虾仁中副溶血弧菌灭活动力学模型的建立

Inactivation kinetics of Vibrio parahaemolyticus in peeled shrimp treated with organic acids

【目的】建立醋酸、乳酸和柠檬酸对副溶血弧菌(Vibrio parahaemolyticus)在生理盐水和虾仁中的灭活动力学模型,指导有机酸应用于虾仁加工过程中的抑菌保鲜。【方法】测定副溶血弧菌在生理盐水和新鲜虾仁中经不同浓度有机酸溶液浸泡处理10min后的存活率P,虾仁中的细菌存活率与有机酸浓度呈良好的线性关系;生理盐水中的存活率通过ln[P/(1-P)]转换成logit(P),与有机酸浓度之间的线性拟合度显著提高。通过拟合方程计算有机酸的50%和90%有效抑菌浓度(EC50和EC90),比较不同有机酸的抑菌能力以及在不同基质中的作用差异。【结果】副溶血弧菌在生理盐水中对有机酸较为敏感,在虾仁中的杀菌效果相对较差,虾仁中乳酸与柠檬酸的有效抑菌浓度(EC50或EC90)是生理盐水中浓度的160-200倍,醋酸的浓度比其在生理盐水中的浓度高出70倍以上,表明食品基质对有机酸的抑菌作用有显著影响,但采用的有机酸在虾仁中的EC90并未超过美国农业部规定的2.5%上限。以有机酸的总摩尔浓度比较,柠檬酸的抑菌能力最强,乳酸次之,醋酸最弱。【结论】抑菌剂效应呈非线性时,细菌存活率进行对数转换,可显著提高线性拟合度R2;食品基质对有机酸的抑菌作用有明显影响;应用浓度为2%的3种有机酸可以有效降低水产品中弧菌的污染量,提高产品的卫生质量。

[ Objective] To establish the kinetic inactivation models of Vibrio parahaemolytius in saline and peeled shrimp treated with acetic acid, lactic acid and citric acid for guidance of their potential application in shrimp decontamination. [ Methods] To determine the survival rate （P） of V. parahaemolyticus in saline and peeled shrimp treated with organic acids, dose-response in peeled shrimp between P and concentrations of organic acids was modeled directly. Logit （P） was transformed from survival P with the formula In [ P/（ 1 - P） ] for linear modeling. Both linear models were used to interpolate 50% and 90% effective inhibitory concentrations （ECs0 and EC90）, which were then used to compare the difference of inhibitory potency between saline and peeled shrimp. [ Results] Organic acids in saline were more inhibitory to V. parahaemolyticus in saline than in peeled shrimp, seen as 160 to 200-fold increase of EC50 and EC90for lactic acid and citric acid, and more than 70-fold increase for acetic acid. These results indicate that food matrix had significant impact on the antimicrobial activity of organic acids. We also found that EC90 of the tested organic acids in peeled shrimp was far below the 2.5% limit for use as food ingredients regulated by USDA. With equimolar concentration in the test solutions, the order of inhibitory potency is citric acid 〉 lactic acid 〉 acetic acid. [ Conclusion] Food matrix could have negative impact on antimicrobial activity of organic acids. Concentrations of organic acids around 2% could lead to significant reduction of V. parahaemolyticus contamination of peeled shrimp for improved food safety.