30B-29 |
The effects of ECA water dipping treatment of fresh-cut vegetables on bacterial contamination and shelf-life |
B. L. STROUD, Department of Food Science, University of Arkansas, Fayetteville, AR 72701, H. Yang, Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701, and Y. Li, Department of Biological and Agricultural Engineering, Department of Food Science, University of Arkansas, POSC O-411, Fayetteville, AR 72701. Microbial contamination of fresh-cut vegetables, ready to eat food products, is a major concern of the food processing industry. Cost effective technologies are needed to control the pathogens in vegetables. The objectives of this study were to determine if washing fresh-cut vegetables with Electrochemically Activated Water at different temperatures and chlorine concentrations could effectively reduce bacterial counts and to determine its effect on shelf life. 25 gram samples of three fresh-cut vegetables, broccoli, lettuce, and sprouts were treated at 100 and 300 ppm of chlorine and cross-tested at 25, 30, and 35 °C for 3 and 5 min. Vegetables were inoculated with one of the selected bacteria including Salmonella typhimurium, E. coli 0157:H7 and Listeria monocytogenes, at approximately 1x106 CFU/g, by suspending them in 150 ml of inoculated 0.85% physical saline solution for one hour and then rinsing them for 30 sec in double deionized water. Treatment was established by emersing the inoculated vegetable into 800 ml of ECA treatment water for the prescribed time and temperature. The vegetables were then washed, and stomached for 60 sec with 250 ml of buffered peptone water. Samples of stomaching water were plated using a WASP Spiral Plater and incubated at 37 °C for 48 h and bacterial colonies were counted with the ProtoCol plate counting system. Results showed that the treatment at 30 °C achieved best results for both bacterial reduction and the appearance of the vegetable. The treatment at 30 °C and 100 ppm chlorine could achieve 3.75, 3.61, and 2.37 log reduction for L. monocytogenes, E.coli 0157:H7, and S. typhimurium, respectively. At 300 ppm chlorine and 30 °C the treatment reduced E.coli 0157:H7, L. monocytogenes, and S. typhimurium by 3.37, 3.97, and 3.07 log, respectively. The ECA water has the potential for application to vegetable processing for continuous on-line treatment.
Session 30B, Fruit & Vegetable Products: Sensory, Product Development, Fresh-Cut, and Storage
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