Lactic Acid Bacteria from Argentinean Fermented Foods: Isolation and Characterization for their Potential Use as Starters for Fermentation of Vegetables.

Gabriel D Sáez,Leandro Flomenbaum,Gabriela Zárate

doi:10.17113/ftb.56.03.18.5631

Abstract

SUMMARYLactic acid bacteria (LAB) improve the organoleptic, nutritional and physicochemical properties of artisanal foods. In this study, we selected 31 fermented dairy and vegetable foods marketed in Tucumán city, Argentina, as sources of LAB for the production of pickles. Sixty-four isolates presumptively identified as Lactobacillus strains were screened for relevant technological properties for production of fermented foods. Most strains showed moderate to good acidification (>0.04 pH units/h) and proteolytic capabilities (free aminoacids >1 mmol/L), produced diacetyl and/or acetoin and were resistant to 4% NaCl. Based on acid production and osmotolerance, we selected six LAB strains and identified them by 16S rDNA sequencing (97–100% identity) as: Lactobacillus rhamnosus CRL2159 and CRL2164, L. plantarum CRL2161 and CRL2162, Weissella viridescens CRL2160 and W. paramesenteroides CRL2163. Relevant properties for pickle manufacturing were further assessed. At an initial pH=4.5 and 7% NaCl, L. plantarum CRL2162 and L. rhamnosus CRL2164 performed the best with high growth and inhibitory activity against Escherichia coli and Listeria innocua. There was no obvious antagonism among the selected strains that would dismiss their use in mixed cultures. Properties of the selected LAB suggest their potential as starter cultures for obtaining standardized, fermented vegetable products of high quality. The development of these new industrial starters would increase the competitiveness of production and open the country’s frontiers in the canned vegetable market.

Highlights

Fermentation is a biological process widely used for food production and preservation
There is a great variety of fermented foods, most commercial Lactic acid bacteria (LAB) starter cultures are developed for the dairy industry and to a lesser extent for sausage production
In regards to the origin of the bacteria, similar proportions of LAB isolates were obtained from both environments (53 % from dairy and 47 % from pickles)

Summary

Introduction

Fermentation is a biological process widely used for food production and preservation. The fermentation technology used in food manufacturing has moved from artisanal practices to industrialized biotechnological processes that allow for the production of high quality standardized products. This change is possible because of the usage of starter cultures, which are pure or mixed cultures of microorganisms inoculated into a food matrix in order to replace its endogenous microbiota and improve the fermentation by enhancing nutritional and functional properties, organoleptic characteristics and safety [1]. When selecting LAB for food fermentations, different technological properties that could be relevant for the final product must be considered This properties include the acidifying, proteolytic and lipolytic activities that contribute to the preservation, flavour and nutritional quality of the product. Resistance to different stressful conditions, such as high salt concentrations, development at acidic pH and growth at high or low temperatures, are considered as selection criteria for the development

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