Inhibitory Effect of Lactobacillus plantarum FL75 and Leuconostoc mesenteroides FL14 against Foodborne Pathogens in Artificially Contaminated Fermented Tomato Juices.

Aïssé Bah,Joana Bastos Barbosa,Hadda-Imene Ouzari,Paula Teixeira,Afef Najjari,Yosra Gharbi,Helena Albano,Abdellatif Boudabous,Imene Fhoula

doi:10.1155/2019/6937837

Aïssé Bah, Joana Bastos Barbosa + Show 7 more

Open Access

https://doi.org/10.1155/2019/6937837

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Abstract

Tomatoes and tomato based-foods contain beneficial microorganisms and various organic acids that have important nutritional values for human. The objective of this study was to access the physiochemical properties of fermented tomatoes juices and to evaluate the competitiveness of lactic acid bacteria (LAB) against Listeria monocytogenes, Listeria innocua, and Salmonella spp., in artificially contaminated tomato juice. Microbial counting (LAB, fungi Salmonella spp., and Listeria spp.) was performed after fermentation and weekly during storage. Different organic acids (Lactic, succinic, and acetic) and ethanol were also monitored using HPLC method. Color parameters were also determined. The results showed an increase of lactic and acetic acid content, during fermentation and storage of juices inoculated with Lactobacillus plantarum and Leuconostoc mesenteroides at 25°C. Besides, citric acid and ethanol revealed higher content at the end of storage compared to that registered at 4°C. The pH from tomatoes juices decreased from an initial value of 4.5 to below 3.2. Alongside, foodborne pathogen population was significantly suppressed in tomatoes juices when the samples were coinoculated with LAB strains. Moreover, the inhibition of Salmonella species was faster compared to that of Listeria. After four weeks of storage at 4°C, Lb. plantarum and Lc. mesenteroides showed high survival rate, while pathogenic bacteria, yeasts, and molds cell numbers decreased drastically in all the contaminated vials. This work highlights the efficiency of Lb. plantarum and Lc. mesenteroides as potential starters for developing nutritious and safe fermented tomato juice products.

Highlights

Tomatoes are one of the major vegetables widely used throughout the world, either in fresh or in processed form, including canned, sun-dried tomatoes, juices, ketchup, mashed tomatoes, sauces, and soups [1]
The matrices of fresh tomato contain autochthonous beneficial microbes (e.g., Lb. plantarum, Lc. mesenteroides) which may compete with pathogens and ensure extended shelf life [4, 5] Lactobacillus plantarum as well as other lactic acid bacteria (LAB) were widely used in biopreservation of different food matrices [6]
The objectives of this work were (i) to evaluate metabolites produced during fermentation and of storage of tomatoes juices, (ii) perform the microbiological analysis and viability of LAB used as starter, and (iii) test the antagonistic activity of LAB against foodborne pathogens in artificially contaminated vials

Summary

Introduction

Tomatoes are one of the major vegetables widely used throughout the world, either in fresh or in processed form, including canned, sun-dried tomatoes, juices, ketchup, mashed tomatoes, sauces, and soups [1]. Tomatoes juices are well recognized by their important nutritional values for human (low cholesterol, fiber and proteins, vitamins as well as β-carotene, potassium and lycopene, and high content of antioxidants) [2]. Pathogens (e.g., L. monocytogenes, E. coli, and Salmonella spp.) can be part of these populations and may cause food poisoning when eaten as raw product [3]. The matrices of fresh tomato contain autochthonous beneficial microbes (e.g., Lb. plantarum, Lc. mesenteroides) which may compete with pathogens and ensure extended shelf life [4, 5] Lactobacillus plantarum as well as other LAB were widely used in biopreservation of different food matrices [6]. Fermentation by using LAB as starter carries out acidification, [8], which leads to the decrease of pH

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