Lactobacillus casei cells were immobilized on fruit (apple and pear) pieces and the immobilized biocatalysts were used separately as adjuncts in probiotic cheese making. In parallel, cheese with free L. casei cells and cheese only from renneted milk were prepared. The produced cheeses were ripened at 4 to 6 degrees C and the effect of salting and ripening time on lactose, lactic acid, ethanol concentration, pH, and lactic acid bacteria viable counts were investigated. Fat, protein, and moisture contents were in the range of usual levels of commercial cheeses. Reactivation in whey of L. casei cells immobilized on fruit pieces after 7 mo of ripening showed a higher rate of pH decrease and lower final pH value compared with reactivation of samples withdrawn from the remaining mass of the cheese without fruit pieces, from cheese with free L. casei, and rennet cheese. Preliminary sensory evaluation revealed the fruity taste of the cheeses containing immobilized L. casei cells on fruit pieces. Commercial Feta cheese was characterized by a more sour taste, whereas no significant differences concerning cheese flavor were reported by the panel between cheese containing free L. casei and rennet cheese. Salted cheeses scored similar values to commercial Feta cheese, whereas unsalted cheese scores were significantly lower, but still acceptable to the sensory panelists.

In the present study, cheese whey was utilized for the development of a novel functional beverage, using Lactobacillus casei ATCC 393 probiotic cells immobilized on Pistacia terebinthus resin (pissa Paphos). Evaluation of shelf life of the produced beverages showed that spoilage microorganisms were not observed in beverages containing P. terebinthus resin. Terpenes’ rich content might have contributed to the antimicrobial activity of the produced beverages; however, no significant effect on the viability of the immobilized probiotic cells was obtained. Whey beverages containing the immobilized biocatalyst retained a high viability (>1 × 10⁶ CFU/g) of probiotic cells during a storage period of 30 days at 4 °C. The superiority of whey beverages containing the immobilized biocatalyst was also highlighted by GC-MS analysis, while the enhanced aromatic profile, which was mostly attributed to the higher concentration of terpenes, was also detected during the sensory evaluation performed. Conclusively, this study indicated the high commercialization potential of these novel functional whey beverages, within the frame of a sustainable dairy waste valorization approach. To the best of our knowledge, this is the first food-oriented approach within the guidelines of the circular economy reported in the literature, using the autochthonous Pistacia terebinthus resin for the production of functional whey beverages.

In the present study, a novel potentially probiotic Lactobacillus paracasei strain, previously isolated from dairy products, was evaluated as a starter culture of Feta-type cheese production. Targeting industrial applications, the starter culture was applied as a ready-to-use freeze-dried culture that was either free or immobilized. The immobilized biocatalyst composed of Lactobacillus paracasei K5 cells absorbed within delignified wheat bran prebiotic carrier. All produced cheeses were compared with cheese manufactured by renin enzyme. Several parameters that affect acceptability, quality and shelf-life of Feta-type cheese were investigated, including microbial populations, physicochemical characteristics and cheese volatiles through 90 days of ripening and storage. Survival of L. paracasei K5 remained in high levels (≥6.0 log cfu/g) after the 90th day of cheese production, as recorded by combining microbiological enumeration and strain-specific multiplex PCR analysis. The use of the freeze-dried novel starter culture (free or immobilized) enhanced the aromatic profile of Feta-type cheeses. Finally, the use of the potentially synbiotic immobilized biocatalyst further improved aromatic characteristics of produced cheese and decrease of possible spoilage or pathogenic microorganisms. These findings indicate the potential industrial use of freeze-dried L. paracasei K5 as starter culture for the production of good-quality functional Feta-type cheese.