Do Best-Selected Strains Perform Table Olive Fermentation Better than Undefined Biodiverse Starters? A Comparative Study.

Antonio Paba,Piergiorgio Sedda,Marco Campus,Roberta Comunian,Alberto Angioni,Monica Bulla,Luigi Chessa,Elisabetta Daga

doi:10.3390/foods9020135

Antonio Paba, Piergiorgio Sedda + Show 6 more

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https://doi.org/10.3390/foods9020135

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Abstract

Twenty-seven Lactobacillus pentosus strains, and the undefined starter for table olives from which they were isolated, were characterised for their technological properties: tolerance to low temperature, high salt concentration, alkaline pH, and olive leaf extract; acidifying ability; oleuropein degradation; hydrogen peroxide and lactic acid production. Two strains with appropriate technological properties were selected. Then, table olive fermentation in vats, with the original starter, the selected strains, and without starter (spontaneous fermentation) were compared. Starters affected some texture profile parameters. The undefined culture resulted in the most effective Enterobacteriaceae reduction, acidification and olive debittering, while the selected strains batch showed the lowest antioxidant activity. Our results show that the best candidate strains cannot guarantee better fermentation performance than the undefined biodiverse mix from which they originate.

Highlights

Table olives are the most widely diffused traditional fermented vegetable product in the Mediterranean area [1]
A biodiverse L. pentosus starter culture (SIE, selected inoculum enrichment) obtained from a previous successful fermentation [16] and 27 L. pentosus strains, previously molecularly biotyped [17], were characterised for their technological features: 11 strains were isolated from the SIE starter; 14 came from vats of table olives inoculated with SIE; 2 from vats of table olives under natural fermentation
None of the isolates or the SIE starter culture were able to grow at 10 ◦ C

Summary

Introduction

Table olives are the most widely diffused traditional fermented vegetable product in the Mediterranean area [1]. Natural fermentation is carried out by soaking raw olives in brines (6%–10% NaCl), where environmental microflora colonizing olives, vats, and tools used in previous processes give rise to a spontaneous fermentation, driven mainly by lactic acid bacteria (LAB) and yeasts. In several productions, natural fermentation is replaced by the use of microbial starters, yeast- or LAB-based, to enhance the fermentation performances, speeding up the acidification of brines [2], preventing the proliferation of spoilage bacteria [5], or conferring probiotic characteristics to the product [6,7]. The microbial starters used for table olives can be made by few (or even one) species and strains, as in the case of the selected starter

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