Produced by Larry B. Harrison, Chris Jordan and the Online Distributed Proofreading Team at http://www.pgdp.net (This file was produced from images generously made available by The Internet Archive) Issued January 9, 1909. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF CHEMISTRY--BULLETIN No. 119. H. W. WILEY, Chief of Bureau. EXPERIMENTS ON THE SPOILAGE OF TOMATO KETCHUP. BY A. W. BITTING, INSPECTOR, BUREAU OF CHEMISTRY. [Illustration: Shield of the United States Department of Agriculture] WASHINGTON: GOVERNMENT PRINTING OFFICE. 1909. LETTER OF TRANSMITTAL. U. S. Department of Agriculture, Bureau of Chemistry, _Washington, D. C., July 15, 1908_. Sir: I have the honor to submit for your approval a report made by Inspector Bitting of experimental work on the spoilage of tomato ketchup, the conditions contributing thereto, methods of prevention, the action of preservatives, and the length of time that the product will keep under varying conditions of manufacture and temperature, both before and after opening. Every effort has been made to conduct the work in a practical way, and the results obtained can not fail to be of interest and profit both to the manufacturer and consumer. I recommend that this report be published as Bulletin No. 119 of the Bureau of Chemistry. Respectfully, H. W. Wiley, _Chief_. Hon. James Wilson, _Secretary of Agriculture_. CONTENTS. Page. Introduction 7 Process of manufacture 8 Selection and preparation of stock 9 Pulping 9 Cooking and seasoning 10 Evaporation and finishing 11 Bottling 11 Processing 11 Character of products 12 First-class products 12 Inferior products from âtrimming stockâ 13 Labels 14 Manufacturing experiments without the use of preservatives 15 Outline of experiments 15 Discussion of results 17 Spoilage of ketchup after opening 17 Spoilage of unopened ketchup 20 Spoilage of market brands 20 Sterility of ketchup 21 Experiments with preservatives 22 Sodium benzoate 22 Salt 23 Sugar 23 Spices 24 Water infusions 24 Acetic acid extracts 25 Oil extracts 25 Vinegar and acetic acid 26 Oil 27 Study of Penicillium in ketchup 28 Development 29 Reproduction 29 Growth in ketchup 30 Temperature tests 31 Histological structure of ketchup 33 Microscopical examination of some commercial brands 34 Summary 35 ILLUSTRATIONS. PLATES. Page. PLATE I. Penicillium. Fig. 1.--Conidia, normal growth and in various stages of germination, some with branching hyphÃ¦. Fig. 2.--Conidiophore, showing unusually large development of conidia; from culture in moist chamber 28 II. Cultures from ketchup preserved with sodium benzoate. Fig. 1.--Conidia and hyphÃ¦ from culture in experimental ketchup containing one-sixteenth of 1 per cent of sodium benzoate. Fig. 2.--Conidia and hyphÃ¦ from culture in experimental ketchup containing one-tenth of 1 per cent of sodium benzoate 28 TEXT FIGURES. Fig. 1. A model receiving platform 8 2. Large receiving room showing the sorting belt 9 3. A section of a kitchen showing the copper cookers 10 4. An example of factory practice 12 5. Another factory interior 14 EXPERIMENTS ON THE SPOILAGE OF TOMATO KETCHUP. INTRODUCTION. The tomato, _Lycopersicum esculentum_, is supposed to be native to South or Central America. The large fruits commonly used grow only under cultivation, but the variety with small, spherical fruits, known as _L. cerasiforme_, has been found on the shore of Peru and is considered by De Candolle[A] as belonging to the same species as _L. esculentum_. Though grown extensively in Europe, there is nothing to indicate that it was known there before the discovery of America. The tomato was introduced into China and Japan at a comparatively recent date. De Candolle is of the opinion that the tomato was taken to Europe by the Spaniards from Peru and was later introduced into the United States by Europeans. Tomatoes were brought to Salem, Mass., by an Italian painter in 1802,[B] who is said to have had difficulty in convincing the people that they were edible. They were used in New Orleans in 1812, though as late as 1835 they were sold by the dozen in Boston. After 1840 they came into general use in the Eastern States, but it was later than this before tomatoes were used freely in the Western States, many persons having the impression that, since they belonged to the nightshade family, they must be unwholesome. The extent to which tomatoes are used at the present time shows how completely this prejudice has been overcome. [A] Origin of Cultivated Plants, 1890. [B] Webber, H. J., Yearbook, U. S. Department of Agriculture, 1899. The name _Lycopersicum_ is from two Greek words, meaning a wolf, and a peach, the application of these terms not being apparent; the name of the species, _esculentum_, is from the Latin, meaning eatable. The common name âtomatoâ is of South or Central American origin, and is believed to be the term used in an ancient American dialect to designate the plant,[C] but its meaning is unknown. The English call the tomato âlove apple,â which in French is âpomme dâamour.â [C] U. S. Dept. Agr., Exper. Sta. Record, 1899-1900, 11: 250. The tomato is considered a typical berry, the ovary wall, free from the calyx, forming the fleshy pericarp, which incloses chambers filled with a clear matrix containing the seeds. The fruit measures from 1 to 5 inches in diameter, and is red, pink, or yellow when mature. The plant sports freely, producing many varieties, which differ mainly in the size, shape, and quality of the fruit. The varieties bearing small fruits are _L. cerasiforme_ and _L. pyriforme_, each bearing a two-celled fruit, the former being round, and somewhat larger than a cherry, and the latter pear-shaped. These small tomatoes are used ordinarily for preserves and pickles. The word âketchupâ is adopted in this bulletin as the form which ought to be given preference. The derivation of the term is not definitely known. The spelling âcatchupâ given in some of the leading dictionaries appears to be based on the erroneous idea that the first syllable âketchâ is a colloquial form of âcatch.â Several authorities derive the word from the East Indian or Malayan âkitjap,â because âketchupâ was originally a kind of East Indian pickles. Some give the word a Chinese origin, while others assert that it comes from the Japanese. A majority of the manufacturers employ the word âcatsup,â a spelling for which there does not appear to be any warrant. PROCESS OF MANUFACTURE. [Illustration: Fig. 1.--A model receiving platform.] The making of tomato ketchup consists essentially in reducing tomatoes to pulp, removing the skins, seeds, hard parts, and stems, adding salt, sugar, condiments, and vinegar to suit the taste, and cooking to a proper consistency. The methods and practices of the various manufacturers differ, and the difference between the best and the poorest procedure corresponds to that between the best and the worst ketchup. No single factory has all of the best methods at every step of manufacture. Some perform certain details well and are negligent in others. In some, large amounts of money are spent on equipment to improve a particular point considered advantageous by the trade, while other details essential to the making of a good-keeping ketchup are disregarded. A statement of the best practice as observed at a number of factories, together with some facts obtained from experiments, will be given. SELECTION AND PREPARATION OF STOCK. The tomatoes should be home-grown, of a red variety having the minimum of yellow and purple color, be picked when ripe, and delivered to the factory promptly without mashing. All tomatoes should pass over an inspection table, the rotten and otherwise unfit fruit should be discarded, and the green tomatoes should be returned to crates to ripen. The stems should be removed when the best color is desired, and the tomatoes should be thoroughly washed to remove dirt and mold. Dumping a crate of tomatoes into a hopper of dirty water and playing a gentle spray of water on part of them merely wets the skin and makes them appear bright. [Illustration: Fig. 2.--Large receiving room showing the sorting belt.] PULPING. The clean tomatoes should be conveyed to the steaming tanks and subjected to steam heat until the skins burst and the meat softens. After a short heating the tomatoes should be run through a âcycloneâ where the skins, seeds, etc., are removed and they are rubbed to a pulp. To remove very small particles and fiber, the pulp may be run through a sieving machine at once; or, if ketchup of the smoothest possible kind is to be made, this procedure should be delayed until after the cooking. The pulp is collected in a receiving vat, and only such an amount should be provided in advance as will keep the kettles full, as it is better to stop the tomatoes before going to the washer than to have the pulp stand for some hours. In common practice, however, the pulp is either sent to the cooker at once, or it is allowed to stand and partially separate. If tall casks are used for this separation the solids will rise to the top and the clear watery portion is drawn off at the bottom, or the pulp may be strained through cloth bags. The object of this separation is to secure greater concentration of the solids, retain a brighter color, and shorten the time of cooking. COOKING AND SEASONING. [Illustration: Fig. 3.--A section of a kitchen showing the copper cookers.] The cooking may be done in copper kettles, as shown in figure 3, though these are being superseded by enamel tanks containing silver-plated coils in order to secure the brightest color. By using the latter the discoloration due to the splashing of the contents against the walls of the copper vessel is avoided, and economy of space is secured. Whole or ground spices, or acetic acid or oil extracts of the spices may be added to the pulp in such proportion as the particular brand demands. The spices most used are cloves, cinnamon, mace, and cayenne pepper; but paprika, pepper, mustard, cardamon, coriander, ginger, celery, and allspice are used by some manufacturers. When whole spices are used, it is the practice to suspend them in a cloth bag or a wire basket and to take them out after boiling. They tend to darken the color of the ketchup, a result considered undesirable by some. The ground spices are used sparingly, with the exception of cayenne pepper. The acetic acid extracts of spices are used because they are economical and give a brighter red color than is obtained with the whole spice. The oil extracts produce no discoloration, but they are the most expensive and give an objectionable flavor. Hungarian sweet paprika is now quite largely used and adds to the color as well as to the flavor. Sugar, salt, and vinegar are added in such proportion as may be desired, and in some brands onions and garlic are used. EVAPORATION AND FINISHING. The pulp is evaporated rapidly to such consistency as the grade and price will warrant, the reduction in volume being from 40 to 60 per cent. This is accomplished in about forty-five minutes. The cooking is not continued longer than is necessary, as each minute added to the cooking darkens the finished product. If the pulp has been run through the sieving machine before cooking, the batch may be drawn off into the receiving tank for bottling. If the finishing be done after cooking, the pulp is run into a receiving vat, finished as quickly as possible, and drawn into the tank for bottling. The ketchup may be kept at a high temperature--200Â° to 206Â° F.--in the receiving tank by means of a small steam coil, or it may be drawn to the bottling machine through a steam-jacketed tube. Finishing after cooking yields a slightly smoother ketchup than sieving before cooking; but it necessitates handling, reduces the temperature, and increases the chances of infection. BOTTLING. The bottles should be thoroughly cleaned as ketchup will not keep if placed in bottles which have been merely rinsed to remove the straw; if the ketchup is not to be given an after process the containers should be sterilized. In the experimental work cork stoppers gave the best results and these should be sterilized in a paraffin bath at 250Â° F. PROCESSING. An after treatment or process is given to bottled goods either in a water or steam bath, the important point being that the center of the bottle be raised to the desired degree of heat. If the ketchup is thin this can be effected quickly, but if it is thick and heavy the heat penetrates the ketchup with surprising slowness. In a thin ketchup the temperature may be raised from 140Â° to 190Â° F. in eighteen minutes or less when the surrounding heat is 195Â° F; but in a heavy ketchup it may take an hour or more to accomplish the same result. It is therefore very important that the ketchup be processed immediately after it is corked, before it has time to cool. The rate at which the heating is effected for different goods can be determined by sealing a thermometer in the cork and recording the readings. [Illustration: Fig. 4.--An example of factory practice showing the top row of tanks from which pulp passes by gravity into the cookers, then into the receiver, sieving machine, and final tub ready for the bottling machine or jug filler.] CHARACTER OF PRODUCTS. FIRST-CLASS PRODUCTS. The factory at which the experiments were conducted has sanitary buildings and surroundings, the floors are of concrete for flushing, and the pipes used in conducting the pulp to the kitchens are porcelain-lined to prevent discoloration from the iron and to insure cleanliness. The tubes which carry the ketchup from the kettles to the receiving tank, finishing machine, and bottler are silver-plated. Not all of these measures are necessary to make a good ketchup, but they show the care exercised in making an article of good appearance and of the finest quality. The conditions under which ketchup is made and the care with which the work is done at some of the better factories is equal to that used in the manufacture of any food product. Whole selected fruit is used, cleanliness is maintained at every point, the best grades of spices, vinegar, granulated sugar, and salt are added for flavoring, and the bottles are carefully washed. The ketchup put up under such conditions will have a bright natural color, will remain good as long as the container is unbroken, and will continue in that condition for some time after opening if kept at a fairly cool temperature. INFERIOR PRODUCTS FROM âTRIMMING STOCK.â In contrast with the strictly high-grade product is the great bulk of the ketchup found on the market. The material is not whole ripe tomatoes, but consists of the waste of the canning factory, commonly designated as âtrimming stock,â including the green, moldy, broken, rotten, and generally unusable tomatoes, the skins, cores, and stems from the peeling tables, and the surplus juice from the filling machines, all of which may be allowed to stand during the day and be run through the cyclone in the evening. At the end of the season, the frosted and half-ripe fruits may be used. Part of this material can not be considered âsound fruitâ as contemplated by the food and drugs act. The pulp is put up in barrels, preserved, and allowed to stand, possibly in the sun, until a sufficient quantity has accumulated for shipment. Old ketchup barrels may be used and be none too clean. As a result, it is not uncommon to see an inch or more of pulp in the bottom of a car at the end of shipment, caused by the blowing out of the barrel heads from fermentation. The sanitary condition of the factory may be poor, the handling of the goods be unclean, the spices be the refuse from the spice houses, the sugar be of the cheapest grade, and the bottles be only rinsed or be used without even that precaution. The ketchup is a concoction so heavily spiced with hot spices that the tomato flavor is lost and might as well be anything else. The color is normally dirty brown. Between these two extremes are all grades, those for which whole tomatoes, unsorted, are used, those for which trimming stock is worked up promptly during the canning season, and those made from stock of unknown history. Some manufacturers work under good and some under poor sanitary conditions. There can be no doubt that with proper selection and precaution much of the by-product of the canning factory and large quantities of tomatoes which are unsuitable for canning might be used to advantage in the manufacture of ketchup; but it requires a nicety of practice not generally found at this time. The practice sometimes followed of making some ketchup from whole stock and a large quantity from refuse and using the former for advertising purposes, only serves to emphasize the fact that the goods belong to two distinct classes. One of the uses for a very considerable amount of pulp from refuse stock is the making of sauce for baked beans and other canned goods where the true character can not be observed by the consumer. [Illustration: Fig. 5.--Another factory interior, showing large pulp tanks in the rear, cooking tanks on the right, and process tanks in front containing thousands of bottles of ketchup.] During the season tomatoes come in at times in larger quantities than can be made into ketchup promptly. The surplus must be worked up into pulp for storage and may be stored in barrels or in tin cans. The pulp stored in barrels will not have as good a color as that put into cans, and the ketchup made from either will not be as bright as that made from whole, fresh stock. The pulp put up in barrels is more liable to spoilage than that put up in cans. The difference in the cost of storage by the two methods is not very great, and some large concerns are using the can exclusively instead of the barrel. LABELS. The labels on the ketchup bottles have been improved somewhat in the last year as regards exactness in describing the contents. Formerly, according to the labels, much of the ketchup was made from whole ripe tomatoes. The question was, What became of the enormous amount of ketchup which it was known had been made from âtrimmings?â On this yearâs ketchup the labels make fewer claims, generally merely stating that it is âtomato ketchup,â which is true whether made from whole tomatoes or refuse. The brand is in most cases the guaranty for good quality. It is not safe to judge the quality by the price, for, though usually good quality can not be expected unless the higher price is paid, some of the high-priced ketchup when placed under the microscope has proven to be a very inferior product. The wide labels on the neck of the bottle are objectionable. Some of these are 2 inches in height, and serve to cover the discolored and spoiled ketchup. As spoilage begins usually in the neck of the bottle, it is difficult to see it when the neck is wrapped with a label, and thus it might easily be overlooked until the main body of the ketchup is affected. The bottles which have the widest labels around the neck are usually the ones provided with one or two large labels on the lower part of the bottle, though some bottles have no other label but the one around the neck. As a rule, however, these are narrow, close to the stopper, and unobjectionable. In buying ketchup for experimental purposes it was difficult and sometimes impossible to learn its age, as often the grocer does not know it, and at other times he will not tell. It appeared, however, that often the ketchup had been on the grocerâs shelf or in the warehouse from one to four years. MANUFACTURING EXPERIMENTS WITHOUT THE USE OF PRESERVATIVES. OUTLINE OF THE EXPERIMENTS. During September, 1907, ketchup was made in experimental batches to determine whether it could be manufactured on a commercial scale without the use of preservatives. These experiments were made to determine (1) the keeping quality before opening the container and (2) the length of time the product will keep without spoilage after the bottle is opened. The ketchup was made in a factory in which the conditions of manufacture and all the surroundings were sanitary; whole, ripe tomatoes, the same as used in the regular grade of canned goods, were used and the formula and process were for a mild ketchup giving the maximum of tomato flavor. Each batch consisted of 50 gallons of finished goods, from which 1 gross of pint bottles was retained for observation. The term âregular ketchupâ as used in these experiments means the pulp of fully ripe tomatoes, to which was added granulated sugar, 80-grain, distilled vinegar, table salt, onions, garlic, whole cinnamon, cloves, mace, and ground cayenne pepper. The pulp was cooked in a steam-jacketed copper kettle for forty minutes and reduced about 50 per cent. The finishing was done after cooking. The regular bottles are pint sizes, washed in hot water, rinsed, and then heated to a temperature of 190Â° F. for thirty minutes or more. The sterile bottles referred to in the experiments were placed in a steam chamber for twenty minutes at 230Â° F. The corks were sterilized by a bath in paraffin at about 270Â° F. All of the work was accomplished quickly to insure a smooth, even product with a bright, clean color. Acetic acid extracts and oil extracts of spices were used in such quantities as would give the same amount of spicing as when the whole spices were employed. In all of the following experiments the ketchups discussed were made in September, 1907, and the last examination reported was made ten months later, in July, 1908: _Experiment No. 1._--Regular ketchup was made, but it was reheated after finishing and bottled in sterile bottles at a temperature of 205Â° F. No spoilage has occurred at the end of ten months. _Experiment No. 2._--Regular ketchup was made, and it was bottled immediately after finishing in regular bottles at a temperature of 165Â° F. An after process was given at 190Â° F. for twenty minutes. No spoilage has occurred after ten months. _Experiment No. 3._--Regular ketchup was made, and was bottled in regular bottles at 165Â° F., and given a subsequent process at 190Â° F. for forty minutes. No spoilage has occurred. _Experiment No. 4._--Regular ketchup was made, was bottled in regular bottles at a temperature of 165Â° F., and given an after process at 212Â° F. for twenty minutes. No spoilage has occurred. _Experiment No. 5._--Regular ketchup was made, the same being put up in regular bottles at a temperature of 165Â° F. and given an after process at 212Â° F. for forty minutes. No spoilage has occurred. _Experiment No. 6._--Ketchup was made in which the acetic acid extracts took the place of whole spices, and the bottling was done at a temperature of 165Â° F., no after treatment being given. No spoilage has occurred. _Experiment No. 7._--Ketchup was made in which acetic acid extracts were used, and the bottling was done at a temperature of 165Â° F. in sterile bottles. No after treatment was given and no spoilage has occurred. _Experiment No. 8._--Ketchup was made in which the oil extracts were used instead of regular spices. The bottling was done in regular bottles at a temperature of 165Â° F., no after treatment being given. No spoilage has occurred. _Experiment No. 9._--Ketchup was made in which oil extracts were used instead of whole spices. The bottling was done at 165Â° F. in sterile bottles, no after treatment being given. No spoilage has occurred. _Experiment No. 10._--Regular ketchup was made, but the pulp was run through the sieving or finishing machine before instead of after cooking, the object being to determine the effect upon the character of the goods rather than upon the spoilage. This practice could be followed to advantage in making all except the very finest goods, and would give the same condition for bottling as in experiment No. 1. _Experiment No. 11._--Pulp was made in the usual manner and run into barrels while just below the boiling point. The barrels had been thoroughly washed and then steamed for twenty minutes. As soon as the pulp had cooled slightly the bung was driven in tightly and the barrel was rolled into storage. At the end of sixty days the barrels were opened and the pulp was found to be in good condition. _Experiment No. 12._--Regular ketchup was drawn into 5-gallon jugs which had been sterilized in the same manner as the bottles. These were kept for sixty days and no spoilage occurred. DISCUSSION OF RESULTS. Twelve hundred and ninety-six bottles were shipped from Terre Haute to Lafayette, Ind., and some were reshipped in order to duplicate the conditions in trade. Some were kept in a warm temperature and in strong light, others in a comparatively cool place and in the original shipping cases, in order to duplicate the conditions in the warehouse and grocery store. There has been no spoilage after ten months other than that resulting from four or five cork leaks and neck cracks. These experiments have shown conclusively that ketchup can be put up on a commercial scale and delivered to the consumer in perfect condition without the use of a preservative. It was demonstrated by the first experiment that the goods could be bottled at a high temperature without difficulty, and that subsequent treatment was unnecessary. The after treatment at 190Â° was tried because it had been found in small experiments that, in giving a higher temperature, the internal pressure would cause more or less breakage of bottles or loosening of corks. After treatment is practiced by some who also use a small quantity of preservative as a further precaution. This treatment is continued from two to three hours at the temperature of high pasteurization. The process at 212Â° was given with little breakage, as the bottles used were of good quality. At and above this temperature the breakage may be reduced by either raising the temperature of the ketchup before bottling or applying pressure upon the outside while giving the process. Neither the acetic acid nor the oil extracts showed any advantage over whole spices in their preservative effects, as all kept. The color was slightly improved, but the flavor was impaired, particularly when the oil extracts were used. SPOILAGE OF KETCHUP AFTER OPENING. The question of how long the ketchup should keep after opening the container in order to satisfy the ordinary requirements of consumption was also studied. A local restaurant, serving about two hundred meals and using from one-half to a gallon of ketchup daily, was supplied with the same kind of ketchup used in the experiments, as were also some families. Instructions were given to use the ketchup as they would ordinarily, with the result that none reported any loss from spoilage. To determine how long the ketchup would keep after opening, 8 bottles from each of the first 9 experiments were kept in the kitchen at a temperature of about 72Â° F., 5 were kept in an incubator at a temperature of 95Â° F., 5 were kept in the laboratory at a temperature of about 67Â° F., and 4 were kept in an inclosed porch where the temperature ranged from 30Â° to 60Â° F. This made a total of 198 bottles. No precautions, other than those of ordinary cleanliness, were taken in opening the bottles, as it was desired to determine the keeping properties under conditions of general usage. The first set of bottles was opened November 5, immediately on being received at the laboratory, all of the ketchup having been kept at the factory until the experiment begun in September was completed. The bottles were covered loosely with a metal cap and observed daily, a record being kept of the date and character of spoilage. The results showed that the differences in the time and temperature of processing had little, if any, effect in checking the spoilage; neither did the use of acetic acid or oil extracts. The most important precaution in checking the spoilage after opening seems to be to keep the ketchup cool. This is shown by the average number of days which elapsed before spoilage occurred in the sets kept under different temperature conditions. For those kept in the kitchen the average number of days was six, the minimum three, and the maximum eleven. Those in the incubator kept for an average of five days, with a minimum of two days, and a maximum of eight. Those in the laboratory had an average of eight days, the minimum being four days and the maximum twenty-two. Those kept in the porch lasted on an average twenty-seven days, a minimum of twelve days, and a maximum of fifty-eight. These figures show the definite relation of temperature to spoilage under the conditions of ordinary use. In making the observations, the metal cap was removed each day, but no ketchup was poured off. The spoilage in all cases was due to mold, and usually this formed in the neck of the bottle where the ketchup had splashed, or at the junction of the ketchup with the bottle. The spoilage was recorded as soon as the slightest growth appeared. In actual use if the neck were wiped out when the ketchup had been used and a growth of mold removed on its first appearance with some of the proximate ketchup the time before spoilage occurred could be prolonged. In these experiments the attempt was made to determine how soon growth appeared under the various conditions of temperature named. The unopened bottles of ketchup were kept in a basement room, the temperature of which is fairly constant, being about 70Â° F. This is approximately the condition in a grocery where the ketchup is kept on the shelves. Another set of samples from the run of September, 1907, was opened February 11, 1908, to determine if storing in a warm room before opening had any effect on the length of time preceding spoilage. Four bottles were taken from each of the first 9 experiments to make up each of three sets, one of which was kept in the kitchen, one in the incubator, and one in the porch, making a total of 108 bottles. The average number of days for those kept in the incubator was four, the minimum two, and the maximum six. The average number of days before spoilage in the kitchen was five, the minimum being three and the maximum nine. Those kept in the porch gave an average of twenty-three days, the minimum number being eighteen days and the maximum seventy-three days. Thus it is seen that the ketchup lasted nearly five times as long at a temperature of 30Â° to 60Â° F. as it did at 72Â°; and also that when ketchup is kept in a warm place before opening, spoilage occurs somewhat sooner, the average for the fresh samples opened under the same conditions being one day more with the incubator and kitchen samples and four days more with the porch samples. A third set of bottles of the ketchup was opened on June 6, 1908, or two hundred and sixty-five days after manufacture. They had been kept in a basement at a temperature of about 70Â° F. One set was placed in the incubator at a temperature of 95Â° F., one set in the kitchen at about 82Â° F., and one set in the refrigerator at 46Â° F. The weather was warm and the conditions favorable to the spoilage of fresh foods. The minimum time for spoilage in the incubator was two days, the maximum time four days, and the average time three and two-tenths days. The minimum time in the kitchen was two days, the maximum time six days, and the average time four and four-tenths days. The minimum time in the refrigerator was nine days, the maximum time nineteen days, and the average time thirteen and sixty-six one-hundredths days. These data are grouped in the following table for easier comparison: _Time of spoilage of ketchup at different temperatures after opening._ OPENED ON NOVEMBER 5, 1907, IMMEDIATELY UPON RECEIPT FROM FACTORY; MAXIMUM AGE, FIVE WEEKS. ----------------------------------------------------------------- Place of storage. | Temperature. | Lapse of time before spoilage. | |------------------------------- | | Average. | Minimum. | Maximum. ------------------| |----------+----------+--------- | _Â° F._ | _Days._ | _Days._ | _Days._ Incubator | 95 | 5 | 2 | 8 Kitchen | 72 | 6 | 3 | 11 Laboratory | 67 | 8 | 4 | 22 Porch | 30-60 | 27 | 12 | 58 ----------------------------------------------------------------- KEPT AT 70Â° F. FOR ONE HUNDRED AND FIFTY DAYS BEFORE OPENING ON FEBRUARY 11. ----------------------------------------------------------------- Incubator | 95 | 4 | 2 | 6 Kitchen | 72 | 5 | 3 | 9 Porch | 30-60 | 23 | 18 | 73 ----------------------------------------------------------------- KEPT AT 70Â° F. FOR TWO HUNDRED AND SIXTY-FIVE DAYS BEFORE OPENING ON JUNE 6. ----------------------------------------------------------------- Incubator | 95 | 3.2 | 2 | 4 Kitchen | 82 | 4.4 | 2 | 6 Refrigerator | 46 | 13.66 | 9 | 19 ----------------------------------------------------------------- SPOILAGE OF UNOPENED KETCHUP. Another test was made to determine whether the ketchup would spoil when kept in a warm place, but not opened. Three bottles from each experimental batch were placed in the incubator November 7, 1907, and were kept there until December 23, 1907--forty-six days--and in that time there was no sign of spoilage. They were then opened and kept in the laboratory; the average number of days before spoilage occurred is indicated in the following table: _Average number of days before spoilage of ketchup after opening (kept 46 days at 95Â° before opening)._ --------------------------------------- Experiment No. | Days before spoilage. ---------------+----------------------- 1 | 2â  2 | 4â  3 | 3â  4 | 5 5 | 5â  6 | 4â  7 | 4â  8 | 4â  9 | 3â  --------------------------------------- It will be observed that these samples spoiled in about the same length of time as the bottles opened in February and tested in the incubator, so that similar results were obtained by keeping unopened ketchup one and one-half months at 95Â° F. and keeping it five months at 70Â° F. From the results of the experiments it is evident that the ingredients of the ketchup in the proportions used are not antiseptic, and it is also apparent from the number of organisms found and the rapidity of their multiplication that ketchup is a good, nutritive medium. Yeasts and molds are the predominating organisms, and, as the ketchup is acid and also contains sugar, and these organisms are found on tomatoes in the field, their predominance in the ketchup is explained. SPOILAGE OF MARKET BRANDS. To determine the keeping properties of the ketchup on the market, various brands were obtained from the grocery stores. In the majority of cases nothing was known of the ingredients or methods of manufacture, except what appeared on the labels. No date of manufacture was given, and in some cases the dealers did not know the age of the product. There were 104 bottles of ketchup opened to find out how long they would remain in good condition. These were kept in the laboratory, though the temperature was higher than that at which ketchup should be held. Of the 104 bottles there were 66 without preservative, according to the labels, 46 of which spoiled. Of the 20 which did not spoil, 2 formed crystals of benzoic acid on the covers of glass dishes during evaporation. Of the 39 which, according to the labels, contained sodium benzoate, 15 spoiled. The bottles of unspoiled ketchup after remaining in the laboratory for about a month were placed in the incubator at 95Â° F. for three weeks, and were then taken out, and have been left in the laboratory since. The metal cap had been taken off frequently for observation, and the ketchup exposed, but the treatment did not cause them to spoil. The average number of days after which spoilage occurred for the 46 bottles without preservative was about fifteen, the minimum number being four days, the maximum number ninety-four days. The average number of days preceding spoilage in the case of 15 bottles with preservative was twenty-four days, the minimum number being three and the maximum sixty days. The majority of these had 0.1 per cent of sodium benzoate present; the others had a smaller amount, according to the manufacturerâs label. These data are not at all conclusive and further work on material of known history will be necessary. STERILITY OF KETCHUP. To determine the sterility of ketchup, cultures were made from 77 of the bottles. The method used was to wipe the bottles and cork stoppers with a damp towel and then remove the cork. The cork puller which was used grasps the neck of the bottle in such a way as to cover the opening and remove the cork without the inrush of air that occurs when the ordinary corkscrew is used. A flame was then passed over the mouth of the bottle, after which the upper layer of ketchup was poured out, so as to discard any material which might have been contaminated in handling. Tomato gelatin was used as a medium and cultures were made in petri dishes. There were 17 plates on which no organisms developed, indicating that the ketchup was sterile. Of the 60 plates having organisms, 54 had molds, 22 of these having molds alone; 21 plates had yeast-like organisms, 3 plates having these only; 29 plates had bacteria, 4 having bacteria alone. Sometimes a plate would have only one form of organism, but more often there was a mixture present. Of 15 plates having only one form of organism, 3 had yeast alone, 2 bacteria alone, and 10 had mold alone. Of the 77 bottles of ketchup from which the inoculations were made, 41 were without and 36 with preservative, and of the 17 sterile ketchups, 8 contained sodium benzoate and 9 were without preservative. A considerable part of the experimental ketchup proved not to be sterile. The organisms present were of the class which require oxygen for their growth and therefore they had only been arrested in their activity. No growth could take place so long as the air was excluded and therefore no spoilage could occur. When the cork was drawn, the organisms could grow and cause spoilage, and this is a much more potent factor than the entrance of germs from without. Bottling and sealing the ketchup quickly while hot so completely excludes the air that only a few colonies of yeast or mold may be found on subsequent microscopical examination. Filling at a low temperature and corking while cool allows sufficient air to remain incorporated in the ketchup and neck of the bottle to permit a considerable growth of the organisms and a product derived from good stock may thus acquire the appearance of ketchup derived from partially decayed material. A ketchup in which bubbles of air are incorporated in filling may show a growth of mold at each bubble throughout the mass. The foregoing statements apply to ketchup containing sodium benzoate as well as to the non-preservative goods of the character used in these experiments. EXPERIMENTS WITH PRESERVATIVES. SODIUM BENZOATE. The preservative in general use in ketchup is sodium benzoate. Salicylic acid is used, but only to a limited extent. The amount of sodium benzoate used, according to the labels, varies from one-sixteenth to one-tenth of 1 per cent; but on some labels the amount is not stated. Experiments were made to determine the amount necessary to check the spoilage of ketchup. Two organisms, a mold and a yeast, were selected on which to make the tests. The mold was the ordinary blue mold, Penicillium, which was present in many of the brands of ketchup and is found commonly on acid foods. It was selected on account of its prevalence and resistive power. The yeast was obtained from ketchup and was also a vigorous grower, forming a thick, wrinkled film on various media. Any effect on the growth of the yeast could be seen readily in its manner of forming the film. Portions of tomato gelatin to which 0.1, 0.5, 1, and 2 per cent, respectively, of sodium benzoate were added, were first inoculated with the mold. There was no development in those containing 1 and 2 per cent; a retarded development resulted in that containing 0.5 per cent, and the growth when 0.1 per cent was used was nearly normal, showing very little difference from that in the gelatin without sodium benzoate. Ketchup was next tried as a medium, but the amount of benzoate was reduced to one-sixteenth, one-twelfth, and one-tenth of 1 per cent, as it was thought that some of the other constituents of the ketchup were antiseptic to a slight degree. The growth in the ketchup was irregular, though the benzoate checked development in all. Equal amounts of benzoate were used in tomato bouillon, with practically the same results as in the ketchup. The development was checked in all, and in some plates one-sixteenth of 1 per cent seemed to be fully as efficacious as one-tenth of 1 per cent. When the mold was examined under the microscope, the filaments were found to be much swollen and distorted in shape, and filled with a coarsely granular protoplasm, containing much fat, as indicated by the blackening with osmic acid. The culture containing the mold which gave the least development seemed to show the least distortion and swelling of the filaments. The results indicated that in using sodium benzoate as a preservative there is uncertainty as to results, even when using the maximum amount allowed--one-tenth of 1 per cent. They also indicated that this preservative had an injurious effect on the living matter of the mold. (See Pl. II; compare with normal growth, Pl. I.) SALT. The effect of salt in checking development was tested by using tomato bouillon as a medium and adding 5, 10, 15, 20, 25, and 30 grams of salt, respectively, to 100 cc. These were inoculated with the mold. The 5-gram solution seemed to have no effect on development. When 10 grams were used growth appeared as soon as in the bouillon without salt, but was not so extensive. In the 15-gram solution growth was retarded four days, and most of that which did develop remained submerged, the mold growing normally on the surface. With 20 grams the growth was five days slower than the normal in starting, and after that there was only a slight development. In the 25-gram solution, the growth started at the same time as when 20 grams were employed, but remained stationary, while with the 30-gram solution, no development occurred. The yeast was checked slightly by 5 grams, and very materially by the 10-gram solution, as it required two days for a thin, delicate film to form, whereas in ordinary solutions a rather thick film is formed within twenty-four hours or even in less time. There was no development in the 15-gram solution. SUGAR. The effect of sugar was tested on both the mold and the yeast by adding it to tomato bouillon. It was supposed that a low percentage of sugar like the salt would plasmolyze the cells, and in this way check growth, but it seemed to have no effect until the amount was increased to 25 grams per 100 cc of bouillon. In this solution growth appeared as soon as with the weaker solutions, but there was a smaller amount. In the 25 to 40 gram solutions there was less development as the amount of sugar increased. In the 70 and 75 gram solutions growth was delayed one day in its appearance. In the 80, 85, and 90 gram solutions growth was delayed two days, the colonies growing submerged at first, but after a time forming on the surface. The mycelium remained very thin, but a thick layer of spores formed. From this point on the amounts were increased by 10 grams up to 200. The development became slower and less successively until 170 grams were added. In this case a small colony appeared on the surface in seven days, but seemed to grow less after that. The solutions were held, and in time crystals separated from the thick sirups. After two months dry-looking colonies developed along the edges, forming a ring, and some formed on the surface, these occurring also in the flasks containing 170, 180, 190, and 200 grams of sugar per 100 cc. The colonies were a dull greenish drab in spots, the remainder being white. For the yeast the 80-gram solution of sugar was the strongest in which any development took place. SPICES. Experiments to determine the value of the spices as antiseptics were made, using water infusions, acetic-acid extracts, and oil extracts. WATER INFUSIONS. In making the water infusions 20 grams of the whole spices, with 200 cc of water, were boiled for forty-five minutes. This is approximately the length of time that the spices are cooked in the ketchup in the factory. The liquid was then filtered and from 0.1 to 5 cc of the filtrate was used in 10 cc of tomato bouillon. The same organisms were used as in the former experiments. The tests showed that cinnamon and cloves were the strongest antiseptically. These checked growth when used in small amounts, but it required 3 cc of the cinnamon and 1 cc of the cloves to inhibit the growth of the mold. Mustard, paprika, and cayenne pepper checked growth also, but 5 cc, the highest strength used, did not inhibit growth. The ginger, mace, and black pepper had no apparent effect in the quantities used. The effect of the spices on the development of the yeast was somewhat different from their effect on Penicillium. The cinnamon showed the strongest action, 3 cc being effective, whereas 5 cc of the cloves was required. The cayenne pepper came next in effectiveness, and after that the black pepper. The ginger, mace, and mustard solutions had no effect in the strengths used. The remainder of the spice infusions were kept in glass-stoppered bottles in the laboratory, and in a few weeksâ time there was a coating of mold formed over the surface of the mace, the mustard, and the black and cayenne peppers. The paprika had small, stunted colonies dotting the surface. At the time that these experiments were made a quantity of the ground spices were placed in large petri dishes and water was added to make a heavy paste. One set of these was inoculated with the mold, and another set with the yeast, and all were kept in a warm place. No development of either organism appeared on the cinnamon, cloves, or mustard; on the others a growth first showed in three days. On a normal medium growth appears in twenty-four hours. On the mace, paprika, and cayenne pepper the Penicillium and yeast with which the pastes were inoculated were overgrown in a few days with black mold (_Rhizopus nigricans_). ACETIC-ACID EXTRACTS. In the manufacture of ketchup acetic-acid extracts of the spices are sometimes used instead of the whole spices, on account of their supposed antiseptic properties as well as their greater strength and convenience in handling. One minim of the standard acetic-acid extracts is equal in strength to 1 grain of the whole spices. The acid extracts obtained included allspice, celery, cloves, coriander, garlic, and black pepper. In the tests 0.1, 0.2, 0.3, 0.4, 0.5, and 1 cc, respectively, of the extract was added to 10 cc of tomato bouillon. One set was inoculated with the mold and another set with the yeast. In the case of the mold, no growth occurred with the allspice and cloves; the celery checked the growth materially, there being no indication of mold until the sixth day. Normally a fairly strong growth occurs in twenty-four hours. In the solution containing 0.3 cc there was only one small colony in thirteen days, and no further development. In the solution containing the coriander, the growth in the 0.5 cc solution did not appear for three days, the 1 cc solution showing no growth. The garlic had practically the same effect as the coriander, while the black pepper was stronger, no growth appearing in the solution containing 0.5 cc. The yeast was slightly stronger in resisting the effect of the extracts. No growth appeared with the allspice and cloves; 0.5 cc of the celery and 1 cc of the coriander were required to inhibit growth, and the garlic and black pepper gave similar results, a weak development occurring in the solutions containing 1 cc. OIL EXTRACTS. Oil extracts of the spices were tested in the same manner as the water infusions and the acetic-acid extracts. The oils were so strong that
{'title': 'Experiments on the Spoilage of Tomato Ketchup by A. W. Bitting', 'source': 'Project Gutenberg', 'lang': 'en'}