Studies On The Phytic Acid Changes And Baking Performance Of High-fibre Sourdough Bread

Wheat bran and barley bran were supplemented to produce high-fibre nutritional bread.The technology of sourdough was applied to improve the rheological properties, bakingproperties of high-fibre bread dough and reduce the phytic acid content of high-fibre breads.Enzymes were used to investigate the effects of the combination of enzymes and sourdoughon the staling characteristics of bread.Lactobacillus plantarum growth and acid production in wheat flour and bran bases weremonitored. The experimental results showed that Lactobacillus plantarum growed well bothin the flour and in bran bases. Lactobacillus plantarum growed rapidly with short lag phase inflour base and pH value was steady after10h fermentation. While in the base of bran, lagphase was longer and pH value kept steady after16h fermentation. Total titratable acidity(TTA) of bran base were higher than that in flour base during the fermentation especially inthe barley bran base. Fermented bran remarkably effected the pH and TTA values of breaddoughs. pH of bread dough decreased and TTA increased along with longer fermtation timeand more fermented bran sourdough.The effects of fermented bran on the rheological properties and rheofermentationproperties of bread dough were studied by dynamic rheometer and F3rheofermentometer. Therheological properties of bread dough were improved by adding proper amount of bransourdough with proper fermentation time. CO2production and gas retention capacityincreased. At the same fermentation time, G′and G″declined with the increasing addition ofbran sourdough, while Hm, Tx and R decreased to a certain extent. G′and G″of doughadding10%barley bran sourdough fermented for8h (10%-8h) or20%wheat bran sourdoughfermented8h or16h were higher than that were unfermented. Hm, Tx and R valuesincreased to maximum which were most close to the control by adding20%-8h barley bransourdough or20%-16h wheat bran sourdough.Specific volume, texture profiles, crumb cell structure parameters and sensoryevaluations of breads with bran sourdough were determined. The results indicated that properLactobacillus fermentation lessened the undesirable impacts on baking properties of doughcaused by adding bran. Baking properties of20%-8h barley bran sourdough bread and20%-16h wheat bran sourdough bread were significantly improved of which specific volumeincreased, hardness decreased, distribution and size of crumb cell structure were mostcompared to the control and sensory scores were the highest and most favored by customers.The content of phytic acid, an anti-nutritional factor, in fermented bran, bread dough andhigh-fibre bread were determined. Lactobacillus fermentation effectively reduced the phyticacid content in bran sourdough which continued to decrease with longer fermentation timeand accordingly reduced that in bread doughs and breads particularly in wheat bran sourdoughbread. The baking process of breads influenced the phytic acid content to a certain degree. Nomatter barley or wheat bran sourdough breads, content of phytic acid were significantlydecreased after baking.Water states of bread dough were analyzed by Thermo Gravimetric Analyzer (TGA). The addition of bran led to more water loss from dough system. The water loss of dough combinedwith bran sourdough and xylanase was the highest during heating. Peak area ratios ofhigh-temperature peak of samples contained bran were higher and the addition ofLactobacillus plantarum strengthened the binding power between water and components ofdough with higher high-temperature peak and moisture content. The combination of bransourdough and enzymes was beneficial to bind water in the gluten to some extent andincreased specific volume of breads further. The accretion of hardness and amylopectinretrogradation enthalpy of crumb decreased during storage and the water migration fromcrumb to crust slowed down. In conclusion, the baking properties were improved and breadstaling delayed.