Cobrançosa Table Olive Fermentation as per the Portuguese Traditional Method, Using Potentially Probiotic Lactiplantibacillus pentosus i106 upon Alternative Inoculation Strategies

• Published in: Fermentation (Basel) 2023-01, Vol.9 (1), p.12
• Main Authors: Coimbra-Gomes, Joana, Reis, Patrícia J. M., Tavares, Tânia G., Silva, Afonso A., Mendes, Eulália, Casal, Susana, Malcata, Francisco Xavier, Macedo, Angela C.
• Format: Article
• Language: English
• Subjects: Cultivars; Cultural heritage; Fermentation; Food; Inoculation; Lactic acid bacteria; microbiological profiles; Microbiota; Microorganisms; Oleaceae; Olives; Probiotics; Salt; Sensory properties; Sodium chloride; starter culture; Starter cultures; table olives; Temperature; Water content
• ISSN: 2311-5637; 2311-5637
• DOI: 10.3390/fermentation9010012

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.