Kale shelf-life study

Pathogenic Campylobacter jejuni and E. coli O157:H7 were inoculated onto the surface of kale stored in a controlled environment at  4°C, ± 0.15°C,  and average humidity of 95%, ± 1.13°C, over a 23-day period. (days 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21), inoculated kale was destructively sampled and the surviving bacteria determined by serial dilution and plating onto Tryptic soy agar, Charcoal cefoperozone deoxycholate agar, and Eosin methylene blue for total aerobic bacteria, Campylobacter and E. coli O157:H7, respectively.Enrichment and PCR were used for detection when pathogens were not detected using serial dilution and plating. Aerobic heterotrophic bacteria increased over the 23-day period, in contrast, significant declines in the inoculated pathogens were observed. Inoculated E. coli O157:H7 survived longer on kale (up to 19 d), in comparison, Campylobacter was undetectable by day 13 using enrichment and PCR or plating.

将致病性空肠弯曲菌和O157:H7大肠杆菌接种于在4°C，±0.15°C的控温环境中储存的甘蓝表面，并在平均湿度为95%，±1.13°C的条件下，持续23天（第0天、第1天、第2天、第3天、第5天、第7天、第9天、第11天、第13天、第15天、第17天、第19天、第21天），对接种的甘蓝进行破坏性采样，并通过连续稀释和接种于胰蛋白胨大豆琼脂、活性炭头孢哌酮脱氧胆酸盐琼脂和酸性品红亚甲蓝琼脂来检测总需氧菌、弯曲菌和O157:H7大肠杆菌。当连续稀释和接种未能检测到病原体时，采用增菌和PCR方法进行检测。在23天的观察期内，需氧异养菌数量呈上升趋势，而接种的病原体数量则显著下降。与弯曲菌相比，接种的O157:H7大肠杆菌在甘蓝上存活时间更长（可达19天），至第13天，通过增菌和PCR或平板培养法已无法检测到弯曲菌。