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Evaluation of pulsed light for inactivation of foodborne pathogens on fresh-cut lettuce: Effects on quality attributes during storage

Tao, Tingting, Ding, Chao, Han, Nengneng, Cui, Yu, Liu, Xianjin, Zhang, Cunzheng
Food packaging and shelf life 2019 v.21 pp. 100358
Escherichia coli, Listeria monocytogenes, Salmonella Enteritidis, Staphylococcus aureus, ascorbic acid, bacteria, chlorophyll, cold storage, color, decontamination, food packaging, food pathogens, fresh-cut produce, hydroponics, leaves, lettuce, molds (fungi), shelf life, storage temperature, storage time, total soluble solids, virulent strains, weight loss, yeasts
Minimally processed vegetables have a short shelf life and are susceptible to contamination of various foodborne pathogens. The aim of this work is to evaluate the bactericidal efficacy of pulsed light (PL) against four common foodborne pathogens inoculated on lettuce surface and its impact on quality attributes of lettuce through 8 days of storage at 4 °C. The results indicated that PL treatments were effective for inactivating the pathogens load on the leaves by 2.03–6.56 log10 CFU/g depending on the applied fluence. However, the susceptibility of tested pathogenic strains to PL treatments differed significantly (P < 0.05). Staphylococcus aureus was identified as the most sensitive strain to PL, Escherichia coli and Salmonella enteritidis showed moderated susceptibility while Listeria monocytogenes was most resistant. At the end of refrigerated storage, all PL treated lettuce maintained significantly lower total bacteria counts and total yeast & mold counts than the untreated control, which were within the maximum limit of 7.0 log10 CFU/g. PL treatments could maintained the product quality during 8 days of storage by minimizing weight loss, preserving color and keeping good level of total soluble solids, chlorophyll and ascorbic acid. To consider both safety and quality of fresh-cut lettuce as well as treatment feasibility, PL treatment with fluence of 8.2–12.5 J/cm2 was recommended for surface decontamination and shelf life extension of fresh-cut hydroponic lettuce.