that involves Hibiscus sabdariffa extracts in the same applications as Agapanthus africanus.
Based on this, it is necessary to have effective antimicrobial compositions in order to avoid and/or counteract microbial contamination of food, especially that which is consumed raw, sprouts for instance. The aim is to preserve and consume it, without the risk of contracting diseases caused by its contamination with microorganisms.

Phytochemical compositions used as disinfectants and preservatives for food

Universidad Autonoma del Estado de Hidalgo


A folding knife includes a handle having a distal portion and a proximal portion, and a blade rotatably connected to the distal portion of the handle. The blade may be moveable between an opened position and a closed position, and may have at least one lock member receiving recess formed therein. The folding knife may further include a lock bar pivotally connected to a medial portion of the handle and moveable between an engaged position and a disengaged position. The lock bar may include a lock member which contacts a respective portion of the blade adjacent the lock member receiving recess to define a contact point between the lock member and the blade when the blade is in the opened position and the lock bar is in the engaged position. The folding knife may also include a lock pin connected to the handle adjacent the lock member.

A folding knife may generally include a lock mechanism to keep the blade of the knife in a locked position when open. This may be helpful to reduce the possibility of the blade accidentally closing on a user's hand during use. For example, U.S. Pat. No. 5,826,340 to Hull discloses a traditional lock mechanism for a folding knife.
The knife includes a lock bar that is pivotally connected to a handle, adjacent the blade. The lock bar includes one lock member, and the blade includes a lock member receiving recess. The lock member includes a bottom wall, and two sidewalls that extend upwardly therefrom. The lock member receiving recess is defined by a bottom wall, and a pair of opposing sidewalls that extend upwardly therefrom. When the blade is in an opened position, the opposing sidewalls of the lock member matingly engage the respective opposing sidewalls of the lock member receiving recess. In other words, when the blade is in the opened position, respective surfaces of the lock member and the lock member receiving recess are in contact with one another.
This type of lock mechanism may, however, be prone to accidental unlocking by the user. Another problem that may occur with this type of lock mechanism is lock failure when a force is applied to a distal portion of the blade.
Another type of folding knife is illustrated in U.S. Pat. No. 5,615,484 to Pittman. This type of folding knife includes a lock mechanism having a stop pin and a slide member that engages the stop pin. When the blade is in the opened position, the stop pin contacts a notch formed in the end of the blade. The stop pin also contacts a sidewall of the slide member when the blade is in the opened position, and the slide member is in an engaged position. To return the blade to the closed position, the slide member is disengaged from contact with the stop pin, allowing the blade to be freely closed. This type of lock mechanism may also be disadvantageous because it may be prone to accidental unlocking by the user.

Locking folding knife and associated methods


A dishwasher for treating dishes according to a cycle of operation includes a tub at least partially defining a treating chamber, a manifold, a rotatable sprayer that is rotatable about a rotation axis and has an inlet and multiple nozzles collectively forming an outlet and a bushing creating a sealing interface between the manifold and the rotatable sprayer.

Contemporary automatic dishwashers for use in a typical household include a tub and at least one rack or basket for supporting soiled dishes within the tub. At least an upper rack and a lower rack for holding dishes to be cleaned are typically provided within the treating chamber. A silverware basket for holding utensils, silverware, etc. is also usually provided and normally removably mounts to the door or within the lower rack.
A spraying system can be provided for recirculating liquid throughout the tub to remove soils from the dishes. The spraying system can include various sprayers, including one or more rotatable tube wash systems. Powering and driving the rotation in a tube wash manifold can be a significant contributor to the cost and complexity of the wash system within a dishwasher.

Dishwasher with hydraulically powered wash system


A piezoelectric accelerometer comprising a housing with two complementary parts (2005, 2006) in which a metal mass (2002) and an abutting piezoelectric element (2003) movably mounted in place are sandwiched between two conductive contact elements (2001, 2004), wherein the metal mass (2002) is in intimate contact with the piezoelectric element (2003) and the two conductive contact elements (2001, 2004) act as the electric terminals for connecting the accelerometer to any external electronic circuit for further processing.

It is well known that across the terminals of a piezoelectric element a voltage can be induced when a pressure is applied thereto. In this connection, a basic piezoelectric accelerometer can be further constituted by comprising a piezoelectric element to which two wires being soldered whereby forming the terminals for connection with an electronic signal processing circuit for further processing; and a housing having a chamber in which the piezoelectric element is mounted. A disadvantage thereof is that the mass of such a piezoelectric element is relatively small, thereby the voltage produced therefrom is inadequate for further processing and a relatively high acceleration is required.
Further, the heat from soldering of the wires and the size of the solder joints could adversely affect the characteristics of the piezo and such an accelerometer can be only used at temperature lower than the melting point of the solder, thereby it is unreliable and of limited use.


A steam turbine having a steam supplementing structure and an operating method therefor. The steam turbine includes an outer casing and an inner casing, a rotor having a thrust balancing piston, the rotor being rotatably mounted inside the inner casing; and a steam flow channel formed between the inner casing and the rotor. Impeller blades fitted with the rotor and a plurality of guide blades fitted with the inner casing are alternately arranged to form multiple stages of blade groups. Steam is fed from the steam throughflow downstream of a first designated blade staging in multiple stages of blade groups to a thrust balancing piston chamber disposed between the inner casing and the thrust balancing piston of the rotor. An interlayer for the steam to circulate is formed between the inner casing and the outer casing, the interlayer including a supplemental steam chamber which can receive the steam from a sealed chamber between the rotor and the inner casing. The steam is mixed with supplemental steam fed into the steam supplementing chamber via steam supplementing pipelines. The mixed steam then returns, via the communicating pipe in the inner casing, to the steam throughflow downstream of the second designated blade staging in the flow channel.

A steam turbine is a rotary steam-powered machine, customarily comprising a rotatably mounted rotor fitted with blades, the rotor being installed inside a casing shell. When heated and pressurized steam is flowing through a flow space formed by the casing shell, the rotor is set in rotation via the blades.
For reasons of efficiency, operating parameters (e.g., steam pressure and steam temperature) of the steam turbine become increasingly high; however, heat resistance property of the steam turbine is limited by the strength and material of its component parts. To guarantee reliable operation at an especially high temperature, the component parts need to be cooled individually. Without efficient cooling in the case of temperature rise, the component parts have to be manufactured with significantly more expensive materials (for example, nickel-based alloys).
In the hitherto known cooling methods, especially for the component parts (such as casing or rotor) of the steam turbine, a distinction is to be made between an active cooling and a passive cooling. In the case of active cooling, the cooling is effectuated by a cooling medium which is fed separately (i.e., in addition to a working medium) to the component parts. In contrast, the passive cooling takes place purely by means of a suitable guiding or by application of the working medium. Up to now, the component parts of conventional steam turbines have been preferably passively cooled.
The patent CN200580033477.9 discloses a steam turbine (as shown in FIG. 1), wherein the steam turbine comprises: an outer casing 2 and an inner casing 3, wherein the outer casing 2 and the inner casing 3 are provided with a live steam feed channel 10; and a rotor 5 rotatably mounted inside the inner casing 3, the rotor 5 having a thrust balancing piston 4 and comprising a plurality of impeller blades 7; wherein a plurality of guide blades 8 are arranged on the inner casing 3 in such a manner that the plurality of guide blades 8 form, in a flow direction 11, a steam flow channel 9 comprising one or more blade stages; after traversing one blade stage, the steam flows through a return channel 14 within the inner casing 3 into a chamber 15 between the inner casing 3 and the outer casing 2, and then from the chamber 15, flows through a feed channel 16 within the inner casing 3 into a thrust balancing piston antechamber 12 that is disposed in an axial direction 17 between the thrust balancing piston 4 and the inner casing 3; and wherein thrust balance is achieved via the steam in the thrust balancing piston antechamber 12.
The live steam feed is shown symbolically by the arrow 13; the live steam admitted into the live steam feed channel 10 flows for the most part along the flow direction into the flow channel 9, while a smaller part flows as leakage steam into a sealed chamber 18 disposed between the rotor 5 and the inner casing 3. In this case, the leakage steam flows substantially along a counter direction 19. The steam in the sealed chamber 18 flows through a cross-return channel 20 arranged in the inner casing 3 into an inflow cavity 26 which is disposed downstream of one blade stage, wherein symbols 21, 22 represent two turns of the cross-return channel 20; meanwhile, supplemental steam flows into the inflow cavity 26 via a load inlet pipe 23 which extends through the outer casing 2 and the inner casing 3. The return channel 14, after traversing one return blade stage 24, is connected to the flow channel 9; and the cross-return channel 20, after traversing one cross-return blade stage 25, is connected to the flow channel 9, wherein the cross-return blade stage 25 is disposed downstream of the return blade stage 24 along the flow direction 11 of the flow channel 9.
In a practical application of the steam turbine having the cooling structure described above, as shown in FIG. 2, the steam supplementing pipeline 24′ and the cross-return channel 20′ are connected in the inner casing 3′ via a steam supplementing chamber 27′; meanwhile, supplemental steam and cooling steam are fed into the steam throughflow via the pipeline 23′. Such s structure usually causes a serious vibration problem in practical operations. As shown in FIG. 3, the supplemented steam to the steam turbine is directly admitted through the steam supplementing pipeline 24′ into the inner casing 3′ via two lines of inserted tubes from two sides of the steam turbine; thanks to the split structure of the inner casing, the two lines of supplemental steam are separately admitted into two independent steam supplementing chambers 27′ of the inner casing 3′. However, as the ball cavity structure of the steam supplementing valve is designed differently from the pipelines at two sides, throughput and pressure differentials exist between the two lines of supplemental steam, resulting in occurrence of excitation and inhomogeneous throughput of the supplemental steam in the pipelines 23′ at the two sides and in the steam throughflow, thereby causing steam turbine vibration.
The patent CN201480046503.0 discloses the cause for the vibration and provides a solution of additionally mounting a regulation valve and a vibration detection sensor respectively to the steam supplementing pipelines at both sides. As shown in FIG. 5, a first valve 33 and a second valve 34 are respectively provided for the two steam supply pipelines 35, 36 of the steam turbine 32, such that when the first valve 33 and/or the second valve 34 vibrate, the first valve 33 is regulated toward the Close direction, and the second valve 34 is regulated toward the Open position.

Steam turbine having a steam supplementing structure and operating method therefor

SHANGHAI ELECTRIC POWER GENERATION EQUIPMENT CO., ETD.


A surgical system including an expandable device is provided, including an inflatable body and a compliant sleeve. The compliant sleeve includes a distal end, a proximal end, and a cavity extending from the proximal end to the oppositely disposed distal end configured to receive a portion of the inflatable body. The cavity is defined by an inner wall and an outer wall of the compliant sleeve. The distal end of the compliant sleeve forms a closed portion of the cavity and the proximal end includes an opening.

Height loss is commonly associated with spinal fractures, typically referred to as vertebral compression fractures. A large segment of osteoporotic patients experience vertebral compression fractures, with an estimated 700,000 such fractures occurring annually. Kyphoplasty is a minimally invasive procedure that is used to treat vertebral compression fractures using a combination of vertebroplasty utilizing bone cement with balloon catheter technology. The kyphoplasty procedure restores height of the collapsed spinal bone, which diminishes associated back pain.
In a kyphoplasty procedure, an inflatable balloon tamp (IBT) is inserted inside a fractured vertebral body. The IBT is inflated to create a cavity that is filled with bone cement to restore height of the vertebral body.
Using conventional kyphoplasty procedures, the bone cement cannot be injected into the vertebral body cavity next to an inflated IBT at high pressure without risking a loss of pressure due to the adjacent IBT rupturing. This restricts the amount of height restoration that can be achieved from the procedure. This disclosure describes an improvement over these prior art technologies.


A user device may be configured to receive information regarding a set of points of interest that have been determined based on behavior information associated with a user of the user device. The information regarding the set of points of interest may indicate geographical locations associated with one or more of the points of interest, of the set of points of interest. The user device may determine a present geographical location associated with the user device; compare the geographical locations associated with the one or more points of interest to the present geographical location associated with the user device; identify, based on the comparing, a particular point of interest, of the set of points of interest, that is within a particular distance of the present geographical location of the user device; and output, via a display device, information regarding the identified particular point of interest.

Navigation devices, such as those that are present in automobiles, may be used to aid users in locating destinations that are of interest to the users. Some such navigation devices may include a display, upon which a map may be displayed. The map may, in some situations, include icons that denote the location of, for example, businesses (e.g., restaurants, gas stations, airports, etc.) or other landmarks.

Personalized navigation information based on user behavior


A gas detector that includes at least one source of infrared radiation, at least two analytical detectors, each analytical detector adapted to provide an output signal indicative of a first gas of interest and positioned to receive radiation from the source of radiation, at least one reference detector adapted to receive radiation of a predetermined wavelength, a sample chamber for receiving a gaseous sample, and an optical path length disposed between the source of radiation and the analytical detectors and passing through the sample chamber.

The present invention relates to increasing the sensitivity of a gas detector.
There is an unending need to improve the sensitivity of analytical methods and apparatus. In the field of gas detection, for example, improving sensitivity can improve accuracy, the ability to detect trace amounts of a gas, the safety of a system, and process quality.
Gas detectors are often used to detect a gas of interest under various conditions and in a variety of environments. Many times it is also necessary to continuously monitor for the presence and amount of a gas in an environment. Often it is desirable that the detector measure the concentration of a gas in an accurate and timely manner
Gas detectors often include a source of radiation, a sample chamber and a detector. Various attempts have been made to increase the sensitivity of gas detectors including increasing the distance between the source of radiation and the detector, which distance is referred to as the "optical path length." Increasing this distance can increase the amount of sample measured, and therefore the sensitivity of the analysis. Theoretically, a larger sample volume will contain a larger number of gas particles, which in turn can increase the sensitivity of the detector.
One way in which the optical path length has been increased has been through the use of reflective mirrors. The use of mirrors can be undesirable, however, because mirrors tend to corrode and accumulate residue over time. As the residue builds up, the amount of radiation reflected from the mirror decreases, which contributes to a decrease in the useful life of the detector. This is particularly true when vapors, such as water vapors, are present in the sample being measured.
Others have attempted to increase the optical path length by physically increasing the length of the sample chamber, which tends to increase the length of the apparatus as a whole. In addition to undesirably increasing the overall bulk of the apparatus, such an arrangement tends to increase the radiation scattering due to the increased distance between the excitation source and the detector.
Increasing the length of the optical path in a gas detector does not necessarily provide a corresponding increase in the amount of energy capable of being measured. To the contrary, increasing the path length often results in diminishing returns in terms of energy. FIG. 1 illustrates the relationship between optical path length and absorption. The increase in absorbance is exponential relative to an increase in optical path length. As the optical path length gets larger, an incremental increase in path length provides a relatively small increase in absorbance, rendering the increase in path length less efficient in terms of absorption. Thus, incrementally increasing the optical path length of the detector becomes an increasingly less efficient means for increasing the amount of measurable energy.
Methods and apparatus for improving the sensitivity of gas detectors are needed. Increasing the sample size and hence sensitivity of gas detectors is particularly desired, particularly where it is desirable to quantify the concentration of the gas of interest.


A switched resonant power amplifier system for ultrasonic transducers is disclosed. The system includes an amplifier that receives and processes a driver output signal for generating a drive signal that is provided to an ultrasonic device for controlling output of the ultrasonic device. An output control circuit receives and processes a signal related to a feedback signal generated by the ultrasonic device and a divider reference signal, and generates a compensated clock signal that is adjusted for at least one of phase and frequency differences between the received feedback signal and the divider reference signal. A compensated drive circuit receives and processes the compensated clock signal for generating the divider reference signal, and for generating the driver output signal.

1. Technical Field
The present disclosure relates to devices for amplifying an input signal and providing an output signal to a surgical instrument. More particularly, the present disclosure relates to a switched resonant ultrasonic power amplifier system for surgical instruments.
2. Background of Related Art
Conventional power amplifier circuits for supplying drive signals to ultrasonic transducers are susceptible to drift and droop in power delivery and variations in frequency when the ultrasonic transducer is exposed to changing loading conditions. Additionally, conventional power amplifier circuits require a relatively large footprint, are not lightweight, have efficiency problems, are generally complex circuits, and require heat sinking to dissipate heat generated during operation. Due to their relatively large size and radiated heat, placement of conventional power amplifier circuits may be problematic in a medical treatment facility. Therefore, a need exists for a power amplifier circuit to supply a drive signal to an ultrasonic transducer and which overcomes the problems of conventional power amplifiers.

Switched resonant ultrasonic power amplifier system


One or more recesses formed in the back of the back rest for the front seat of a tandem seat assembly for mounting a control panel and related chassis therein for passenger control of the communications, entertainment and other systems installed on the vehicle. The control panel may be electrically parallel to the driver's dash board, as well as containing independent systems and controls, thereby providing the capability for the passenger to safely control the intercommunications and entertainment systems of the vehicle.

The motorcycle is becoming a popular form of transportation, due in part to its fuel economy, maneuverability and the ease with which parking space may be found. Present-day motorcycles are also popular as touring vehicles for short and extended vacation travel. This popularity has created a demand for methods to adapt the conventional single rider vehicle so that a companion may be accommodated. These adaptations may be made either at the time of ordering the vehicle or as an after purchase option.
Most motorcycles are originally equipped with a single seat for a single operator, but many motorcycle buyers equip their purchase with seats adapted to accommodate two riders, frequently including a back rest for each position to provide back support for each rider. This modification makes the vehicle more comfortable, and therefore more desirable, for extended use, as for example commuting to work or for touring.
The popularity of the motorcycle, especially one equipped for two or more riders, has created a demand for accessories to make the motorcycle more pleasant to ride. One accessory often added is a communication system, usually consisting of at least a radio to receive commercial broadcasts and an intercommunications system for the driver to communicate with a passenger via crash helmets equipped with microphone and audio systems.
Communications between the driver and passenger on a motorcycle is difficult, due to the wind, vehicle and traffic noise which buffets the riders. This problem has been addressed in several ways, both acoustically and electronically.
U.S. Pat. No. 4,473,130 (Koerber et al.) discloses an approach to enhance communications between riders by use of acoustic channelling, in the manner of a stethoscope conveying sounds to a doctor's or nurse's ears. Koerber discloses how communications between riders is enhanced by the use of such sound-carrying tubes but does not suggest any way that the passenger can influence or control the communications, short of disconnecting the acoustic tubes.
U.S. Pat. No. 4,206,409 (McKinney) discloses the use of an electronic intercommunications system which utilizes electrical wiring connected between two or more helmets. The electronics comprising such a communications system is well known in the art and McKinney teaches that the addition of a take-up reel for the wiring serves to control the slack in the wiring and keep it from presenting a hazard to the riders. McKinney further discloses that the electronic system may be contained in a box suitable for also holding the helmets and the controls for the electronic device. McKinney suggests that the box could be mounted out of the way of the riders, as at the rear of the motorcycle. This places the controls out of the reach of both driver and passenger, requiring them to make any desired adjustments before beginning their journey.
U.S. Pat. No. 3,586,977 (Lustig et al.) discloses how the addition of an electronic package on a belt can allow the riders to enjoy either commercial broadcasts or intercommunications. The electronic device described by Lustig has any controls therefor mounted on the case which is secured to the belt. This places the controls within the reach of the driver and perhaps also within reach of the passenger who must reach around the driver's seat back to operate them. In both cases the operator cannot conveniently see the controls being operated, relying instead on touch and memory to select the desired control.
Each of the cited patents addresses the problems of communications between riders, but none address the question of how to control the communications systems conveniently and safely.
In the present art, the variety of electronic communications systems available to the motorcycle owner is nearly unlimited. Electronic systems for receiving commercial broadcasts or citizen band transmissions, playing prerecorded music and serving also as an intercommunications system are readily available and commonly added to the motorcycle as dealer installed options. The controls for the installed system are placed on the driver's panel, usually located in the space immediately in front of the driver. This requires that all adjustments to volume, channel or subsystem be made by the driver.

Seat-back dashboard for vehicles having tandem seating


An apparatus for displaying a direction for adjusting its height to its appropriate height includes a plurality of light sources, a light receiving portion, and a control unit. The light sources are arranged in the form of a matrix in a display portion of the apparatus and displays the direction as a moving shape by emitting light in turn. The light receiving portion receives an incident beam and outputs a signal corresponding to a height of the incident beam. The control unit controls the light emission of the light sources in accordance with the signal so as to move the shape downward or upward to indicate the appropriate height. The control unit controls the light emission of the light sources so that at least one light source of a group of the light sources is lighted after a predetermined time, shorter than a time during which a human eye can keep an afterimage, after other members of the group were lighted.

1. Field of the Invention
This invention relates to an apparatus for indicating a direction for adjusting the height of the apparatus to an appropriate height (hereinafter the direction is referred to as "the direction of an appropriate height) so as to enable an operator to recognize it visually and dynamically.
2. Description of the Prior Art
In construction of the land readjustment of housing sites or agricultural fields, it is performed to level the ground. For the construction, large-sized construction machines, such as a bulldozer and a crawler, are used, and the ground is dug and moved by means of the blades of the machines so as to achieve a finished surface which conforms to a site plan. In this ground-leveling operation, surveys are made before and during the operation. Places, on which the ground should be banked or from which the ground should be removed, are determined by the survey made before the operation, and the ground-leveling operation is repeatedly performed in accordance with measured values obtained by the survey, which is carried out as occasion demands, during the operation. As a result, the ground is leveled to conform to the site plan.
An example of such a surveying operation is as follows.
First, a surveyor vertically sets a pole at a place to be surveyed. After that, another skilled surveyor collimates the pole with an optical level and reads numerical values indicating the height at the level. This operation is repeatedly performed, and thereby a plurality of places to be surveyed are measured to calculate differences in elevation among the places.
In recent years, however, a surveying operation in which a rotational laser apparatus cooperates with an appropriate-height displaying apparatus has been employed from the viewpoint of the speedup of construction, the reduction of man-hours, and the reduction of labor costs.
The rotational laser apparatus emits a laser beam in a horizontal direction while rotating so as to form a reference plane of the laser beam. The appropriate-height displaying apparatus receives the emitted laser beam, and then displays the direction of a deviation of an appropriate height from the height of the reference plane of the laser beam.
An example of the aforementioned case is shown in FIG. 1. Reference numeral 1 denotes a rotational laser apparatus, and 2 denotes an appropriate-height displaying apparatus. The rotational laser apparatus 1 is fixed on a tripod 3 which is set at a predetermined place K. A reference plane is formed by a laser beam P projected from the rotational laser apparatus 1. The appropriate-height displaying apparatus 2 is fixed on, for example, an attachment pole 6 which is stood on a blade 5 of a bulldozer 4. Thereby, the height from the ground surface of the predetermined place K to the reference plane of the rotational laser apparatus 1 is correlated with the height from the appropriate-height displaying apparatus 2 to an edge 5a of the blade 5. Accordingly, if the construction is carried out such that the appropriate-height displaying apparatus 2 receives a projected laser beam at a position of a predetermined height, the ground leveling operation can be performed at a predetermined ground level.
As shown in FIGS. 2 and 3, the appropriate-height displaying apparatus 2 generally comprises a displaying apparatus body 7, a plurality of light sources 8 for display, a pair of light receiving portions 9, and a control portion disposed inside of the displaying apparatus body 7. In the light sources 8, each three of them makes a set, and sets in the upper, middle, and lower parts of the apparatus body 7 serve as display portions 8a, 8b, 8c, respectively. Electric power to the appropriate-height displaying apparatus 2 is supplied from a battery of the bulldozer 4. Reference numeral 10 denotes a connector for the power source.
In this conventional appropriate-height displaying apparatus 2, the three light sources 8 of the display portion 8a are simultaneously turned on when the appropriate height of the apparatus 2 is greater than its actual height at that moment. On the other hand, the three light sources 8 of the display portion 8c are simultaneously turned on when the appropriate height is lower than the actual height at that moment. The three light sources 8 of the display portion 8b are simultaneously turned on when the appropriate height is equal to the actual height at that moment.
By the conventional appropriate-height displaying apparatus, it is needed to recognize the position of a display portion which is in an ON-state in comparison with the position of display portions which are in an OFF-state in order to determine which of the display portions 8a, 8b, 8c is lighting. Therefore, by the conventional apparatus, disadvantageously, it is impossible to intuitively recognize information on the direction of the appropriate height in comparison with the actual height at that moment.
This disadvantage is not overcome by conspicuously flashing the display of the light sources 8. Nor is the disadvantage overcome by increasing the brightness of light emitted by the light sources 8. As a solution to this, it can be expected to display information on the direction of the appropriate height by the use of signs, such as arrows, or words, such as "up" and "down".
However, these display methods do not enable intuitive recognition of the information on the direction of the appropriate height in comparison with the actual height at that moment because, according to the display methods, the whole of figures or words must be visually recognized in order to judge the direction to adjust the height of the displaying apparatus to the appropriate height. In addition, if the display, which is in a static state and is inconspicuous, is attempted to be made conspicuous, power consumption is enlarged, and thereby another power source provided in a machine body or the like would be required.

Apparatus for displaying an appropriate height