Abstract
Non-starter adventitious lactobacilli grow in cheese, reaching elevated numbers during late ripening. The interest may concern the use of non-starter lactobacilli as an adjunct in the form of fresh or attenuated cells. The use of adjunct starters may have several repercussions for flavour and acceleration of the maturation, depending on microbial species/strains and/or the cheese varieties. Caciotta is a traditional cows' milk cheese manufactured in Italy. Usually, ripening of this variety is not extended to more than three months. This work aimed to study the effect of selected non-starter lactobacilli adjuncts, in the form of fresh or attenuated cells, on the ripening of caciotta cheese. In a preliminary study, 60 strains of mesophilic lactic acid bacteria were screened based on the following enzyme activities: aminopeptidase type N, proline iminopeptidase, endopeptidase, glutamate dehydrogenase, and cystathionine lyase. Lactobacillus casei LC01, Lactobacillus curvatus 2770 and Lactobacillus paracasei FC25 were selected and used as adjuncts, in form of fresh or attenuated cells for making caciotta cheese at an industrial plant. The control cheese was manufactured under the same conditions, except for the adjunct. Cheeses were analysed during the ripening (60 days) for chemical and microbiological composition. Random Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) analysis was used to monitor the population of non-starter lactobacilli during caciotta cheese ripening. Proteolysis was evaluated by the determination of total and individual concentration of free amino acids and by urea-PAGE and RP-FPLC analyses of water-soluble and insoluble fractions. Enzyme activities were determined in the water extract of the cheeses.