New procedure to pre-select lactic acid bacteria able to control table-olive fermentation

Andrea Caridi,Alessandra Martorana,Amalia Piscopo,Alessandra De Bruno,Felice Panebianco,Rossana Sidari

doi:10.4025/actascitechnol.v44i1.57309

Andrea Caridi, Alessandra Martorana + Show 4 more

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https://doi.org/10.4025/actascitechnol.v44i1.57309

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Abstract

Using 35 artisanal Calabrian table-olive brines, 153 strains of lactic acid bacteria were isolated. A screening procedure was designed, involving the following steps: 1) Gram stain, cellular morphology, homolactic fermentation, acidifying activity in MRS broth; 2) growth in olive paste with NaCl 11%; 3) increase of the antioxidant activity; 4) identification of the best strains. The proposed procedure allows an evaluation of the technological aptitude of lactic acid bacteria to ferment table olives excluding, cheaply and easily, all those strains definitely unable to act as starter. The use of olive paste as a screening medium allows the resistance of the new isolates against olive phenolic compounds to be tested. The selection of strains able to increase the antioxidant power of olive paste can improve the shelf-life of table olives.

Highlights

Table olives are traditional fermented products widespread in Europe, with Spain, Greece, and Italy being the main producers (Bleve et al, 2015)
Lactic acid bacteria (LAB) are responsible for a pH decrease, which inhibits the growth of pathogenic and spoilage microorganisms (Hurtado, Reguant, Bordons, & Rozès, 2012), for oleuropein hydrolysis, that removes the bitter taste of the fruit by producing hydroxytirosol (Kaltsa, Papaliaga, Papaioannou, & Kotzekidou, 2015; Ghabbour et al, 2016; Ramírez, Brenes, Castro, Romero, & Medina, 2017), and for the production of compounds that confer aroma and flavour to the final product
The aim of the present study was to develop a screening procedure allowing to and cheaply exclude all those strains definitely unable to act as a starter culture

Summary

Introduction

Table olives are traditional fermented products widespread in Europe, with Spain, Greece, and Italy being the main producers (Bleve et al, 2015). Lactic acid bacteria (LAB) and yeasts determine the table-olive fermentation process (Arroyo-López et al, 2012). Yeasts play a role in flavour - since they can produce metabolites such as ethanol, glycerol, higher alcohols, and esters - and in texture formation. They help the degradation of phenolic compounds through esterase activity; they can synthesize bioactive compounds with antioxidant activity, other than synthesising vitamins, amino acids and purines that are helpful for LAB growth. Several yeasts can cause softening and gas-pocket spoilage of fruits; others can induce production of low-pigmented table olives, by adsorbing phenolic compounds responsible for their colour (Caridi, 2020)

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