15D-9 |
Inactivation of Salmonella Typhimurium in apple juice by combining nisin and cinnamon |
J. Yuste and D. Y. C. FUNG. Dept. of Animal Sciences & Industry, Kansas State Univ., Call Hall, Manhattan, KS 66506-1600 Salmonella Typhimurium can occur in foods that are raw, improperly heat-treated, and cross-contaminated after adequate heat treatment. Some outbreaks of Salmonella food poisoning have been traced to unpasteurized apple cider. We have observed the killing effect of cinnamon on Salmonella Typhimurium in apple juice. The lethal effect of nisin and cinnamon on Salmonella Typhimurium in apple juice was investigated. Nisin (25, 50, 100, and 200 ppm, w/v) and cinnamon (0 and 0.3%, w/v) were added to pasteurized apple juice (pH=3.6). Salmonella Typhimurium (Food Microbiology Culture Collection of KSU) was inoculated at 4 log CFU/mL. Samples were stored at 5 and 20ºC. Counts on tryptic soy agar (TSA), xylose lysine desoxycholate (XLD) agar, and thin agar layer (TAL; XLD agar overlaid with TSA), a method for recovery of injured cells, were determined at 1 h and 1, 3, 7, and 14 days. At 5ºC, Salmonella Typhimurium counts in untreated apple juice declined from 4 to 3 log CFU/mL in 7 days, and 2 log CFU/mL in 14 days. In treated samples, counts were reduced to 3 log CFU/mL at 3 days. Samples containing 100 ppm nisin and cinnamon, and 200 ppm nisin, with or without cinnamon, presented 1-2 log CFU/mL at day 7. Very little to no growth occurred at 14 days. At 20ºC, Salmonella Typhimurium counts in untreated apple juice decreased from 4 to 2 log CFU/mL in 3 days, <1 log CFU/mL in 7 days, and nondetectable in 14 days. Counts in samples with 200 ppm nisin and cinnamon were 1 log CFU/mL at 1 day, and in the other treated samples were 2-3 log CFU/mL. No growth occurred at 3, 7, and 14 days. The TAL method was as effective as TSA to recover injured cells. Treatment with nisin and cinnamon effectively inactivates Salmonella Typhimurium in apple juice.
Session 15D, Food Microbiology: Fruits and vegetables
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