Study On The Enrichment Technology Of ?-Aminobutyric Acid In Black Barley

?-Aminobutyric acid?GABA?is a functional component in cereals and animal brains,which has many biological activities including relieving anxiety,regulating blood lipid metabolism and lowering blood pressure.In natural grains GABA content is generally low.Black barley is a cereal grow at the alpine region,and has exploitation value since it rich in trace elements,dietary fiber and polyphenols.In this study,GABA in black barley was enriched by plant metabolism?germination?and microbial fermentation,which provided the basis for further development of functional cereal food using black barley as the main raw material.Firstly the germination conditions of GABA enrichment in black barley was explored.Soaking time,germination temperature and time were taken as the main factors,and three-factor and three-level orthogonal experiment was designed to set up the optimal germination conditions of black barley for GABA enrichment.The effects of hydrogen-rich water on the black barley germination and the its nutritional components including amino acids,protein,fat,starch,dietary fiber,mineral elements,vitamin B₁ and vitamin B₂ were further studied.UPLC-MS was used to analyze the effects of hydrogen-rich water treatment in the bioactive components,and the changes of phenolic acid content were detected using HPLC.Secondly,the process conditions of GABA enrichment in black barley using fermentation was explored.Fermentation strains,inoculation time and inoculum size were taken as the main factors,and three-factor and three-level orthogonal experiments were designed to set up the optimal fermentation conditions for GABA enrichment.The effects of fermentation on essential nutrients including protein,fat,dietary fiber,mineral elements,vitamin B₁ and vitamin B₂ in black barley were also explored.The results were as follows:?1?The optimal germination conditions for black barley were:soaking for 8 h,germination temperature 15 at?,germination time for 6 d.The content of GABA was 96.34 mg/100 g at this germination condition,which was 9.01 times higher than non-germinated black barley.Hydrogen-rich water treatment could significantly improve the germination potential,germination rate and growth rate of black barley at lower temperature?10??which were increased by 77.78%,18.82%and 83.33%respectively compared with the pure water group.?2?Germination could significantly led to the increasing of the content of protein,vitamin B₁,vitamin B₂,insoluble dietary fiber,free amino acids,some phenolic acids and some mineral elements in black barley.Specifically,essential,semi-essential and non-essential amino acids were significantly increased by 22.95,12.21 and 4.54 times,respectively,and the ratio of essential amino acids and non-essential amino acids were increased significantly by 5.05 times;umami,sweet,branched chain,and aromatic amino acid were also significantly increased by 1.98,7.27,30.39 and 15.32times,respectively.As for the free phenolic acids,the content of coumarinic acid,erucic acid and vanillic acid were significantly increased by 1.15,2.72and 3.53 times respectively,while in the bound phenolic acids,the contents of vanillic acid,syringic acid,ferulic acid and erucic acid were significantly increased by 1.44,2.57,2.28 and 3.07 times,respectively.For the mineral elements,calcium,iron and manganese were significantly increased by 1.28,1.39 and 1.53 times,respectively.Hydrogen-rich water treatment could significantly increase the above three free phenolic acids and the bounding sinapinic acids compared with the pure water group,which were increased by 343.20%,339.50%,162.70%and 124.30%,respectively,and the content of calcium and iron were increased 73.02%and 24.39%respectively compared with pure water group.?3?The optimum fermentation conditions for black barley were:strain No.10,fermentation time for 24 h,5%inoculation size.Under these conditions,the content of GABA was 43.56 mg/100 g,which was 2.34 times higher than unfermented black barley.The addition of 0.5%MSG could further increased the GABA content to 54.04 mg/100 g.Under optimal fermentation conditions,the content of vitamin B₁,vitamin B₂ and free amino acids in black barley were significantly increased by 194.75%,185.00%and 124.70%times respectively.For the mineral elements,calcium,iron and manganese were significantly increased by 103.28%,107.38%and17.80%times,respectively.Conclusion:GABA in black barley can be significantly enriched by plant metabolism?germination?and microbial fermentation.Under optimal germination conditions,GABA content was increased by 9.01 times,under optimal fermentation conditions,GABA content was increased by 2.34times.