29F-7 |
Antimicrobial effect of cranberry juice against Listeria monocytogenes |
R. BEVERLY, W. Prinyawiwatkul, and M. E. Janes. Dept. of Food Science, Louisiana State Univ. Agricultural Center, 111 Food Science Bldg., Baton Rouge, LA 70803-4200 The average consumer has become concerned with the microbial safety of ready-to-eat meat products because Listeria monocytogenes (LM) has caused a number of outbreaks and deaths associated with these products. Methods need to be developed to control or eliminate LM in these foods products. One possible solution would be the use of natural compounds such as cranberries. Cranberries contain phenolic compounds that inhibit microbial growth by disputing cell membrane function. The effects of cranberries on foodborne pathogens have not been reported. Our study evaluated the time and concentrations of cranberry juice (CJ) needed to effectively reduce Listeria monocytogenes ½a (LM) counts in vitro. A 16 h LM culture was separated into 1 ml fractions and centrifuged at 14,000 rpm for 10 min. The bacterial pellets were resuspended into different 1 ml concentrations of filtered CJ (27%, 24%, 22%, 19%, 16%, 14%, 2.7%, and 0.27%) and incubated at 37°C for 30, 60, 90, 120, or 150 min. Next the samples were spread plated onto UVM agar plates, incubated at 37°C for 48 h and CFU/ml determined. After 30 min in 27% CJ the LM counts of 10 log CFU/ml were reduced to non-detectable levels whereas with 2.7% juice the largest reduction occurred after 2h with approximately a 2 log CFU/ml reduction. At 0.27% CJ the LM counts were not significantly different from control levels. Conversely, concentration levels of 14% CJ reduced LM counts by 4 log CFU/ml, 16 % CJ reduced LM counts by 5 log CFU/ml, and 19-22% CJ reduced LM counts by 6 log CFU/ml. The most effective concentrations were 24-27% of CJ that reduced LM counts to non-detectable levels. Our study indicates that cranberry juice is very effective in reducing LM counts in vitro. Cranberries may be an effective alternative for the control of LM in ready-to-meat products.
Session 29F, Food Microbiology: Control of foodborne microorganisms by antimicrobials
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