Differential microbiota shift on whole romaine lettuce subjected to source or forward processing and on fresh-cut products during cold storage

• Published in: International journal of food microbiology 2024-05, Vol.416, p.110665-110665, Article 110665
• Main Authors: Gu, Ganyu, Ding, Qiao, Redding, Marina, Yang, Yishan, O’Brien, Regina, Gu, Tingting, Zhang, Boce, Zhou, Bin, Micallef, Shirley A., Luo, Yaguang, Fonseca, Jorge M., Nou, Xiangwu
• Format: Article
• Language: English
• Subjects: 16S rRNA gene amplicon sequencing; Aerobic bacteria; Arizona; California; cold storage; coliform bacteria; Escherichia coli O157; farms; food microbiology; Food safety; Fresh produce; genes; industry; Microbiome; Pre-processing delay; Produce quality; product quality; romaine lettuce; Total coliform
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2024.110665

Romaine lettuce in the U.S. is primarily grown in California or Arizona and either processed near the growing regions (source processing) or transported long distance for processing in facilities serving distant markets (forward processing). Recurring outbreaks of Escherichia coli O157:H7 implicating romaine lettuce in recent years, which sometimes exhibited patterns of case clustering in Northeast and Midwest, have raised industry concerns over the potential impact of forward processing on romaine lettuce food safety and quality. In this study, freshly harvested romaine lettuce from a commercial field destined for both forward and source processing channels was tracked from farm to processing facility in two separate trials. Whole-head romaine lettuce and packaged fresh-cut products were collected from both forward and source facilities for microbiological and product quality analyses. High-throughput amplicon sequencing targeting16S rRNA gene was performed to describe shifts in lettuce microbiota. Total aerobic bacteria and coliform counts on whole-head lettuce and on fresh-cut lettuce at different storage times were significantly (p