30B-28 |
Effectiveness of ozone and/or chlorine treatments on extending shelf life of fresh-cut lettuce salads |
A. GARCIA1, J. R. Mount1, P. M. Davidson1, and R. E. Yoder2. (1) Food Science and Technology, University of Tennessee, 2605 River Drive, Knoxville, TN 37996, (2) Agricultural and Biosystems Engineering, University of Tennessee, 2605 River Rd, Knoxville, TN 37996 Chlorine is an effective sanitizer against many foodborne microorganisms. However, it may cause the formation of carcinogenic trihalomethane compounds. Ozone is an effective disinfectant having greater oxidation potential than chlorine. Limited studies have been done to determine the optimum concentration and contact time for ozone and if there is a synergistic interaction with chlorine when treating minimally processed produce. Our objective was to determine the sanitizing efficacy of ozone and chlorine, alone or in combination on microbial reduction on fresh-cut salads. Iceberg lettuce was cut into 2 by 5cm strips and inoculated with 107CFU of a mixture of natural microflora strains isolated from cut lettuce stored at 10oC. 100g samples were treated with 1L distilled water solutions containing combinations of 0, 100, 150 or 200ppm chlorine and 0, 2.5, 5.0 or 7.5ppm ozone for a total of 16 treatments. Lettuce-water solutions were stirred constantly for 10 min and then lettuce was sampled for Aerobic Plate Count(APC). Commercially processed salads treated with chlorine, ozone or an ozone-chlorine mixture were evaluated for shelf-life using visual inspection by an untrained sensory panel (n=30). Lettuce treated with only chlorine had reductions in APC of 1.7 logs. Samples treated with ozone decreased in APC 1.1 logs. Lettuce treated with the combinations of chlorine and ozone had the greatest reduction in APC of 2.4 logs. Sensory evaluation showed that the commercially processed samples treated with chlorine were least desirable having the shortest shelf-life with product decay after 16 days of treatment. Samples treated with ozone alone had a shelf-life of 18 days. Lettuce treated with the combination had the longest shelf-life retaining good visual sensory characteristics until at least 23 days after treatment. Results suggest that washing fresh-cut salads with an ozone-chlorine sanitation treatment can improve and extend the shelf-life of these kind of products.
Session 30B, Fruit & Vegetable Products: Sensory, Product Development, Fresh-Cut, and Storage
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