Inoculated fermentation of cv. Conservolea natural black olives with multifunctional starter cultures in reduced-sodium brines

The purpose of this research was to investigate the fermentation of Conservolea variety natural black olives using two lactic acid bacteria (LAB) with multifunctional potential as starter cultures. Moreover, the effect of 50% substitution of NaCl by KCl in the brines was examined to produce a reduced-sodium product with multifunctional potential. For this purpose, Lactiplantibacillus pentosus B363 and Lactiplantibacillus plantarum B380, previously isolated from table olive fermentations and characterised for technological and probiotic potential, were inoculated at the onset of fermentation in 6% (w/v) NaCl and 3% (w/v) NaCl/3% (w/v) KCl salt brines. The microbial populations (LAB, yeasts, and Enterobacteriaceae), pH, acidity, salt content, organic acids, and ethanol were measured in the brine for 146 days. Additionally, the recovery of each starter culture from the olive drupes at the beginning (5 days) and final (146 days) stages of fermentation was determined by plating, genotyping, and identification through RAPD-PCR and 16S region amplicon sequencing, respectively, and subsequent strain differentiation through rep-GTG5 fingerprint analysis. The results revealed the dominance of LAB in populations from 5.5 to 8.1 log CFU/mL. The final recovery rate of L. pentosus B363 on the olives was approximately 80% in both 6% (w/v) NaCl and reduced (3% (w/v) NaCl/3% (w/v) KCl) salt brines. Similarly, L. plantarum B380 recovery rates were 89% and 85%, respectively, for the same fermentations. Yeasts coexisted with LAB in counts ranging from 2.3 to 5.8 log CFU/mL, whereas no enterobacteria were enumerated in the brines and olives at the end of fermentation. The obtained fermentation profile and the sensory analysis of the olives revealed a typical lactic acid fermentation in both control and reduced-sodium brines. The current results support the feasibility of the production of reduced-sodium natural black olives with probiotic potential. The proposed fermentation process, including the selected starters, can be readily employed by the table olive industry to meet consumers' needs for low-sodium dietary intake while enhancing the functional potential of table olives. Natural black olives were fermented with LAB starter cultures in reduced-sodium brine. The selected LAB cultures were L. pentosus and L. plantarum with probiotic potential. Results revealed dominance of LAB followed by yeasts and absence of enterobacteria. The recovery rate of L. pentosus was 80% in control and reduced-sodium brines. The recovery rates of L. plantarum were 89% and 85% in control and reduced-sodium brines. Salt reduction was not perceived by the taste panel and olives were acceptable. The profile of fermentations indicated typical lactic acid fermentation in both salt brines. image