Selection of lactic acid bacteria as starter cultures for the manufacture of fermented vegetables

SAEZ, GABRIEL DARIO; ZÁRATE, GABRIELA; FLOMENBAUM, LEANDRO

S.M. DE TUCUMAN

Congreso; XII Congreso Argentino de Microbiología General; 2017

Asociación Civil de Microbiología General

Canned vegetables like pickles are well-accepted products consumed as appetizer or side dish with a main meal. Most fermented vegetable products marketed in the northwest of Argentina are traditionally obtained through a process of spontaneous fermentation carried out by the epiphytic microbes present on the raw materials that may include lactic acid bacteria (LAB). LAB contribute significantly to the flavor, texture, nutritional value and safety of fermented food products. In consequence, their addition as starter cultures for fermentation represents an important progress in the manufacture of high quality and reproducible products. At present, there are no industrial starters of autochthonous LAB for pickles fermentation in our region, which could provide the local market with products of appreciable organoleptic properties and longer shelf-life. Therefore, the objective of this work was to technologically characterize strains of LAB previously isolated from vegetables in order to select the most suitable as starters for the manufacture of fermented vegetables. For this purpose, six LAB strains isolated from pickles, olives and chesses made with unpasteurized milk and selected previously by their acidification rates, were identified by 16S rRNA gene sequencing and technological characterized regarding relevant properties for pickles manufacture such as: growth in the presence of increasing concentrations of NaCl (2, 4, 7 y 10%); at different pH (5.5, 5.0, 4.5 and 4) and production of antimicrobial substances against pathogens (Escherichia coli and Listeria sp.). The compatibility of the six LAB strains was tested by the production of inhibitory substances and set agar growth. Strains used in the present study were identified as Lactobacillus rhamnosus GS21 and GS43, L. plantarum GS31 and GS34, Weissella viridicens GS25 and W. paramesenteroides GS35. At initial pH 4.5 and 7% NaCl, the strains that showed the highest growth were L. plantarum GS34 and L. rhamnosus GS43. These microorganisms were also able to inhibit by acidity both pathogens tested and showed no incompatibility between each other that could prevent their use as mixed cultures. Properties exhibited by the selected LAB strains make them eligible as new starter cultures for obtaining fermented vegetable products with high hygienic and sensory quality.