Autochthonous and Probiotic Lactic Acid Bacteria Employed for Production of "Advanced Traditional Cheeses"

Abstract

Microbial characterization of two Italian traditional cheeses, Giuncata and Caciotta Leccese, was carried out, with the aim to isolate autochthonous bacterial strains to be used as starters to improve and standardize the quality of these cheeses. More than 400 bacterial isolates were found, using PCR-based identification, to belong to 12 species of the Streptococcus, Lactococcus, Lactobacillus, and Leuconostoc genera. The dominant strains were screened for antagonistic activity against pathogenic and spoilage bacteria and exopolysaccharide production, acidification, and proteolytic activity. Since Streptococcus macedonicus was found to be the most prevalent lactic acid bacteria species present in milk and in both types of cheese, the best performing strain of this species was successfully used, alone or in combination with a selected autochthonous Lactococcus lactis strain, in pilot-scale productions of Giuncata and Caciotta Leccese cheeses, respectively. The combined inoculums of selected autochthonous strains positively influenced the sensory characteristics of both Giuncata and Caciotta cheeses. Finally, the selected autochthonous cultures were enriched with a potentially probiotic Lactobacillus rhamnosus strain and successfully used in pilot-scale productions of these traditional cheeses. To the best of our knowledge, this is the first study reporting the use of an autochthonous S. macedonicus strain as a starter for the production of cheeses with added probiotics. In addition, the identification of the probiotic strain in the feces of healthy volunteers fed with the advanced traditional cheese proved its effectiveness as a carrier for the delivery of probiotics to the human body.

Keywords: Lactobacillus rhamnosus; Lactococcus lactis; Streptococcus macedonicus; autochthonous starter cultures; cow milk; fresh cheese; goat milk; microbial food quality and safety; probiotic cheese; ripened cheese.

Figure 1

Distribution of microbial populations at different steps of traditional production of Caciotta Leccese.

Figure 2

Distribution of microbial populations at different steps of traditional production of Giuncata Leccese, and during its storage at 10 °C for 20 days.

Figure 3

Distribution of endogenous species in Caciotta Leccese after 60 days of ripening.

Figure 4

Values of pasteurized milk acidification of selected autochthonous lactic acid bacteria tested.

Figure 5

Proteolytic activity of some of the autochthonous lactic acid bacteria tested. Orange bars represent significantly higher proteolytic activity values.

Figure 6

Population dynamics of S. macedonicus and Lactobacillus rhamnosus at different steps of the production and cold storage of uninoculated and inoculated advanced Giuncata Leccese samples.

Figure 7

Population dynamics of S. macedonicus, Lactococcus spp. ASC4, and Lb. rhamnosus at different steps of production of the inoculated Caciotta.

Figure 8

Lb. rhamnosus LR04 counts from the feces of three healthy volunteers (different colors) fed with Caciotta cheese containing the probiotic identified by species-specific and RAPD-PCR.