盐度对虾油中蛋白酶系、微生物和及其品质的影响

本文以虾头虾壳发酵虾油,研究了盐度对发酵过程中蛋白酶组成、微生物、各质量指标以及风味的影响。研究表明:20%以上盐度才能较好地抑制虾油腐败;发酵过程中蛋白酶组成、细菌数量是动态变化的,虾头虾壳的内源蛋白酶在发酵过程中活力逐渐减小,而微生物蛋白酶种类增加,并表现出相当高的活力;发酵前期不耐盐细菌占优势,后期耐盐细菌逐渐增加,发酵过程中真菌几乎检测不到,以上说明细菌在虾油发酵过程中发挥重要作用。盐度越高对细菌的抑制作用越强,挥发性盐基氮(TVB-N)、三甲胺(TMA)等腐败产物的生成量降低;但高盐度也抑制蛋白酶活力,不利于氨基酸态氮(AAN)生成。总体上说,24%盐度的虾油,各种呈味氨基酸比例协调,酱香浓郁,氨味和腥臭味不突出,风味最佳。

Effects of Salinity on Proteases Composition, Bacterial Population and Quality of Shrimp Sauce During Fermentation

Shrimp processing wastes (heads, shells and tails) were fermented at differet salinity (16%, 20% and 24% ) to make shrimp sauce. The changes of protease composition, bacterial population and quality during fermentation were investigated. The results showed that the spoilage of shrimp sauce was effectively inhibited by using 20% or higher salinity. The protease composition and bacterial population varied during fermentation. The activities of most endogenous proteases gradually decreased. Meanwhile, some new microbial proteases appeared and showed relatively high activity. In the initial phase of fermentation, the non-halotolerant bacterial were dominant, while in the later phase the halotolerant bacteria increased. Thus, the bacteria played a significant role in fermentation. High salinity significantly inhibited the growth of bacteria and suppressed the production of the related putrefactive substance, such as total volatile basic nitrogen (TVB-N) and trimethylamine (TMA). It also decreased the protease activity and reduced the production of amino acid nitrogen (AAN). The shrimp sauce fermented at 24% salinity has a balanced ratio in terms of amino acids and flavor, and hence tastes better.