50 Páginas; 3 Tablas; 3 FigurasThe volatile profiles of Spanish-style green table olives elaborated with Manzanilla, Gordal and Hojiblanca cultivars grown at different locations in Spain were established by solid phase micro-extraction (SPME) and gas chromatography coupled to mass spectrometry (GC–MS). A total of 102 volatile compounds were identified, belonging to distinct chemical classes, and 20 of them are reported for the first time in table olives. The headspace profile was predominated by alcohols and phenols, followed by acids and esters, whereas the relative amounts of the remaining classes were quite lower (< 5% in general). The principal compounds characterizing the headspace for most samples were p-creosol, phenylethyl alcohol, acetic acid, ethanol, benzyl alcohol, ethyl acetate, and (Z)-3-hexen-1-ol. Significant differences in the proportions of volatile compounds between samples from the Gordal cultivar and those from Manzanilla and Hojiblanca cultivars were detected and statistically visualized by principal component analysis (PCA). Among all the identified compounds, only (E)-2-decenal showed significant differences between the three cultivars without being significantly affected by locations where the fruits were grown.This work was supported by the Ministry of Economy and Competitiveness from the Spanish government through Project AGL2014-54048-R, partially financed by the European Regional Development Fund (ERDF).Peer reviewe

The effects of the main steps of Spanish-style processing (alkaline treatment and fermentation) on the volatile composition of cv. Manzanilla green olives were studied. Both spontaneous and controlled fermentations were considered. In the latter case, a Lactobacillus pentosus strain from green olive fermentation brine was used as starter culture. The volatile profile was determined by headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). Most of the volatile compounds detected in fresh olives decreased or were undetected after alkaline treatment, while several compounds (mostly acetic acid, 2-methylbutanoic acid, and ethanol) were formed as a result of this treatment. Over 50 new volatile components, mostly esters and phenols, appeared as a result of fermentation. The most outstanding finding was a considerable increase in 4-ethyl phenol (almost 100-fold increase) in inoculated olives compared to the uninoculated product. However, a sensory panel did not find significant differences in odor perception.

The aim of the present study was to assess the malodorous spoilages of Spanish-style green table olives through microbial and metabolite composition using current measuring techniques (e.g., high-throughput DNA sequencing, headspace solid-phase microextraction combined with gas chromatography-mass spectrometry). Under different alkaline and washing conditions, the spoilage fermentations were reproduced with Gordal and Manzanilla olive cultivars using a low salt concentration (71 g L⁻¹ NaCl) in the initial brine. The degradation of lactic acid and significant increases in volatile fatty acids and phenols were found in all the spoiled samples in comparison with the unspoiled control samples. According to high-throughput DNA sequencing, Cardiobacteriaceae and Ruminococcus were the dominant bacteria in the spoiled samples. PLS regression and Pearson’s correlation coefficient analyses revealed positive and negative correlations among microbial communities, metabolites, and sensory spoilage descriptors. Notably, the “zapatera” descriptor was significantly associated with Propionibacterium, which was positively correlated with acetic acid, propionic acid, succinic acid, and methyl propanoate; while the “butyric” descriptor exhibited a significant positive relationship with the genus Ruminococcus, which gave an almost significant correlation with propionic and butyric acids.

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.

The volatile profile of Spanish-style green table olives after fermentation and the changes in volatile compounds that occurred as a result of the post-fermentation and subsequent packing stage were explored by solid phase micro-extraction (SPME) and gas chromatography coupled to mass spectrometry (GC-MS). Three olive cultivars (Manzanilla, Gordal, and Hojiblanca) were processed and olive samples were taken at three different times throughout the elaboration: after fermentation, after post-fermentation, and after packing. A total of 132 volatile compounds were identified, including 10 phenols, 25 alcohols, 11 acids, 39 esters, 8 hydrocarbons, 14 carbonyl compounds, 17 terpenes, and 6 other compounds. A varying number of compounds from each chemical family underwent significant changes because of the post-fermentation and packing stages. Among them, some typical reaction products of lipid oxidation (e.g. (E)-2-decenal and (E,E)-2,4-decadienal) increased with the post-fermentation in Manzanilla cultivar, and also as a result of packing in all three cultivars.