Abstract

SHELF-LIFE STUDY OF TOMATO JUICE PRESERVED WITH LACTIC ACID BACTERIA

Ibe I. J.*, Chimereze N. C. and Sydney-Anuforo O.

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Abstract

Tomato is one of the most popular consumed vegetable crops worldwide mainly as fresh or processed products. The antimicrobial potentials of lactic acid bacteria metabolites against tomato paste spoilage microorganisms were evaluated. Cow milk and Tomato samples were purchased. The tomato samples were processed into tomato paste. Standard microbiological methods were used in isolation, microbial count and identification of organisms. Cow milk samples were used for the isolation of lactic acid bacteria. Antimicrobial effects of the isolated LAB metabolites were carried out on the spoilage isolates from tomato samples using the agar well diffusion method, while shelf-life study was done on the tomato juice samples using the LAB metabolites as biopreservative agents. The results showed total viable count ranged from 1.50 x 106cfu/ml - 1.3 x 106cfu/ml, the coliform count from 2.5 x 104cfu/ml – 1.1 x 103cfu/ml, while the fungal count was from 3.0 x 104cfu/ml – 1.5 x 104cfu/ml. The bacterial isolates were Proteus vulgaris, Lysinibacillus macroides, Staphylococcus aureus, Enterobacter cloacae and Klebsiella variicola, while the fungal isolates were Fusarium lichenicola and Aspergillus niger. LAB isolates from the cow milk samples were Lactobacillus fermentum M6, Lactobacillus fermentum LF-12 and Lactobacillus fermentum M8. The strains of Lactobacillus fermentum were able to grow at different temperature, pH and Nacl concentration and also produced antimicrobial compounds with Lactobacillus fermentum LF- 12 recording the highest lactic acid (0.98g/l), diacetyl (1.77g/l) and hydrogen perioxide (1.60g/l). The metabolites from strains of Lactobacillus fermentum were all potent against the spoilage microorganisms with zones of inhibition ranging from 2mm to 8mm. There were significant differences (p

Keywords: Lactic acid bacteria, Metabolites, Tomato juice, Spoilage organisms, Antimicrobial, Shelf life.