Search

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]

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]