Isolation, identification and thermal inactivation of dominant spoilage bacteria in egg curds.

The egg curd is one of the most promising ready-to-eat egg products in China, which can greatly enhance the commercial value of eggs. At present, there are few studies on the spoilage bacteria of egg curds and the suitable heat treatment condition remains obscure. This study isolated and identified the spoilage bacteria from egg curds and then determined a suitable heat treatment condition. Bacillus velezensis EC 1 and Bacillus cereus EC 2 were isolated from spoiled products. The B. velezensis EC 1 spore was more thermal resistant than B. velezensis EC 1. The D 90 , D 95 and D 100 values of B. cereus EC 2 spores were 7.97, 2.23 and 0.93 min respectively, while the values of B. velezensis EC 1 spores were 26.87, 6.80 and 2.18 min, respectively. Based on the above D-values, we designed several heat treatment intensities and evaluated the heat treatment effect through shelf-life experiment. The egg curds heated at 100 °C for 10 min could maintain microbial safety during the 180-day storage period and the pH, total volatile basic nitrogen and thiobarbituric acid reactive substances values were relatively more stable. Therefore, in this study, the most suitable heat treatment condition for egg curds is 100 °C, 10 min. These findings will provide realistic guidance for egg curd manufacturers. • The spoilage microbes in heat treated egg curds were identified as B. velezensis and B. cereus. • The putrefaction ability of B. cereus EC 2 was stronger than that of B. velezensis EC 1. • The B. velezensis EC 1 spore was more thermal resistant than B. velezensis EC 1 spore. • The egg curds heated at 100 °C for 10 min could maintain microbial safety and the chemical indexes were relatively stable. [ABSTRACT FROM AUTHOR]