不同漂烫、蒸制及冻存处理对菜用大豆贮藏和感官品质的影响

Effects of Blanching,Steaming and Freezing Treatments on The Storage and Sensory Qualities of Vegetable Soybeans

试验以菜用大豆为供试材料,首先研究不同漂烫和蒸制时间对过氧化物酶(Peroxidase,POD)活性和豆荚色泽的影响,并在此结果基础上研究不同冻存方式(–20、–80℃冷冻24 h后转–20℃和–80℃贮藏)对菜用大豆贮藏过程中品质、矿物质元素和感官品质的影响。结果表明,1.5-4min漂烫和蒸制菜用大豆后POD完全失活;漂烫和蒸制时间对豆荚表面亮度(L*值)无显著影响,但红绿值(a*值)随漂烫和蒸制时间延长先降低后增加,而黄蓝值(b*值)在漂烫和蒸制处理2 min后降低。为最大程度抑制POD活性并保持豆荚鲜绿色,漂烫和蒸制时间应控制在2 min。随后,将漂烫和蒸煮处理后的菜用大豆分别在–20、–80℃速冻24 h后再转存–20℃以及–80℃条件下贮藏4个月,结果发现–80℃冻存方式能延缓漂烫和蒸制处理后菜用大豆中淀粉、抗坏血酸和还原性糖下降。漂烫和蒸制处理均能造成Fe、Zn和Ca损失,提高Mg含量,但对K无影响。此外,–80℃冻存方式能保留漂烫处理中较高的Ca含量。贮藏2个月和4个月后,漂烫处理的菜用大豆香气、质地和口感均高于蒸制处理组,尤其是在–80℃冻存条件下。为最大程度上保持菜用大豆贮藏和感官品质,应选用漂烫2 min预处理菜用大豆并在–80℃下进行冷冻贮藏,但出于成本考虑,–80℃冷冻24 h后转–20℃的冻存方式更经济。

Vegetable soybeans was used as the material,the effects of dfferent blanching and steaming time on peroxidase(POD)activity and pod skin color were first investigated,and on the basis of the results,the effects of different freezing storage conditions(-20,-80℃for 24 h then stored at-20℃,and-8o C)on the storage quality,mineral elements,and sensory quality of vegetable soybeans were evaluated.The results showed that POD activity was completely inactivated after 1.5-4 min of blanching or steaming;the surface brightness(L*)of the pods was not affected by blanching and steaming time,but the red-green values(a*)tended to decrease and then enhanced with increasing blanching and steaming time,while the yellow-blue values(b*)decreased significantly after 2 min of blanching and steaming.In order to maximize the inhibition activity of POD and maintain the bright green color of the pods,the blanching and steaming time should be controlled at 2 min.Subsequently,the untreated,blanched,and steamed vegetable soybeans were frozen at-20,-80℃for 24 h and then stored at-20℃,and-80℃for up to 4 months.It was found that-80℃freezing storage could delay the declines on starch,ascorbic acid,and reduced sugar in both blanched and steamed vegetable soybeans.Although both blanching and steaming treatments resulted on losses in Fe,Zn,and Ca and an increase on Mg,no effect on K.Additionally,-80℃freezing storage maintained higher Ca in blanched vegetable soybeans compared to the steaming treatments.After 2 and 4 months of storage,the aroma,texture,and taste of blanched vegetable soybeans were better than those of the steamed ones,especially in-80℃freezing storage.In order to maximize the preservation and sensory quality,vegetable soybeans should be blanched for 2 min and stored at-80℃.However,for cost reasons,freezing at-80℃for 24 h followed by storage at-20℃is more suitable for industrial processing.