Approaches to improve the growth of the starter lactic acid bacterium OM13 during the early stages of green Spanish-style table olive production

Abstract

The present research aimed at determining the optimal conditions for the lactic acid fermentation of green Spanish-style table olives. The work is a follow-up, and focuses on the performance of the commercial starter strain Lactobacillus pentosus OM13 by applying an acclimatization step and the addition of nutrients, and concentrations of lactic acid that were previously investigated. The acclimatization of the cells warranted the dominance of the starter culture even at an inoculation level of 2 Log cycles lower than that commonly used in standard fermentation. A significant effect was found in terms of acidification kinetics within the first week of fermentation, with the highest decrease in pH, at ~2.5 units, which occurred in the trial and after inoculation with 106 CFU/mL of starter after acclimatation (EO3) that showed values similar to control C obtained with Lactobacillus pentosus OM13 at a concentration of 107 CFU/mL. After day 3, further decreases in pH of up to 4.30 were observed until day 30, and then these values remained almost constant until the end of process (day 190) when lower pH values were reached for trial EO3 and control C. The results of microbiological dynamics, the changes in VOCs and finally the effect of the processes on the sensory analysis of the fermented product were investigated by multivariate analysis. The acclimatization process and the initial inoculation level influenced the bacterial microflora, aromatic compounds and organoleptic characteristics of the final product. Finally, the trials C, EO2 and EO3 showed higher values (60-80%) of preferences and satisfaction compared to other experimental productions.

Effect of Glucose and Inactivated Yeast Additions on the Fermentation Performances of Lactiplantibacillus pentosus OM13 during the Production of Nocellara del Belice Table Olives

“…The higher counts, varying between 0.2 and 1.2 log cycles, clearly demonstrate the importance of using these adjuvants to improve the fermentation performance of the starter strain OM13. LAB dynamics showed a slightly different trend, probably due to the absence of adjustment of the initial brine pH with lactic acid [5]; a similar trend was reported by Alfonzo et al [9]. The practice of acidification of brine through the addition of lactic acid or hydrochloric acid is used to improve the survival and dominance of the inoculated starter strain [5,25].…”

“…In this case, the use of a nutrient, activator, and acclimatisation period positively influenced LAB population levels, especially in the first 15 d of fermentation. LAB dynamics were comparable to those of table olive production with artificially acidified brine [9,26].…”

“…However, starter strain activities can be strongly limited by a non-optimal initial brine pH (due to the presence of soda residues), insufficient nutrients, and inadequate fermentation temperature [8]. The value of brine pH can be easily adjusted with lactic acid [9,10]. Temperature is a process parameter difficult to control during fermentation because of the high volume of the fermentation tanks and the elevated energy required.…”

“…The rapid growth of LAB determines fast acidification of the brine, creating a hostile environment for alternative and/or pathogenic microorganisms [7]. Different innovative protocols involving the use of the "pied de cuve" technique, starter strain acclimatisation, and the use of adjuvants have recently been successfully proposed to optimise the rapid increase of LAB cell densities in the early phase of fermentation [9,12]. Although the results obtained were highly valid, it was considered essential to further improve the production protocol in the inoculation phase of the starter strain L. pentosus OM13 by using new nutrient and fermentation activator formulations.…”

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

“…Among LAB species, Lactiplantibacillus pentosus and Lactiplantibacillus plantarum have been extensively used in inoculated fermentations and investigated for their technological and probiotic potential (Heperkan, 2013;Bonatsou et al, 2017;Martorana et al, 2017;Argyri et al, 2020). Moreover, recent reports indicate that the fermentation performance of starter cultures can be further enhanced by adding specific nutrients to the brines at the beginning of fermentation, to facilitate the rapid acidification of the brine and maintain low pH values that could control the growth of undesirable microorganisms and hence minimise the risk of spoilage (Alfonzo et al, 2018(Alfonzo et al, , 2023. Taking into account the expanding market for functional foods, new perspectives have arisen for the use of table olives as a vehicle of probiotic microorganisms to consumers.…”