Autochthonous starter effect on the microbiological, physicochemical and sensorial characteristics of Ibores goat's milk cheeses

Abstract

The effect of adding four Lactococcus lactis ssp. lactis autochthonous strains as single starters (A, B, C and D) on the microbiological, physicochemical and sensory characteristics of Ibores raw goat's milk cheese was investigated. Batches with a commercial starter (E) and with raw goat's milk without starter (F) were also made as controls. At the first day of ripening, the pH values of cheeses manufactured with any type of starter were significantly lower than those made without starter. There were significant differences (P < 0.05) in pH between batches, although no clear relationship with the starter type appeared. No significant differences (P < 0.05) in values of total solids (TS) or NaCl content were found between any of the batches after 7 d of ripening. The levels of the nitrogen fractions SN/TN and TCASN/TN were significantly (P < 0.05) higher in cheeses without starter after 7 and 30 d of ripening, but no significant differences were found between batches made with different starters. The evolution of lactic acid bacteria counts during ripening were very similar for all batches. While the enterococci counts in all types of cheeses throughout ripening remained practically constant, in cheeses manufactured with the commercial starter they were significantly (P < 0.05) lower at any given stage of ripening than those of the remaining types of cheeses. In cheeses made with autochthonous starters, the levels of coliforms and coagulase- positive staphylococci were reduced earlier in ripening than in the E and F cheeses. The best scores in the overall sensorial characteristics were awarded cheeses manufactured with two of the autochthonous starters, although the differences were not significant (P < 0.05) relative to cheeses made without starter. Goat milk cheese / autochthonous starter / ripening / sensorial quality