The effect of NaCl reduction in the microbiological quality of cracked green table olives of the Maçanilha Algarvia cultivar

Abstract

The present work aimed at studying the effect of the partial replacement of NaCl with KCl and CaCl2 of the fermenting brines on the microbiological quality of natural cracked green Maçanilha Algarvia table olives. Olives were fermented in different salt combinations (Brine 1—8% NaCl, Brine 2—4% NaCl 4% KCl, Brine 3—4% NaCl 4% CaCl2, Brine 4—4% KCl 4% CaCl2, and Brine 5—2.7% NaCl 2.7% KCl 2.7% CaCl2) and the abundance of yeasts and enterobacteria was determined. At the end of fermentation, the main microbial safety parameters were evaluated. Samples were analyzed according to standard methodologies and using Chromocult Agar (coliforms and Escherichia coli). The yeasts collected were grouped by restriction analysis of the ITS-5.8S rRNA gene and identified by partial sequencing of the 26S rRNA. Throughout the study, a decrease of the enterobacteria population was observed in all the fermentations, which was greater and faster in brines containing potassium and calcium. The main yeasts identified were Pichia membranaefaciens, Candida boidinii, Zygosaccharomyces mrakii, Priceomyces carsonii, Saccharomyces cerevisiae, Wickerhamomyces anomalus and the yeast-like fungus Galactomyces geotrichum. The highest yeast diversity was found in olives produced in Brines 1, 2 and 3 and the lowest in Brines 4 and 5, where only the species P. membranaefaciens, C. boidinii and G. geotrichum were identified. No Pseudomonas, E. coli, Salmonella, Staphylococcus aureus and Listeria monocytogenes were found in the table olives produced.