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The probiotic features of Lactiplantibacillus (L.) pentosus and L. paraplantarum strains, endogenous in Cobrançosa table olives from northeast Portugal, were assessed in terms of functional properties and health benefits. Fourteen lactic acid bacteria strains were compared with Lacticaseibacillus casei from a commercial brand of probiotic yoghurt and L. pentosus B281 from Greek probiotic table olives, in attempts to select strains with higher probiotic performances than those references. For functional properties, the i53 and i106 strains, respectively, exhibited: 22.2 ± 2.2% and 23.0 ± 2.2% for Caco-2 cell adhesion capacity; 21.6 ± 7.8% and 21.5 ± 1.4% for hydrophobicity; 93.0 ± 3.0% and 88.5 ± 4.5% for autoaggregation ability by 24 h of incubation; and ability to co-aggregate with selected pathogens—from 29 to 40% to Gram+ (e.g., Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212); and from 16 to 44% for Gram− (e.g., Escherichia coli ATCC 25922 and Salmonella enteritidis ATCC 25928). The strains proved to be resistant (i.e., halo zone ≤14 mm) to some antibiotics (e.g., vancomycin, ofloxacin, and streptomycin), but susceptible (i.e., halo zone ≥ 20 mm) to others (e.g., ampicillin and cephalothin). The strains exhibited health-beneficial enzymatic activity (such as acid phosphatase and naphthol-AS-BI-phosphohydrolase), but not health-harmful enzymatic activity (such as β-glucuronidase and N-acetyl-β-glucosaminidase). Additionally, the antioxidant activity and cholesterol assimilation features, respectively, of the strains were 19.6 ± 2.8% and 77.5 ± 0.5% for i53, and 19.6 ± 1.8% and 72.2 ± 0.9% for i106. This study indicated that the addition of L. pentosus strains i53 and/or i106 to Cobrançosa table olives is likely to enhance the added value of the final product, in view of the associated potential benefits upon human health.

Spontaneous fermentation of table olives, as per a traditional Mediterranean process, is still performed empirically; hence, final product quality is somewhat unpredictable. Our main goal was to validate an endogenous (potentially probiotic) lactic acid bacterium strain in Cobrançosa table olives as a vector for a more standardized process, further adding commercial value to the olives themselves. The traditional Portuguese fermentation process typically consists of two stages: sweetening, when olives are periodically washed with spring water to different proportions, and salting, when water is no longer changed, but salt is gradually added to the brine, up to 7–10% (w/w). Lactiplantibacillus pentosus i106 was inoculated as follows: (plan A) 2020/21 harvest, with 0, 3, 5, and 7% (w/v) NaCl, without sweetening; (plan B) 2020/21 harvest, with 5 and 7% (w/v) NaCl, during salting and sweetening; and (plan C) 2019/20 harvest, with 5% (w/v) salt, and sweetening and salting. Microbiological, physical, and biochemical evolutions were monitored for 8 months, and final nutritional and sensory features were duly assessed. Compared to the control, lactic acid bacteria (LAB) predominated over yeasts only if deliberately inoculated; however strain viability was hindered above 5% (w/w) NaCl, and LAB inhibited enterobacteria. Degradation of (bitter) oleuropein to hydroxytyrosol and verbascoside was faster upon inoculation. Color-changing olives from the 2020/21 harvest exhibited higher fat content and lower water content compared to green ones (2019/20 harvest), and different salt levels and inoculation moments produced distinct sensory properties. The best protocol was plan C, in terms of overall eating quality; hence, the addition of Lpb. pentosus i106 provides benefits as a supplementary additive (or adjunct culture), rather than a starter culture.

Current market trends point at increasing demand for functional foods, namely those carrying probiotics. In the case of table olives, presence of probiotics would convey a competitive advantage to Mediterranean-based diets, already established for their cultural heritage and gastronomic character. This work assessed the safety and resistance to gastrointestinal digestion of 19 native LAB strains from Cobrançosa table olives. Strains were identified via molecular sequencing (4 fingerprints/10 strains for Lactiplantibacillus pentosus, and 2 fingerprints/9 strains for L. paraplantarum), and exposed to simulated gastrointestinal fluids, as per the INFOGEST in vitro protocol with modifications. None of those strains proved dangerous for human consumption. Survivability to the gastrointestinal resistance test ranged from 29% to 70%, with strain-dependent variability. L. paraplantarum i18, i27, and i102, and L. pentosus i10 and i11 exhibited statistically lower survival rates (29–35%) than probiotic the Greek table olive reference strain L. pentosus B281 (53%). Among the other strains, L. paraplantarum i101 and L. pentosus i53 and i106 showed the highest survival rates but were not significantly different from the strain of Lacticaseibacillus casei isolated from commercial probiotic yoghurt (65–70%). In vitro results proved that strains retrieved from fermenting cultivar Cobrançosa possess the potential to be claimed as probiotics—thus deserving further attention toward the development of a specific starter culture.

Our major goal was the physicochemical, biochemical and microbiological characterization of Cobrançosa table olives, as support for the eventual granting of a PDO status. Seven producers were accordingly sampled throughout eleven months. Brines were analyzed for pH, salinity, acidity, and organic and phenolic compounds. Yeasts and Latic Acid Bacteria (LAB) were enumerated, and the dominant strains duly identified. Despite process variabilities, two stages appear to be shared by all manufacturers: sweetening—the renewal of water to remove bitter compounds; and salting—gradual addition of salt to brine for preservation. Yeasts dominated during sweetening, but LAB tended to be similar in viable counts (7 log CFU/mL) by the end of salting. Lactiplantibacillus (Lpb.) pentosus, Lpb. paraplantarum, Pediococcus parvulus, and Oenococcus kitaharae were the most abundant LAB found, together with an average pH of 4.1 and 6–9% for salt content. All organic acids exhibited an inverted parabolic evolution, with maxima of 3450 mg/L for lactic and 4000 mg/L for succinic by 3 months, and 2750 mg/L for acetic and 2950 mg/L for citric by 4 months. Oleuropein levels were affected by the frequency of brine renewal but decreased from 1350 to 700 mg/L, with hydroxityrosol and tyrosol increasing from 10 to 2000 mg/L and 2 to 550 mg/L, respectively, within 11 months.