Microbial community and volatilome changes in brines along the spontaneous fermentation of Spanish-style and natural-style green table olives (Manzanilla cultivar)

Microbial community and volatilome of brines were monitored during the spontaneous fermentations of Spanish-style and Natural-style green table olives from Manzanilla cultivar. Fermentation of olives in the Spanish style was carried out by lactic acid bacteria (LAB) and yeasts, whereas halophilic Gram-negative bacteria and archaea, along with yeasts, drove the fermentation in the Natural style. Clear differences between the two olive fermentations regarding physicochemical and biochemical features were found. Lactobacillus, Pichia, and Saccharomyces were the dominant microbial communities in the Spanish style, whereas Allidiomarina, Halomonas, Saccharomyces, Pichia, and Nakazawaea predominated in the Natural style. Numerous qualitative and quantitative differences in individual volatiles between both fermentations were found. The final products mainly differed in total amounts of volatile acids and carbonyl compounds. In addition, in each olive style, strong positive correlations were found between the dominant microbial communities and various volatile compounds, some of them previously reported as aroma-active compounds in table olives. The findings from this study provide a better understanding of each fermentation process and may help the development of controlled fermentations using starter cultures of bacteria and/or yeasts for the production of high-quality green table olives from Manzanilla cultivar.

Data on sensory profile of green Spanish-style table olives studied by Quantitative Descriptive Analysis

This article contains processed data related to the research published in “Sensory profile of green Spanish-style table olives according to cultivar and origin” [1]. It provides information on the physicochemical characteristics of the analysed samples and the results of the multivariate analysis used in the above-commented paper. Particularly, it includes: i) the values of pH, titratable acidity, combined acidity, and NaCl for batches according to samples, ii) the scores given to each descriptor by the panelists according to samples, iii) the histogram of the overall scores for descriptor, iv) the boxplot of descriptors over samples, v) the effect of samples and contribution of panelists to the interaction sample∙panelist, vi) correlation between the panelists and the whole panel, vii) panelist performance, viii) panel repeatability, ix) sensory profile of samples (spider graph), x) adjusted means for descriptor according to samples, xi) prevalence of descriptors on samples, xii) product effect as assessed by p-value.

Fermentation profile of green Spanish-style Manzanilla olives according to NaCl content in brine

This work studies the effects of the partial substitution of NaCl with potassium and calcium chloride salts on the fermentation profile of Spanish-style green Manzanilla olives. For this purpose, response surface methodology based in an enlarged simplex centroid mixture design with constrain (∑salts = 100 g/L) was used. Regarding to physicochemical characteristics, pH decreased when CaCl2 increased, titratable acidity was lower in presence of KCl while combined acidity increased as the contents of KCl and CaCl2 were close to the barycentre of the experiment (∼33.33% each salt). Regarding to microbiological profile, Enterobacteriaceae growth was slight stimulated in presence of high CaCl2 contents, yeast patterns were not linked to the initial brine compositions, while the maximum lactic acid bacteria population decreased slightly as KCl and CaCl2 increased in the proportion 1:1, although a moderate (equilibrated) content of both may be stimulating. Results obtained in this work show that Spanish-style green Manzanilla cv. can be fermented in diverse mixtures of chloride salts, albeit the initial CaCl2 should be limited to 20-30 g/L to prevent excessive Enterobacteriaceae growth; combining it with a similar proportion of KCl may also improve LAB predominance.