Abstract:To investigate the enrichment of γ-aminobutyric acid（GABA）and its regulatory mechanism in highland barley by low-temperature germination，this study investigated the effects of soaking time，germination time，and incubation temperature on GABA synthesis in highland barley using 'Chaiqing No.1' barley as the raw material.Based on single-factor experiments，the process conditions for enriching barley GABA by lowtemperature germination were optimized using response surface experiments.Meanwhile，the effects of lowtemperature germination on the activities of key regulatory enzymes for GABA（glutamate decarboxylase，polyamine oxidase，and diamine oxidase）were studied to reveal their regulatory mechanisms.The results showed that under the process conditions of soaking for 8 h，germination for 16 h，and incubation temperature of 0 ℃，the mass fraction of GABA in the germinated barley grains was（78.70±1.73）mg/100 g，which was 1.74 times that of the highland barley raw material.This indicated that low-temperature germination could efficiently enrich GABA in highland barley.Glutamate decarboxylase had a more significant impact on GABA synthesis，while polyamine oxidase activity was generally low，indicating that the GABA pathway was the main route for GABA synthesis in barley under low-temperature germination.