Physicochemical and microbiological profile of packed table olives

Exploring bacteria diversity in commercialized table olive biofilms by metataxonomic and compositional data analysis

In this work, a total of 72 samples of non-thermally treated commercial table olives were obtained from different markets of the world. Then, prokaryotic diversity in olive biofilms was investigated by metataxonomic analysis. A total of 660 different OTUs were obtained, belonging to Archaea (2.12%) and Bacteria domains (97.88%). From these, 41 OTUs with a proportion of sequences ≥ 0.01% were studied by compositional data analysis. Only two genera were found in all samples, Lactobacillus, which was the predominant bacteria in the biofilm consortium (median 54.99%), and Pediococcus (26.09%). Celerinatantimonas, Leuconostoc, Alkalibacterium, Pseudomonas, Marinilactibacillus, Weissella, and the family Enterobacteriaceae were also present in at least 80% of samples. Regarding foodborne pathogens, only Enterobacteriaceae, Vibrio, and Staphylococcus were detected in at least 91.66%, 75.00%, and 54.10% of samples, respectively, but their median values were always below 0.15%. Compositional data analysis allowed discriminating between lye treated and natural olive samples, as well as between olives packaged in glass, PET and plastic bags. Leuconostoc, Celerinatantimonas, and Alkalibacterium were the bacteria genera with a higher discriminant power among samples. These results expand our knowledge of the bacteria diversity in olive biofilms, providing information about the sanitary and hygienic status of this ready-to-eat fermented vegetable.

Antioxidant Effect of Natural Table Olives Phenolic Extract Against Oxidative Stress and Membrane Damage in Enterocyte-Like Cells

The phenolic fraction of a naturally fermented cultivar of table olives, "Tonda di Cagliari," was investigated for the ability to protect Caco-2 cells against oxidative stress and membrane damage induced by tert-butyl hydroperoxyde (TBH). TBH exposure resulted in an alteration of cellular redox status, with an increase in reactive oxygen species (ROS) and a decrease in reduced glutathione (GSH) level. A loss of the epithelial integrity, as indicated by the decrease of the transepithelial electrical resistance value, was also observed over time, together with an intense lipid peroxidation process. The olives phenolic extract significantly counteracted ROS generation and subsequent alteration of monolayer integrity and membrane oxidative damage. The protective action of the extract is likely due to the scavenging ability of its main components, as hydroxytyrosol, oleuropein, and verbascoside among the secoiridoids and derivatives. Since olives phenolic compounds concentrate in the intestinal lumen, they may be a useful tool in the prevention of intestinal disorders related to oxidative damage.

Effect of zinc formulations, sodium chloride, and hydroxytyrosol on the growth/no-growth boundaries of table olive related yeasts

This study uses a mathematical approach to assessing the inhibitory effect of Zn(2)(+)(0-10 mM, obtained from ZnCl2 and ZnSO4) in presence of NaCl (0-8%) and hydroxytyrosol (0-2588 mg/L), on a yeast cocktail formed by species Pichia galeiformis, Pichia kudriavzevii, Pichia manshurica and Candida thaimueangensis obtained from spoilt green olive packages. The logistic/probabilistic models were built in laboratory medium using a total of 1980 responses (1188 for NaCl and 792 for hydroxytyrosol). ZnCl2 showed significantly higher inhibitory effect than ZnSO4 in the presence of both NaCl (p < 0.033) and hydroxytyrosol (p < 0.009). NaCl did not interfere the effect of Zn(2)(+)while hydroxytyrosol, at high levels, had a slight antagonistic effect. According to models, Zn(2)(+)inhibits (p = 0.01) the yeast cocktail in the range 4.5-5.0 mM for ZnCl2, or 8.5-9.5 mM for ZnSO4. Therefore, this work confirms the fungicidal activity of zinc compounds (mainly ZnCl2) in synthetic medium, and also shows that the loss of zinc effectiveness in real green Spanish-style olive packaging is not due to the presence of NaCl or hydroxytyrosol, two of the most abundant chemical compounds in the product.

Factors influencing phenolic compounds in table olives (Olea europaea)

The Mediterranean diet appears to be associated with a reduced risk of several chronic diseases including cancer and cardiovascular and Alzheimer's diseases. Olive products (mainly olive oil and table olives) are important components of the Mediterranean diet. Olives contain a range of phenolic compounds; these natural antioxidants may contribute to the prevention of these chronic conditions. Consequently, the consumption of table olives and olive oil continues to increase worldwide by health-conscious consumers. There are numerous factors that can affect the phenolics in table olives including the cultivar, degree of ripening, and, importantly, the methods used for curing and processing table olives. The predominant phenolic compound found in fresh olive is the bitter secoiridoid oleuropein. Table olive processing decreases levels of oleuropein with concomitant increases in the hydrolysis products hydroxytyrosol and tyrosol. Many of the health benefits reported for olives are thought to be associated with the levels of hydroxytyrosol. Herein the pre- and post-harvest factors influencing the phenolics in olives, debittering methods, and health benefits of phenolics in table olives are reviewed.

Multivariate analysis for the evaluation of fiber, sugars, and organic acids in commercial presentations of table olives

Table olives constitute an important part of the Mediterranean diet and the diet of many non-olive-producing countries. The aim of this work was to determine the fiber, sugar, and organic acid contents in Spanish commercial presentations of table olives and characterize them by means of a multivariate analysis. The selection of variables was carried out on the basis of a canonical analysis and their classification, according to processing styles and cultivars, through a linear discriminant analysis. Values of dietary fiber in table olives ranged from 2 to 5 g/100 g edible portion (e.p.). Some stuffing materials (almond, hot red pepper, and hazelnut) or the addition of capers produced a significant increase in the total dietary fiber in green olives. Glucose, fructose, and mannitol were usually found in the ranges of 0-55, 0-70, and 0-107 mg/100 g e.p., respectively. Succinic acid was detected only in green and directly brined olives (0-40 mg/100 g e.p.), while lactic and acetic acids were used within the ranges of 0-681 and 5-492.8 mg/100 g e.p., respectively. A multivariate analysis showed that fiber, mannitol, and succinic, lactic, and acetic acids can be used to discriminate between processing styles (95.5% correct assignations) and cultivars (61.20%). Current data can also be used in the evaluation of the dietary value of table olives.

Physicochemical, microbiological, and organoleptic profiles of Greek table olives from retail outlets

The physicochemical, microbiological, and organoleptic profile of different commercial table olive products from retail outlets was studied. Average pH values were 4.00, 3.96, and 4.31 for Spanish-style green, naturally black, and dry-salted olives, respectively, while salt content was 6.21, 7.34, and 8.00% for the same commercial products. Mean values for titratable acidity were 0.53 and 0.63% (wt/vol) for green and naturally black olives. In general, mean values for pH, titratable acidity, and salt content were in accordance with the requirements established by the International Olive Oil Council (IOOC) for the trade of table olives, although considerable variation was observed within individual olive samples. Salt content of dry-salted olives did not meet the minimum limit of 10% established by the IOOC. The dominant microbiota consisted of lactic acid bacteria and yeasts. Their population was less than 10(9) CFU ml(-1), as stipulated by the IOOC standard for fermented olives held in bulk in a covering liquid. These microorganisms come from the natural microbiota found in spontaneous fermentations and impose no risk to human health. No enterobacteria, pseudomonads, Bacillus cereus, or Clostridium perfringens were detected in any of the samples given the physicochemical characteristics found. The organoleptic profile varied greatly according to processing style and commercial preparation. Green olives had more uniform sensory characteristics than naturally black and dry-salted olives. The most important attributes that influenced the judgment of the panelists were salt content and crispness of the olives.