91-7 |
Evaluations of disinfectants for control of pathogens in alfalfa seeds & sprouts |
L. R. BEUCHAT, P. J. Taormina, and W. R. Weissinger. Dept. of Food Science & Technology, Univ. of Georgia, Center for Food Safety & Quality Enhancement, 1109 Experiment St., Griffin, GA 30223 Outbreaks of infections associated with raw fruits and vegetables have occurred with increased frequency during the past decade. At least fourteen outbreaks of Salmonella and Escherichia coli O157:H7 infections linked to the consumption of alfalfa sprouts, clover sprouts, and mungbean sprouts have been documented since 1995. The level of safety risk associated with sprouts that are not cooked before eating has raised interest in evaluating a wide range of chemicals for their efficacy in killing pathogens on seeds intended for sprout production and on mature sprouts. Test chemicals have included chlorine (hydochlorous acid), chlorine dioxide, acidified sodium chlorite, various organic acids, trisodium phosphate, calcium hydroxide, hydrogen peroxide, ethanol, volatile plant compounds, and several commercial formulations. While treatment with some of these chemicals has been shown to reduce populations of Salmonella and E. coli O157:H7 by more than 6 log10 CFU/g, substantial loss of seed viability also often occurs. Treatment of alfalfa seeds with 20,000 ppm chlorine (as calcium hypochlorite), 1% calcium hydroxide, 500 ppm acidified sodium chlorite, and a prototype produce wash (Fit7) are most effective in reducing pathogens without sacrificing germination percentage. The delicate nature of alfalfa sprouts renders them extremely sensitive to chemical treatment. Gaseous acetic acid (500 ppm) and allyl isothiocyanate (200 ppm) reduce the number of Salmonella on alfalfa sprouts by about 7 log10 CFU/g but also adversely affect color, turgor, and overall appearance. Among the aqueous chemical treatments applied to alfalfa sprouts, acidified sodium chlorite shows the most promise. Disinfection of seeds before sprout production remains a unique challenge in terms of developing interventions for eliminating pathogenic bacteria without reducing yield or compromising sensory quality of mature sprouts. Combinations of chemical and physical treatments are currently being investigated on the assumption that multiple assaults will enhance lethality to pathogens that apparently are occasionally present in low numbers on alfalfa seeds.
Session 91, Acidified sodium chlorite - an antimicrobial intervention for the food industry
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