Sensory and microbiological quality of shredded, packaged iceberg lettuce as affected by pre-washing procedures with chlorinated and ozonated water

Abstract

The effect of chlorinated, ozonated, and tap water in different washing procedures within the production process of shredded iceberg lettuce ( Lactuca sativa L.) on sensory and microbiological quality during storage in consumer-sized bags at 4 °C for 9 days was examined. Experiments were carried out under operating conditions of industrial practice using a commercial vegetable processing line. Processed and stored lettuce was evaluated by a sensory panel, and counts of aerobic mesophilic microorganisms, pseudomonades, and Enterobacteriaceae were determined. Parallely, instrumental colour and texture measurements were performed. To minimise cross-contamination between less contaminated inner leaves and highly contaminated outer layers during cutting and washing, the implementation of a pre-washing step of trimmed lettuce heads resulted in a ∼2 log 10 cycle reduction of the initial microbial load. While best sensory and microbiological quality was maintained in samples treated with chlorine, ozone and tap water treatment, respectively, were less effective in prolonging product shelf-life.