Biocontrol of Listeria monocytogenes ATCC 7644 in fresh tomato with Probiotics

Abstract

The effectiveness of probiotics Lactobacillus bulgarius and Streptococcus salivarius as biocontrol agents against Listeria monocytogenes ATCC 7644 in fresh tomato throughout storage and their effect on the physicochemical properties of tomato was evaluated. Tomato samples were cut into wedges and inoculated with 108 CFU/ml of Listeria monocytogenes ATCC 7644, thereafter inoculated with L.bulgaricus and S.salivarius separately. Tomato was also inoculated with probiotics L.bulgaricus and S.salivarius without inoculation of L.monocytogenes. Nutrient broth was prepared and inoculated with 108 CFU/ml of L.monocytogenes ATCC 7644 and thereafter inoculated with L.bulgaricus and S.salivarius separately after which all treatments were stored at 4°C for 72 hours. Chlorine was used as a control and compared against probiotics. L. monocytogenes counts taken during storage period in nutrient broth showed that L. bulgaricus had a 2.19 log reduction and S. salivarius had a 1.65 log reduction. The tomato study showed that L. bulgaricus had a 3.15 log reduction and S.salivarius had a 3.01 log reduction. Physicochemical properties of tomato were not affected (p > 0.05) by treatment with probiotics when compared to control. Statistical analysis showed a significant difference between both probiotics and chlorine in tomato. This research indicated that L.bulgaricus and S. salivarius could potentially be used as eco-friendly biocontrol agents in the produce industry.