bread , especially wheat bread , is widely consumed all over the world particularly in the developing countries and is an important source of protein and calories . bread is not spoiled by the microorganism or endogenous enzymes ; however , its quality is lost by staling during storage . bread staling is a very complex process and many physicochemical changes occur that culminate in recrystallization of amylose and amylopectin . there have been many approaches on how to retard the process , among which the most successful ones are the use of additives such as emulsifiers and enzymes . there are several studies showing the potential use of hydrocolloids in baking industry as a way to retard staling [ 46 ] . taftoon is one of the popular iranian flat breads , produced from soft white wheat flours of higher extraction level . the bread has a round or oval shape , with the dimensions of 400500  mm length , 400500  mm width , and 2  mm thickness , with the average weight of 149 - 150  g. ingredients of taftoon bread are flour = 100  kg , water = 7890  l , yeast = 450650  g , and salt = 90130  g. the chemical compositions of a loaf of taftoon bread are crude protein = 10.47% dry mass , crude fat = 0.57% dries mass , crude fiber = 0.92% dry mass , ash = 2.53% crud mass , hydrocarbons = 85.5% dry mass , nacl = 0.86% dry mass , and moisture = 26.87% , with the ph value of 7 and 389  kcal/100 energy . salep gum is produced by grinding the dried tubers of certain wild orchids ; it is commonly used as a thickening and stabilizing agent ; especially in ice - cream and desserts . chemical structure of zedu has not yet been studied in detail and is just known to contain a compound named cerasin . the substance is insoluble in cold water , while it shows properties similar to arabic gum in boiling water . therefore , the aim of present study is to analyze the effects of salep and persian gums on rheological and qualitative characteristics and retarding staling of taftoon bread . to the best of our knowledge , commercial wheat flour ( 87% extraction levels ) containing 12.85% protein and 1.03% ash was obtained from a local market . hydrocolloids in powder form were bought from a local market ( salep gum : moisture = 10.83% , protein = 4.95% , ash = 1.91% , glucomannan = 51.2% , starch = 7.99% , and ph = 5.61 ; persian gum : moisture = 8.89% , protein = 0.209% , ash = 2.48% , uronic acid = 9.70% , galactose = 28.20% , and ph = 4.62 ) . some characteristics of the flour such as protein , moisture , ash , and wet gluten content , as well as zeleny sedimentation value and falling number , were determined according to the aacc standards . the effect of hydrocolloids on dough mixing properties was determined by brabender farinograph and extensograph ( brabender 1600 , sweden ) according to the aacc guidelines . basic bread formula ( traditional taftoon bread ) based on 1000  g flour consisted of compressed yeast 0.5% , salt 1% , and water up to consistency of 500 bu . then , according to previous studies and our initial experiments , persian gum was added to the flour at three concentration levels ( w / w ) of 0.5% , 1% , and 3% . salep gum was also added at four concentrations levels ( w / w ) of 0.5% , 1% , 3% , and 5% . moreover , a mixture of the two hydrocolloids at concentrations of 0.5% + 0.5% , 0.25% + 0.75% , and 0.75% + 0.25% were added to three samples . in this regard , the samples were as follows : con : control without any gums , p(0.5 ) : dough with 0.5% persian gum , p(1 ) : dough with 1% persian gum , p(3 ) : dough with 3% persian gum , s(0.5 ) : dough with 0.5% salep , s(1 ) : dough with 1% salep , s(3 ) : dough with 3% salep , s(5 ) : dough with 5% salep , s(0.5)p(0.5 ) : dough with 0.5% salep and 0.5% persian gum , s(0.75)p(0.25 ) : dough with 0.75% salep and 0.25% persian gum , and p(0.75)s(0.25 ) : dough with 0.75% persian gum and 0.25% salep . the ingredients were mixed and dough was fermented at 30c for one hour , divided into 300  g pieces and proofed at 30c for 15  min , and then sheeted and baked in a traditional oven at 200c . breads were cooled down at the room temperature and then packed into polyethylene packages . as bread staling is proportional to crumb firmness , crumb texture was assessed by a texture analyzer ( stable microsystems , surry , uk ) regulated for bread under the following conditions : load cell , 1500  n ; plunger speed , 120  mm / min ; five - blade kramer shear cell . breads were prepared in small pieces ( 52522  mm ) for this study . for this study , taftoon bread was prepared in small pieces ( 20202  mm ) and was placed in x - ray diffractometer after 0 , 24 , and 48  h storage at the room temperature . x - ray patterns of bread were taken with philips analytical diffractometer ( almelo , netherland ) ; type xpert mpd ; with the generator setting of 40  kv , 30  ma ; 2 was 250 with a scanning speed of 0.02/s and time per step of 1 ; step size [ 2 ] : 0.0200 ; and anode material of co (  = 1.78a ) . different sensory indexes such as shape , upper and lower surface characteristics , softness or hardness , and aroma were scored from 1 to 5 for poor to excellent , respectively . according to rajabzadeh , the following formula was used to calculate the overall score ( q ) . q = (p  g)/(g ) where p is the sensory score and g is the coefficient of each sensory index . g values for appearance , upper face properties , lower face properties , porosity , texture ( firmness and softness ) , chewability , and aroma and flavor were 1 , 2 , 1 , 2 , 3 , 2 , and 9 , respectively ( suggested by rajabzadeh ) . evaluation of iranian traditional breads is designed through the review and the comments received from the public . that based on scientific and qualitative criteria , empirical coefficients and according to the characteristics of each of the bread is done . all the chemical properties , dough rheology , and bread quality tests were performed in three replicates . the data were statistically analyzed by the analysis of variance in randomized complete blocks using the sas software with eleven samples ( including the control ) . the least significant difference ( lsd ) among samples was calculated at the significance level of 0.01 . the wheat flour characteristics are shown in table 1 . among the chemical characteristics , quantity and quality of protein breads of optimal quality are produced with flour from hard wheat 's with protein contents of 1012% . the effect of hydrocolloid addition on the farinograph measurements is summarized in table 2 . according to the table , water absorption by addition of salep and persian gums the highest absorption was observed when salep gum at the concentration of 5% was added and lowest adsorption was observed with addition of persian gum at the concentration of 3% . the effect observed with salep gum agrees with increased water absorption found by rosell et al . the effect is due to the presence of hydroxyl groups in the hydrocolloids structure [ 5 , 16 ] . the effect of persian gum on water absorption , however , disagrees with other studies on hydrocolloids . the water absorption of the flour depends on the swelling substances in the wheat ( proteins and pentosans ) and the mechanically damaged starch granules . it seems that the higher value of protein in salep gum could explain its greater water absorption ability . the reason so far is unknown ; it may be due to the presence of a substitute named  cerasin . this finding holds true in the persian gum , but there are no specific trend in salep . the highest degree of softening 10  min ( indicating fast gluten network formation ) after addition was observed for 0.75% persian plus 0.25% salep gums and the lowest was observed for 3% persian gum . the highest degree of softening 12  min ( indicating good workability of the dough ( strong dough ) ) after addition was observed for 0.5% and 1% persian gum , while the lowest was observed for 5% salep gum . 's   research , with increasing the softening degree , dough development time significantly reduced . each hydrocolloid affected the time required to reach dough development time ( consistency ) of 500  bu in a different manner . the longest development time was observed with salep gum at the concentration of 5% and the shortest time was observed for 0.75% salep gum plus 0.25% persian gum . persian gum at 3% concentration and salep gum at 5% concentration increased the stability significantly , and the control and other samples were not significantly different in this regard . findings of the present study showed no specific trend of stability in the salep and persian gums . various gums have different behaviors in relation to the duration of the show dough [ 5 , 18 ] . it seems that the different behaviors come from the differences in the structure and chemical compositions of the gums . the effects of adding hydrocolloids on the extensograph measurements after resting time of 45 , 90 , and 135 minutes are shown in tables 3 , 4 , and 5 , respectively . extensograph measures of dough extensibility and resistance to extension , and thus the viscoelastic behavior of the dough , can be determined . the energy or work input required for the deformation increased by addition of salep and persian gums . moreover , at each time measured ( after 45 , 90 , and 135  min ) , control sample showed the lowest energy . the control sample exhibited higher extensibility and dough containing hydrocolloids exhibited lower extensibility after 45 , 90 , and 135 minutes . it seems that by adding these two gums , the dough becomes too strong . by adding the hydrocolloids , resistance to extension and the ratio of resistance to extension or extensibility increased . salep gum and persian gum at concentrations of 5% and 3% , respectively , showed the highest and the control sample showed the lowest values of resistance to extension and resistance to extension ratio after the resting time of 45 , 90 , and 135 minutes . the results obtained in the current study showed that by adding these two gums , dough are stronger . this is in agreement with the findings of tavakolipour and kalbasi - ashtari   and guarda et al . . the highest farinograph quality value was obtained for addition of 3% persian gum and addition of 1% salep gums , while the lowest value was observed for addition of 0.5% persian gum and also addition of 0.75% persian gum and 0.25% salep gum . the farinograph quality values ( valorimeter value ) were obtained according to development time and stability . as it was shown , when the quality value was higher , the dough rheological properties were better . with regard to the farinograph and extensograph results , significant differences were observed between the control sample and the sample containing 5% salep plus 3% persian gums . shear force values of breads during 48  h of storage are summarized in table 6 . the results showed that when the staling of bread occurs , texture of bread becomes stiffer . the effect observed is in agreement with increased shear force found by tavakolipour and kalbasi - ashtari , when they added hydroxy propyl methylcellulose ( hpmc ) and carboxy methyl cellulose ( cmc ) to the dough . however , this is inconsistent with the results reported by rosell et al .   when they added xanthan to the dough . salep gum at 5% and persian gum at 3% concentrations significantly decreased and increased the shear force , respectively ( p < 0.01 ) . decreased shear force value in bread containing 5% salep gum is probably due to the high water absorption ability of this hydrocolloid . shear force value after 48  h for the bread containing 5% salep gum is lower than that for the control bread immediately after baking . so , salep gum acts as antistaling agent , while persian gum at any time increases the shear force value . it seems that the greater water absorption ability in salep gum could explain the antistaling act . this factor can delay the crystallization of starch [ 1 , 4 , 5 ] . effect of hydrocolloids on the sensory parameters is presented in table 7 . among different sensory parameters , firmness and softness  of the breads containing hydrocolloids showed significantly higher scores ( p < 0.01 ) . with regard to the firmness and softness parameters , the samples were not significantly different in overall score , including the scores of aroma and flavor , porosity , and lower face properties . figure 1 shows the x - ray diffraction diagrams of fresh and aged taftoon bread after the storage time of 0 , 24 , and 48  h in the control ( bread without any gums ) , bread with 3% persian gum , and bread with 5% salep gum , respectively . it is noticeable that peak intensities , that is , starch crystallinity , increased with time and the peak areas in bread samples were 3365.955 , 2201.876 , and 2039.580  cm ( in the control ) ; 2761.297 , 2101782 , and 1836.068  cm ( in the sample containing 3% persian gum ) ; 2728.964 , 1616.006 , and 1325.967  cm ( in the sample containing 5% salep gum ) after 0 , 24 , and 48  h , respectively . results showed that the decrease in the peak area in the bread sample containing 5% salep gum was higher ( 291  cm ) , when compared with the bread sample containing 3% persian gum ( 265  cm ) and the control sample ( 162  cm ) . furthermore , salep gum ( at 5% w / w flour basis ) acted as an antistaling agent due to the high water absorption ability of this hydrocolloid . this study shows that salep gum and persian gum increased and decreased water absorption of dough , respectively . the farinograph quality value obtained shows that persian gum decreased the water absorption , while improved some other baking properties of dough and so shows dual nature of persian gum . addition of salep gum at the concentration of 5% prolongs freshness of bread during storage at the room temperature . sensory assay revealed that hydrocolloid significantly increases the softness of bread , while no statistically significant changes occurred in the overall palatability .
effects of salep gum at concentrations of 0.5% , 1% , 3% , and 5% ( w / w flour basis ) and the persian gum at concentrations of 0.5% , 1% , and 3% ( w / w flour basis ) and combination of the two gums at concentrations of 0.5% + 0.5% , 0.75% + 0.25% , and 0.25% + 0.75% on rheological properties of the wheat flour dough and quality of taftoon bread were studied with regard to retardation of staling . 
 rheological ( farinograph and extensograph ) characteristics , staling , and organoleptic evaluations were performed on the dough and the resulting taftoon bread . 
 statistical results showed that the salep gum at 5% and persian gum at 3% ( w / w flour basis ) had a significant effect on the dough properties . 
 salep and persian gums when each separately added increased and decreased dough water absorption , respectively . 
 both hydrocolloids increased the dough resistance to extension and decreased its extensibility . 
 persian gum shows dual nature in water absorption and some other baking properties . 
 textural studies revealed that addition of 5% salep gum ( w / w flour basis ) reduced the bread crumb firmness and delayed the staling process of the taftoon bread . 
 x - ray diffraction study also confirmed this result .