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In this work, we have used a metataxonomic analysis to study the bacterial biodiversity in three types of commercial dressing and ingredients habitually used in table olive packaging. The bioinformatics analysis showed that salt samples (marine and spring) had the highest biodiversity indexes, followed by the aromatic herbs (thyme, oregano, and fennel) and finally by fermented dressing samples (garlic, pepper, and pepper paste). In salt samples, a significant high presence of Cytophagia , Sphingobacteria, Deltaproteobacteria and Halobacteria classes was observed. On the contrary, the presence of Bacilli class in fermented dressing samples was significantly higher compared to the other samples. Finally, the abundance of Gammaproteobacteria was statistically higher in the samples of herbs. At genus or family taxonomic level, Pseudomonas and diverse non-assigned genus of the Enterobacteriaceae family predominated in many samples of herbs. In fermented dressing samples, a diverse genus belonging to the Enterobacteriaceae family appeared in a high relative abundance in pepper paste and garlic, and the presence of Vibrio sp. was detected in pepper. However, Lactobacillus, Weisella, and Pediococcus were the predominant genera found in many of these fermented samples. Salinibacter was the most representative genus in both types of salt samples. Multivariate analysis (PCA) of the metataxonomic data sets discriminated well the samples belonging to the three different groups, showing a high proportion of sequences shared by samples-group. This survey reports for the first time the presence of new bacterial species not previously related to table olive processing, as well as the presence of others which could compromise the stability of olive packaging. • Metataxonomic analysis has provided a deep knowledge of the microbiota present in olive dressing. • Pseudomonas and diverse non-assigned genus of Enterobacteriaceae predominated in aromatic herbs. • Lactobacillus , Weisella, and Pediococcus were the predominant genera found in many fermented dressing samples. • Salinibacter was the most representative genus found in samples of salt. • Olive dressing includes spoilage microorganisms that may alter the stability of table olive packaging. [ABSTRACT FROM AUTHOR]

This work reports the survival (challenge tests) of foodborne pathogen species ( Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Salmonella enterica ) in Aloreña de Málaga table olive brines. The inhibitions were fit using a log-linear model with tail implemented in GInaFIT excel software. The olive brine had a considerable inhibitory effect on the pathogens. The residual (final) populations ( Fp ) after 24 h was below detection limit (<1.30 log 10 cfu/mL) for all species assayed. The maximum death rate ( k max ) was 9.98, 51.37, 38.35 and 53.01 h −1 , while the time for 4 log 10 reductions ( 4D r ) was 0.96, 0.36, 0.36 and 0.24 h for E. coli, S. aureus, L. monocytogenes and S. enterica, respectively. Brine dilutions increased Fp and 4Dr , while decreased k max . A cluster analysis showed that E. coli had an overall quite different behaviour being the most resistant species, but the others bacteria behaved similarly, especially S. aureus and S. enterica . Partial Least Squares regression showed that the most influential phenols on microbial survival were EDA (dialdehydic form of decarboxymethyl elenolic acid), HyEDA (EDA linked to hydroxytyrosol), hydroxytyrosol 4-glucoside, tyrosol, and oleoside 11-methyl ester. Results confirm the adverse habitats of table olives for foodborne pathogenic microorganisms. [ABSTRACT FROM AUTHOR]

In the present study, a dose-response model was used to investigate the susceptibility (NIC) and resistance (MIC) of the lactic acid bacteria and yeast populations with respect to five chemical preservatives (fumaric and pyruvic acids, cinnamaldehyde, sodium metabisulphite and natamycin) with potential application in table olives. Results were compared with respect to potassium sorbate, a well-known preservative habitually used in olive packaging. Sodium metabisulphite was the most efficient preservative to control lactic acid bacteria growth (MIC, 50 ppm), followed by cinnamaldehyde (1060 ppm) while pyruvic acid required higher concentrations (3211 ppm). Natamycin (25 ppm) was highly efficient against yeasts, followed by cinnamaldehyde (125 ppm), potassium sorbate (553 ppm), sodium metabisulphite (772 ppm) and pyruvic acid (3038 ppm). Fumaric acid, in the range assayed (0–2000 ppm), did not show any inhibitory effect against these two microbial groups. This survey presents for the first time a comparative study of the efficiency of potential preservatives to control the growth of table olive related microorganisms. Further studies should be performed to validate their effects and interactions in the food matrix. [ABSTRACT FROM AUTHOR]

This work focuses on the persistence of the putative probiotic bacteria Lactobacillus pentosus TOMC- LAB2 on green Spanish-style Manzanilla olives according to different packaging conditions and storage temperatures. The lactic acid bacteria population decreased with time but the highest survival counts (and lowest yeasts) at the end of storage (8 months) were observed in plastic pouches under nitrogen atmosphere and glass jars with brine stored at 20°C. Molecular techniques showed a 100% presence of the putative probiotic bacteria in biofilms adhered to olive epidermis, while it was absent in PPB (plastic pouches with brine) and in olives stored at 7°C. No changes in NaCl, pH or combined acidity were observed during the storage except for a slight increase in titratable acidity at 20°C. The color of the fruits was stable but degraded at 20°C for olives in plastic pouches with brine. [ABSTRACT FROM AUTHOR]

In this work, a total of 72 commercial table olive packages obtained from different international markets were analysed to determine their fungal biodiversity. Viable fungal counts ranged from the detection threshold (<1.6 log 10 CFU/g in 25% of cases) to a maximum of 5.86 log 10 CFU/g. Assignation of fungal taxonomy was carried out through a metataxonomic analysis of the ITS region, which revealed that almost half of the total sequences obtained from all packages corresponded to the Pichia genus (44.08%), followed by Citeromyces (14.45%), Candida (8.07%), and Wickerhamomyces (6.95%). In lower proportions were also detected other genera such as Starmerella (3.60%), Saccharomyces (2.24%), Debaryomyces (2.08%), and Dekkera (2.05%). The statistical analysis allowed to link certain taxa to specific types of elaboration (lye treated, green, and black natural olives), presentation (pitted, whole, or sliced samples), and packaging material/system (glass, PET, plastic bags, and vacuum). Likewise, Zygotorulaspora genus was especially sensitive to the presence of potassium sorbate, while other genera such as Sporobolomyces , Moniliella , and Gibellulopsis were more abundant in packages treated with this preservative. Lastly, potential pathogenic fungal genera such as Alternaria, Kodamaea, Lodderomyces, Malasessia, or Aspergillus were detected in low proportions (<0.3%), although with higher representation in some individual samples. Our results contribute to improving our knowledge of the fungal population associated with this ready-to-eat fermented vegetable, providing us a strong tool to assess the safety, stability, and quality of the final product. • Metataxonomic approach of ITS region was applied in global commercial olive packages. • Half of total sequences obtained from all packages corresponded to the Pichia genus. • Potential pathogenic fungi were detected in high representation in some samples. • The presence of certain fungal taxa was influenced by the packaging conditions. [ABSTRACT FROM AUTHOR]

After moisture, fat is the major constituent of table olives. However, scarce studies have been carried out to determine the influence of microorganisms and type of processing on the modification of their quality indexes. The present survey studies the influence of lipolytic ( Candida boidinii TOMC Y5 and Wickerhamomyces anomalus TOMC Y10) and nonlipolytic ( Debaryomyces etchellsii TOMC Y9 and Pichia galeiformis TOMC Y27) yeasts on the oil quality indexes of Manzanilla and Hojiblanca green fruits processed as directly brined and lye-treated table olives. Overall, the inocula scarcely used available sugars, except the lipolytic C. boidinii strain in lye-treated olives. Acetic acid production was limited in all conditions, except for the D. etchellsii strain in directly brined Manzanilla fruits. Ethanol formation was also reduced, although the W. anomalus (in both types of elaboration) and the C. boidinii (in lye-treated olives) strains produced significantly higher proportions. Apparently, changes in the oil quality indexes of processed olives were not related to the presence of yeasts, and hence, could have been caused by the endogenous activity of the fruits. A principal component analysis using the microbiological, physicochemical, and oil quality data supported this hypothesis, grouping treatments according to olive variety and type of elaboration, while segregation due to yeast inocula was not observed. [ABSTRACT FROM AUTHOR]