7 authors, including: Serena Niro Università degli Studi del Molise 25

Dairy Ingredients
After 2 days of storage no significant differences were observed for fermentative activities (data not shown). At 7 days of storage the content in L-lactic acid increased only in Ricotta samples added with Lb. paracasei subsp. paracasei F19 (RLB, RI+LB and RCF+LB). The highest increase in L-lactic acid was noted in RI+LB, underlining the suitability of free inulin as a substrate for the growth of the probiotic bacterium used in this research. In fact, in the samples from the batch RI+LB the content of fructans (inulin) decreased from 1.93 g 100 g^–1 to 1.56 g 100 g^–1, confirming the use of free inulin by the added microorganism. Moreover, this datum confirms previous results, which evidenced not only the ability of Lb. paracasei subsp. paracasei F19 to grow in presence of inulin, but also the preference of this prebiotic in respect to other more easily assimilable carbohydrates, such as lactose (10). On the other hand, during the storage period lactose decreased significantly (c.a. 10 %) only in the synbiotic sample RCF+LB, whereas the percentage of fructans resulted unchanged. Interestingly, the energy produced by the fermentative activity on carbohydrates, with the consequent production of lactic acid, was used by Lb. paracasei subsp. paracasei F19 for the response to stress conditions, such as low temperature and high solute concentration (37). In fact, in the experimental probiotic (RLB) and synbiotic (RI+LB and RCF+LB) samples, the load of Lb. paracasei subsp. paracasei F19, inoculated at 10⁹ cfu/serving size (100 g), remained constant during the entire storage period (Figure 2).

LAB resulted undetectable in Ricotta cheese used as

control (Figure 2), and undesirable microorganisms (Enterobacteriaceae, total and faecal coliforms, and Eumycetes) were undetectable in all the samples (data not shown).

The high survival of the probiotic strain during the cold storage represents an interesting result, since the beneficial effects of probiotics is strictly related to the daily size of viable cells ingested (38). Taking into account that dairy

probiotic products must provide not only the minimum number of cells to confer health effects, but also sensory acceptance by consumers, sensory attributes of the functional Ricotta cheese at 0 and 7 days of storage were investigated (Figure 3).

At the beginning of the storage (Figure 3a), Ricotta cheese produced with Lb. paracasei subsp. paracasei (RLB) and with inulin (RI and RI+LB) was particularly appreciated by judges for all the assayed descriptors, as highlighted by scores similar to those of the control (RC). On the contrary, the addition of chestnut flour lowered the perceived sensorial profile of Ricotta cheese for colour, taste pleasantness, consistence and homogeneity. After 7 days of storage (Figure 3b), the sensory profile of Ricotta cheese resulted substantially unchanged, except for a considerable decrease (P<0.05) for taste pleasantness in batch RI+LB due to an excessive acidification, as previously highlighted by chemical analyses (Table 2).