Combined effects of heat and acetic acid against foodborne pathogens for the preservation of asparagus
J. H. SHIN, S. Y. Lee, R. H. Dougherty, D. H. Kang
Book of Abstracts, 2004 IFT (Institute of Food Technologists) Annual Meeting and Food Expo, 13-16 July 2004, Las Vegas, Nevada, USA. 321 pages.
2004
บทคัดย่อ
Combined effects of heat and acetic acid against foodborne pathogens for the preservation of asparagusAs increased consumption of fresh vegetables raises the possibility of contracting foodborne illnesses through contaminated produce. However, demand for minimally processed vegetables is increasing. Proper treatment methods should be evaluated to ensure the safety of minimally processed vegetables. The objective of this study was to evaluate the combined treatment of heat and acetic acid to control foodbornepathogens in asparagus. Each of three strains of Escherichia colt 0157:H7, Salmonella Typhimurium, and Listeriamonocytogeneswas used to inoculate into asparagus paste. Samples were prepared to achieve various concentrations of acetic acid (0, 0.25. 0.5. 0.75, 1, 1.5. and 2% (v/v)) by adding the appropriate amount of vinegar, 50g ground asparagus, and 2% (w/v) salt. Prepared culture cocktails of foodborne pathogens were inoculated into asparagus samples at a level of 106-7 CFU/ml. Heat treatment of each sample was conducted in a water bath until internal temperatures reached to 40, 50, 60, and 75°C. Samples were stored at room temperature and enumerated at 0, 0.5, 1, 2, and 3 d. Combined treatment of heat and acetic acid showed synergistic effects against foodborne pathogens. More than 5 log10 reduction of S. Typhimuriumwas achieved with 1% acetic acid at 50°C, whereas 0.5% acetic acid required 75°C heat treatment. After 3 days of storage atroom temperature, the level of Salmonella was below the detection limit with 1%-40°Ctreatment. L monocytogenesshowed resistance to heat and acetic acid treatment. To obtain 5 log10 reduction at 1% acetic acid required 60°Cheat treatment. E. coli 0157:H7 treated with 1% acetic acid showed 5 log10reduction at 75°C. To achieve 5 log10reduction at 50°C, at least 2% acetic acid was needed. These findings suggest that the synergistic effect of heat and acetic acid possibly lowered the temperature and amount of acetic acid required for minimally processed vegetables.