Changes in appearance and natural microflora on iceberg lettuce treated in warm,chlorinated water and then stored at refrigeration temperature |
| |
| Affiliation: | 1. Center for Food Safety, Department of Food Science and Technology, University of Georgia, Griffin, Georgia, 30223-1797;3. Center for Food Safety, Department of Food Science and Technology, University of Georgia, Athens, Georgia, 30602-7610;2. Center for Food Safety, Department of Food Science and Technology, University of Georgia, Office of Plant and Dairy Foods and Beverages, U. S. Food and Drug Administration, 200 C Street SW, Washington, D. C. 20204, USA;1. Department of Food Science & Technology, Ebonyi State University EBSU, Ebonyi State, P.M.B 053, Abakaliki, Nigeria;2. Department of Home Economics, Ebonyi State University EBSU, Ebonyi State, P.M.B 053, Abakaliki, Nigeria;3. College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, Jiangsu Province, PR China;1. State Key Laboratory of Environmental Criteria and Risk Assessment & State Environmental Protection Key Laboratory of Estuarine and Coastal Research, Chinese Research Academy of Environmental Sciences, Beijing 100012, China;2. Key laboratory of Mariculture & Stock Enhancement in North China''s Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 116023, China;1. School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, PR China;2. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, PR China;1. Departament de Química, Universitat de Lleida, Rovira Roure 191, 25198 Lleida, Catalonia, Spain;2. Dipartimento di Chimica, Università degli Studi di Pavia, via Torquato Taramelli 12, 27100 Pavia, Italy |
| |
| Abstract: | The objective of this study was to determine the effect of warm, chlorinated water on the survival and subsequent growth of naturally occurring microorganisms and visual quality of fresh-cut iceberg lettuce. After dipping cut lettuce leaves in water containing 20 mg l?1free chlorine for 90 s at 50°C, samples were stored at 5 or 15°C for up to 18 or 7 days, respectively. Populations of aerobic mesophiles, psychrotrophs, Enterobacteriaceae, lactic acid bacteria, and yeasts and molds were determined. The visual appearance and development of brown discoloration were monitored. Treatment of lettuce in warm (50°C) chlorinated water delayed browning of lettuce. Shelf life of lettuce stored at 5°C, as determined by subjective evaluation of color and general appearance, was about 5 days longer than that of lettuce stored at 15°C. Treatment in warm (50°) water, with or without 20 mg l?1chlorine, and in chlorinated water at 20°C significantly (α= 0·05) reduced the initial population of mesophilic aerobic microflora by 1·73–1·96 log10cfu g?1. Populations increased, regardless of treatment, as storage time at 5°C and 15°C increased. The same trends were observed in populations of psychrotrophs and Enterobacteriaceae. Yeast populations increased slightly in lettuce stored at 5°C but were consistently about 3 logs lower than mesophilic aerobes. Populations of molds and lactic acid bacteria were less than 2 log10cfu g?1throughout storage at 5 or 15°C. Results suggest that heat (50°C) treatment may have delayed browning and reduced initial populations of some groups of micro-organisms naturally occurring on iceberg lettuce, but enhanced microbial growth during subsequent storage. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
