Traditional Bulgarian Dairy Products: Ethnic Foods with Health Benefits

The reported health effects of fermented dairy foods, which are traditionally manufactured in Bulgaria, are connected with their microbial biodiversity. The screening and development of probiotic starters for dairy products with unique properties are based exclusively on the isolation and characterization of lactic acid bacterial (LAB) strains. This study aims to systematically describe the LAB microbial content of artisanal products such as Bulgarian-type yoghurt, white brined cheese, kashkaval, koumiss, kefir, katak, and the Rhodope's brano mliako. The original technologies for their preparation preserve the valuable microbial content and improve their nutritional and probiotic qualities. This review emphasises the features of LAB starters and the autochthonous microflora, the biochemistry of dairy food production, and the approaches for achieving the fortification of the foods with prebiotics, bioactive peptides (ACE2-inhibitors, bacteriocins, cyclic peptides with antimicrobial activity), immunomodulatory exopolysaccharides, and other metabolites (indol-3-propionic acid, free amino acids, antioxidants, prebiotics) with reported beneficial effects on human health. The link between the microbial content of dairy foods and the healthy human microbiome is highlighted.

Effects of blends of camel and calf chymosin on proteolysis, residual coagulant activity, microstructure, and sensory characteristics of Beyaz peynir

Beyaz peynir, a white brined cheese, was manufactured using different blends of camel chymosin (100, 75, 50, 25, and 0%) with calf chymosin and ripened for 90 d. The purpose of this study was to determine the best mixture of coagulant for Beyaz peynir, in terms of proteolysis, texture, and melting characteristics. The cheeses were evaluated in terms of chemical composition, levels of proteolysis, total free amino acids, texture, meltability, residual coagulant activity, microstructure, and sensory properties during 90 d of ripening. Differences in the gross chemical composition were statistically significant for all types of cheeses. Levels of proteolysis were highly dependent on the blends of the coagulants. Higher proteolysis was observed in cheeses that used a higher ratio of calf chymosin. Differences in urea-PAGE and peptide profiles of each cheese were observed as well. Meltability values proportionally increased with the higher increasing levels of calf chymosin in the blend formula. These coagulants had a slight effect on the microstructure of cheeses. The cheese made with camel chymosin had a harder texture than calf chymosin cheese, and hardness values of all cheese samples decreased during ripening. The cheeses with a high ratio of calf chymosin had higher residual enzyme activity than those made with camel chymosin. No significant difference in sensory properties was observed among the cheeses. In conclusion, cheeses made with a high level of calf chymosin had a higher level of proteolysis, residual coagulant activity, and meltability. The cheeses also had a softer texture than cheeses made with a high content of camel chymosin. Camel chymosin may be used as a coagulant alone if low or limited levels of proteolysis are desired in cheese.

Growth Capacity of a Novel Potential Probiotic Lactobacillus paracasei K5 Strain Incorporated in Industrial White Brined Cheese as an Adjunct Culture

In this study, a novel potential probiotic strain Lactobacillus paracasei K5, previously isolated from traditional Greek Feta cheese and kefir grains, was evaluated as an adjunct culture for industrial white brined cheese production. Targeting industrial applications, apart from free cell cultures, a novel ready-to-use freeze-dried immobilized biocatalyst was prepared. The biocatalyst composed of L. paracasei K5 cells immobilized on delignified wheat bran prebiotic carrier and was freeze-dried without cryoprotectants. The adjunct free or immobilized culture was added separately without prior adaptation during white brined cheese manufacture and the produced cheeses were compared with commercial white brined cheeses. Several parameters that affect the acceptability and quality of the cheeses, including microbial populations, physicochemical parameters, volatile by-products and organoleptic characteristics, were analyzed through 70 days of storage. Results showed that the viability of the adjunct culture added either free or immobilized remained in high levels (7 to 8 log cfu/g) during maturation and storage. In addition, all white brined cheeses with the adjunct probiotic culture showed a sharp decrease in spoilage and pathogenic microorganisms such as enterobacteria, salmonella, staphylococci and coliforms during cheese maturation, especially when compared with the commercial white brined cheeses. Finally, after maturation time exceeded, all cheeses were characterized as safe for human consumption. Cheeses volatile compounds were significantly enhanced by the incorporated immobilized biocatalysts. These findings indicate the potential industrial use of freeze-dried ready-to-use immobilized lactobacilli as reinforcement adjunct cultures for the production of good-quality functional cheese products.

PRACTICAL APPLICATION

The launch on market of novel foods developed by the incorporation of functional ingredients provides potential benefits to consumers' diet and new business opportunities for producers. Probiotic food products are one significant category of functional foods. Thus, this study focused on the development of a novel ready-to-use freeze-dried potential probiotic biocatalyst for functional white brined cheese production. The potential industrial application of such biocatalysts is highlighted by their incorporation as adjunct cultures that resulted in good-quality functional cheeses.