Twenty-seven Lactobacillus pentosus strains, and the undefined starter for table olives from which they were isolated, were characterised for their technological properties: tolerance to low temperature, high salt concentration, alkaline pH, and olive leaf extract; acidifying ability; oleuropein degradation; hydrogen peroxide and lactic acid production. Two strains with appropriate technological properties were selected. Then, table olive fermentation in vats, with the original starter, the selected strains, and without starter (spontaneous fermentation) were compared. Starters affected some texture profile parameters. The undefined culture resulted in the most effective Enterobacteriaceae reduction, acidification and olive debittering, while the selected strains batch showed the lowest antioxidant activity. Our results show that the best candidate strains cannot guarantee better fermentation performance than the undefined biodiverse mix from which they originate.

Preservation of cheese microbiota biodiversity is central to the sensory quality of traditional and PDO cheeses. Lyophilized commercial selected starters, being advantageous in terms of cells concentration, are supplanting natural cultures causing important loss of microbial biodiversity in the dairy environment. Biodiversity could be recovered using natural starter cultures, however their cells concentration after propagation is lower than the commercial ones. Two autochthonous and biodiverse starter cultures (MixA and MixB) coming from scotta (residual whey from Ricotta cheese manufacture), collected in the 1960 s from Pecorino Romano PDO cheese manufactures, were revitalized in reconstituted commercial powder scotta. The aim of this study was the propagation of the microbial starter mixes increasing their bacterial concentration in the pellet, reducing nonessential scotta components by a fast and not-expensive method, without changing the microbial community balance. The behaviour of each mix inoculated in scotta was compared to that in half-concentrated, clarified, and half-concentrated-clarified scotta. Higher cells concentration in the pellets from the modified scotta was obtained, without changing technological performances and microbial fingerprint. The pellets obtained were reinoculated in commercial scotta for the preparation of the scotta-innesto (the typical starter for Pecorino Romano), and no differences were observed among the treatments after incubation. The reduction of nonessential scotta's components could help the reproduction of natural starter cultures preserving their properties.

During Pecorino Romano PDO cheese production, scotta (residual whey from ricotta cheese manufacturing) or siero (whey) can be integrated with autochthonous starters, natural and composed of an indefinite number of species and strains, or commercial selected starters to obtain scotta/siero-innesto. In this study, three biodiverse autochthonous natural starter cultures (SR30, SR56, and SR63) belonging to the Agris Sardegna BNSS microbial collection, composed of different strains belonging to the species Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Enterococcus faecium, and Limosilactobacillus reuteri were lyophilized and combined into two starter mixes (A and B). The scotta/siero-innesto and the Pecorino Romano obtained using natural starters were compared with those obtained using commercial selected starters during three seasons of the cheesemaking campaign. Different pH and microbial compositions for the scotta/siero-innesto obtained using natural or commercial starters were found, attributable to their different biodiversity. The six-month-ripened cheese microbiota was influenced mostly by the season of cheesemaking, whereas physico-chemical and sensory analyses did not highlight differences among the products obtained. In general, no effect attributable to the type of scotta/siero-innesto used was observed, allowing the conclusion that natural starter cultures can be used also in industrial-scale production, ensuring high stability in the technological performances and preserving the microbial, chemical, and sensory characteristics of Pecorino Romano PDO cheese.