Physico-chemical and microbiological characterization of spontaneous fermentation of Cellina di Nardò and Leccino table olives.

Gianluca Bleve,Stefania De Domenico,Ezio Perbellini,Antonio F Logrieco,Francesca A Ramires,Giovanni Mita,Francesco Grieco,Miriana Durante,Maria S Cappello,Maria Tasioula-Margari,Maria Tufariello

doi:10.3389/fmicb.2014.00570

Abstract

Table olives are one of the most important traditional fermented vegetables in Europe and their world consumption is constantly increasing. In the Greek style, table olives are obtained by spontaneous fermentations, without any chemical debittering treatment. Evolution of sugars, organic acids, alcohols, mono, and polyphenol compounds and volatile compounds associated with the fermentative metabolism of yeasts and bacteria throughout the natural fermentation process of the two Italian olive cultivars Cellina di Nardò and Leccino were determined. A protocol was developed and applied aimed at the technological characterization of lactic acid bacteria (LAB) and yeast strains as possible candidate autochthonous starters for table olive fermentation from Cellina di Nardò and Leccino cultivars. The study of the main physic-chemical parameters and volatile compounds during fermentation helped to determine chemical descriptors that may be suitable for monitoring olive fermentation. In both the analyzed table olive cultivars, aldehydes proved to be closely related to the first stage of fermentation (30 days), while higher alcohols (2-methyl-1-propanol; 3-methyl-1-butanol), styrene, and o-cymene were associated with the middle stage of fermentation (90 days) and acetate esters with the final step of olive fermentation (180 days).

Highlights

Olive production is considered one of the major agronomic practices of Mediterranean countries such as Italy, Greece and Spain that together supply almost 30% of world olive annual production (IOC, 2014)
ISOLATION OF MICROBIAL POPULATION To isolate epiphytic yeasts, Enterobacteriaceae and lactic acid bacteria (LAB), a sample consisting of 15 olives for Leccino (32,41 g) and 20 olives of Cellina di Nardò (32,62 g) and 50 ml of brine was stirred on a rotary shaker at 200 rpm for 30 min
In Leccino table olives, LAB were present at a concentration of 3.3 × 102 CFU/g, while Enterobacteriaceae were not detectable

Summary

Introduction

Olive production is considered one of the major agronomic practices of Mediterranean countries such as Italy, Greece and Spain that together supply almost 30% of world olive annual production (IOC, 2014). Table olives are one of the most important traditional fermented vegetables in Southern European countries and their consumption is constantly increasing. Produces about 76,000 tons/year of table olives, which is 3.1% of world and 10.3% of European Union production, respectively. A cultivar originary from Tuscany and Umbria regions (Central Italy), is the most widespread dual-purpose olive variety in the world, due to its exceptional adaptability to different growing conditions (Vossen, 2007). Cellina di Nardò is an olive cultivar autochthonous of Salento (Apulia, Southern Italy). The production of this traditional cultivar is about 180,000 tons per year.

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