Development Of Enriched γ-aminobutyric Acid Chickpea Sourdough And Its Application In Bread

In this study,Xinjiang Kabuli chickpea was used as the fermentation material for enriching gamma-aminobutyric acid(GABA),and the fermentation strains with high GABA yield were screened from six Lactic acid bacteria(LAB).The chickpea sourdough was used in bread making.The effects of its addition on the rheological properties of bread dough and the baking,nutrition,flavor and storage characteristics of chickpea bread were analyzed,which provided ideas for the development of new natural functional foods with healthy added value.The main research contents and conclusions are as follows:The fermentation strains with high production of GABA and other active ingredients were screened from the selected 6 strains.The six strains of Lactobacillus grew well in the chickpea substrate.Lactobacillus brevis CG had the longest logarithmic phase and the most stable growth during the fermentation process.The fermentation conditions for sourdough preparation were inoculation period of 6 h,fermentation temperature of 30°C and fermentation time of 24 h.EPS content reached 1396.29 mg/L.GABA content was 149.77 mg/100 g,49.43 times that of chickpea dough(CD,3.03 mg/100 g).The total free amino acid content of BCSD was 1645.73mg/100 g,which was significantly higher than that of CD(755.18 mg/100 g).The biochemical properties of the enriched GABA chickpea sourdough showed that the protein of the chickpea sourdough fermented by six LAB was hydrolyzed to a great extent,and the oligopeptides in BCSD was the highest.After fermentation,the total phenolic content was accumulated and the total flavonoid content was increased by 16.67%.LAB fermentation had positive effects on DPPH,ABTS free radical scavenging and FRAP iron atom reduction capacity of chickpeas,and BCSD showed high antioxidant capacity.The chickpea sourdough obtained under the optimal conditions was added to the bread dough system,and it was found that chickpea sourdough had positive effects on the physical properties and microstructure of the bread dough.At the same scanning frequency,although the G’ and G " of the chickpea added dough were decreased compared with wheat bread dough(WBD).G’ and G" in Lactobacillus brevis CG fermented chickpea bread sourdough(BCSBD)were 33.33% and 27.75% higher than those in chickpea bread dough(CBD),respectively.Compared with CBD,the LA/AA-BD and BCSBD groups showed a decrease in disordered curl and an increase in α-helix.It indicates that acidification can transform disordered structures into ordered structures.CLSM observed that the BCSBD gluten network was more regular and denser.In summary,it is shown that the sourdough affects the thrust rod of the bread dough structure.Compared with CBD,the BCSBD group occupied a larger area of bound water,indicating that the components in LAB fermented sourdough were more tightly bound to water molecules.Chickpea sourdough bread dough was baked into bread,and test results showed that the addition of chickpea sourdough improved the baking and nutritional properties of chickpea bread.Compared with chickpea bread(CB),the specific volume of Lactobacillus brevis CG fermented chickpea sourdough bread(BCSB)and Lactic/Acetic acidified bread(LA/AA-B)increased by 11.47% and 8.83%,respectively,which was close to that of wheat bread(WB).The pore structure of BCSB was compact and uniform,and the shape of BCSB was slender,which has better ductility.The holomorphic structure of BCSB was superior to CB and similar to WB.Amino acid content of BCSB increased significantly,and the GABA content increased from 12.13 mg/100 g to 45.90 mg/100 g in CB.Compared with WB,Lactobacillus brevis CG fermented chickpea sourdough bread showed the most significant improvement in IVPD,increasing by 17.38%.Lactobacillus brevis CG fermented chickpea increased the total phenolic and flavonoid content of bread and improved the overall antioxidant activity of bread.In addition to this,lactic acid bacteria fermentation can also improve the flavor of chickpea bread.After detection by electronic tongue,electronic nose and gas chromatography-mass spectrometry(GC-MS),it was found that the sour and salty taste of BCSB were significantly enhanced compared with CB,and the bitterness and astringency were significantly reduced.The BCSB group has the most abundant types and contents of volatile flavor compounds,mainly alcohols and ketones.After Lactobacillus brevis CG fermentation,the contribution of the characteristic aldehydes with green grass flavor and bean odor to the flavor of chickpea bread was significantly reduced,and the quality was improved.The storage characteristics showed that the addition of sourdough could greatly reduce the water loss in bread,slow down the recrystallization rate of starch and reduce the hardening rate of bread during storage.