微生物型鲜牛奶时间温度指示器

目的为了准确表征鲜牛奶的新鲜度,制备一种微生物型时间-温度指示器。方法选择瑞士乳杆菌菌种作为微生物基础,采用SPG膜乳化技术制备微生物微胶囊,按照微生物胶囊与固体基质的不同比例制作3种固体微生物时间-温度指示器,以色差值为变化参数研究其动力学特性,并与应用的鲜牛奶在恒温及变温条件下进行匹配试验。结果 3种不同比例时间-温度指示器的活化能与鲜牛奶的活化能差值在25 kJ/mol之内,其中当微胶囊质量与固体基质体积之比(g/mL)为1∶2时,在变温条件下两者的等效温度差值为2.1℃,TTI预测食品货架期终点的误差为3%。结论在恒温和变温等2种条件下时,制备的微生物型TTI可以精准实现鲜牛奶货架期的可视化。

Microbial Time-temperature Indicator Applied in Fresh Milk

The work aims to prepare a microbial time-temperature indicator, in order to characterize the freshness of fresh milk accurately. Microbial microcapsules were prepared by SPG membrane emulsification technology on the basis of Lactobacillus helveticus strains. Three kinds of solid microbial time-temperature indicators were made according to different proportions of microbial capsules and solid substrates. Their dynamic characteristics were studied by their color difference values. The test matching the applied fresh milk was carried out under the conditions of constant and variable temperatures. The difference of activation energy between three TTIs at different proportions and fresh milk was within 25 kJ/mol. When the ratio(g/mL) of microcapsule in mass to volume of solid matrix was 1∶2, the difference of equivalent temperature between the two indicators was 2.1 ℃ under variable temperature, and the error of TTI in predicting the end point of food shelf life was 3%. The microbial TTI prepared can accurately visualize the shelf life of fresh milk under constant and variable temperatures.