Technological exploitation of PDO cheese as carrier of putative probiotics from plant origin

The development of functional foods with beneficial features is attracting the interest of the scientific community from many years . In this contest, the probiotic effect of milk-based products has been documented from the times of Metchnikoff, since they represent an optimal matrix of growth for beneficial lactic acid bacteria (LAB) or Bifidobacterium.Within this range of foods, cheeses are advantageous as a delivery system for viable probiotics over milk and fermented product such as yogurt, due to their higher pH, higher buffering capacity, solid consistency and higher fat content. So far, several kinds of long and medium ripening time cheeses were successfullysupplemented with probiotic from human origin, exploiting at the same time their beneficial and technological features. Vice versa, to our knowledge the addition of probiotic LAB from plant originin cheeses has not yet been investigated. Therefore, the aim of this work was to test putative probioticlactobacilli isolated from fermented olives as functional starter strains in the production of Toma piemontese PDO cheese evaluating the final presence of live probiotics after the simulated digestion process and the effects of the strains on the final product futures. Methods Trials were carried out in a local dairy company at industrial scale level, testing three putative probiotics: L. plantarum S11T3E, L. plantarum S2T10D and L. pentosus S3T60C (Botta et al., 2014).These adjunction cultures were added to the pasteurized milk prior to the cheese making, together with the commercial starter cultures, performing two independent experiments. The cheeses produced were sampled during the 120 days of ripening and at the end of this period the cheeses were subjected to an in vitro human digestion. Culture-dependent monitoring of the strains presence was performed from the production until the end of the simulated digestions: all lactobacilli recovered were identified by species-specific PCR and subsequently typed by means of Rep-PCR coupled with UPGMA cluster analysis. Furthermore, for each sample point the organic acid and sugar profiles of the cheeses was analyzed by using HPLC-UV-RI while the organoleptic features of the cheeses were assessed by a panel of untrained tasters. Results As far as the results are concerned, the cheeses supplemented with putative probiotics have shown an organoleptic profiles similar to those of the untreated controls, while different consumption of sugars and organic acids production were recorded among the three trials (P<0.05). The population of lactobacilli reached a concentration of 7.00 Log10 CFU g-1 at the 90th day of ripening period and then they has been stable until the end of the trial. The most part of the lactobacilli isolated from the functionalized cheeses were recognized as the putative probiotics, which therefore demonstrated a high adaptation capability to this food matrix. Concerning the simulation of digestion, we observed a low survival capability of the L. pentosus S3T60C compared to the other two strains (P<0.05). Discussion To conclude, the Toma piemontese PDO cheese has proven to be a suitable carrier for our putative probiotics, which did not modify significantly the organoleptic features of the product.