Effect of Immobilized Pediococcus acidilactici ORE5 Cells on Pistachio Nuts on the Functional Regulation of the Novel Katiki Domokou-Type Cheese Microbiome

Nowadays, functional foods supplemented with health-promoting microorganisms have attracted consumer attention due to their health benefits. However, maintaining high cell loads, which consist of an essential requirement for conferring the health effect, is a real bottleneck for the food industry due to viability declines during food processing and storage. Hence, freeze-drying and cell immobilization have been suggested to enhance cell viability. The aim of our study was to assess the effect of freeze-dried immobilized P. acidilactici ORE5 on pistachio nuts on the functional regulation of the Katiki Domokou-type cheese microbiome. Supplementation of Katiki Domokou-type cheese with free or immobilized P. acidilactici ORE5 culture resulted in cell loads > 8.5 logcfu/g up to 7 days of storage. Both free and immobilized P. acidilactici ORE5 cells suppressed the growth of L. monocytogenes after deliberate inoculation, acting as a protecting shield. HS-SPME GC/MS analysis showed that the incorporation of P. acidilactici ORE5 culture in cheese resulted in an improved volatile compounds profile, as verified by the preliminary sensory evaluation. According to Next-Generation Sequencing analysis, a wide range of bacterial diversity was revealed among samples. The most abundant genus was Lactococcus in all samples, while the results showed an increased presence of Pediococcus spp. in cheese fortified with P. acidilactici ORE5 culture, highlighting the ability of the strain to survive in the final product. Furthermore, the incorporation of P. acidilactici ORE5 culture in cheese had a significant impact on cheese microbiome composition, as the presence of spoilage bacteria, such as Chryseobacterium, Acinetobacter and Pseudomonas, was significantly less compared to the control cheese, indicating quality improvement and prolongation of the product’s shelf-life.