Distribution of Indicator Organisms and Incidence of Pathogenic Bacteria on Soybean Sprouts in Cook-chill System

Microbiological contamination in soybean sprouts was measured during the cook-chill procedure to evaluate the incidence of some pathogenic bacteria and indicator organisms, which can cause spoilage or may be related to food safety. Eight strains of psychrophilic, mesophilic, anaerobic, and spore-forming bacteria, coliforms, yeasts and molds, fecal Streptococcus, and Pseudomonas spp. were selected to evaluate the degree and progress of food contamination. Raw soybean sprouts harbored large populations of microorganisms at about $10^6-10^8$ cfu/g. Psychrophilic bacteria were found to be more abundant $(7.9\times 10^7\;cfu/g)$ than other microorganisms, and the numbers of mesophilic bacteria, anaerobic bacteria, and Pseudomonas spp. were very high $(> 10^7 cfu/g)$. Washing did not affect the bacterial count in raw soybean sprouts. Microbial count,> decreased to about $10^2-10^4$ cfu/g after blanching, and to undetectable levels immediately after cook-chilling. During the storage periods of 0, 2, 5, and 10 days at 3 or $10^{\circ}C$, three strains of psychrophilic, mesophilic, and anaerobic bacteria were reactivated. After 10 days, the microbial count,> of samples stored at 3 and 10 increased to approximately 5.0-20 and $10^5-10^7$ cfu/g, respectively. Strains such as Coliforms, yeasts and molds, fecal Streptococcus, and Pseudomonas spp. were not reactivated after] 0 days at 3 or $10^{\circ}C$. Aeromonas hydrophila, Pseudomonns aeruginosa, and Bacillus cereus isolated from raw and washed soybean sprouts were totally eliminated by blanching.