摘要
对生鲜南瓜(Cucurbita moschata)所含谷氨酸脱羧酶(Glutamate decarboxylase,GAD)的最适反应温度、最适p H、热稳定性和冷冻稳定性等酶学特性进行研究,并利用其富集γ-氨基丁酸(γ-Aminobutyric acid,GABA),探索了反应时间、南瓜品种、缓冲体系、南瓜及味精添加量、料水比对富集效果的影响。结果表明,南瓜GAD最适反应温度为30~35℃,最适p H为5.8。南瓜GAD对热比较敏感,50℃保温30 min,酶活力损失20%,70℃以上保温30 min可导致酶活力完全丧失。冷冻对GAD影响较小,但长期冷冻仍会导致酶活力损失,冷冻8周酶活力损失36%。GABA最适富集条件为:以p H5.8,0.2 mol/L磷酸氢二钠-柠檬酸缓冲液作为反应溶液,南瓜与缓冲液比例为1∶3,南瓜添加量25%,味精添加量1.5%,30℃反应18 h,反应液中GABA浓度可达7633.2 mg/L,转化率为93.3%,单位质量南瓜GABA富集量为30.5 mg/g,与未富集时相比提高了132倍。
Several enzymatic characteristics of pumpkin glutamate decarboxylase（ GAD） including optimal reaction temperature,optimal reaction p H,heat stability,freezing stability were investigated.γ-Aminobutyric acid（ GABA） accumulation was carried out utilizing glutamate decarboxylase in fresh pumpkin（ Cucurbita moschata） and the effects of conditions（ reaction time,variety of pumpkin,buffer system,pumpkin and MSG concentrations,the ratio of material to water） on GABA accumulation were investigated.The results showed that,the optimal temperature and p H of pumpkin GAD were 30~35 ℃ and p H5.8 respectively.Pumpkin GAD was sensitive to heat,after incubation for 30 minutes at 50 ℃,20% loss of GAD activity,while incubation for 30 minutes at a temperature higher than 70 ℃,totally inactivation of GAD activity occurred. Freezing had little effect on GAD activity,while long-term freezing could still cause a loss of GAD activity,for example,36% GAD activity lost after eight weeks freezing.GABA concentration and conversion rate were 7633.2 mg/L and 93.3% respectively under the optimum conditions of pumpkin： disodium hydrogen phosphate-citric acid buffer（ p H5.8,0.2 mol/L） ratio 1 ∶ 3,pumpkin concentration 25%（ w/w）,MSG concentration 1.5%（ w/w）,temperature 30 ℃ and reaction time 18 h. Besides,under the optimum conditions,GABA yield reached 30.5 mg/g,132 times higher than before.
作者
舒成亮
王春茹
郭晓风
单胜艳
薛玉清
欧凯
李言郡
SHU Cheng-liang;WANG Chun-ru;GUO Xiao-feng;SHAN Sheng-yan;XUE Yu-qing;OU Kai;LI Yan-jun(Hangzhou Wahaha Group Co.,Ltd.,Key Laboratory of Food And Biological Engineering of Zhejiang Province,Hangzhou 310018,China)
出处
《食品工业科技》
CAS
CSCD
北大核心
2018年第16期191-194,219,共5页
Science and Technology of Food Industry
关键词
南瓜
谷氨酸脱羧酶
酶学特性
Γ-氨基丁酸
富集
pumpkin
glutamate decarboxylase
enzymatic characteristics
γ- aminobutyric acid
accumulation
