Effects of Proteolytic and Lipolytic Enzyme Supplementations on Lipolysis and Proteolysis Characteristics of White Cheeses

Effects of proteolytic (Neutrase, Bacillus subtilis-originate, 0.20 (P1) and 0.40 g 100 L-¹ (P2)) and lipolytic (Piccantase A, Mucor miehei-originated, 0.05 (L1) and 0.10 g 100 L-¹ (L2)) enzyme supplementations to cheese milk on lipolysis and proteolysis characteristics of 90-day ripened cheese samples were investigated in this study. While enzyme supplementation did not have significant effects on titratable acidity, fat and protease-peptone nitrogen ratios of cheese samples, dry matter, salt, protein, water soluble nitrogen, 12% trichloroacetic acid soluble nitrogen ratio (TCA-SN), 5% phosphotungstic acid soluble nitrogen (PTA-SN), casein nitrogen ratios, penetrometer value, total free fatty acids (TFFA) and total free amino acids (TFAA) were significantly influenced by enzyme supplementations. Individual free amino acids (15 of them) were also determined. Free amino acid contents of enzyme-supplemented cheeses were higher than the control cheese and the values increased in all cheese samples with the progress of ripening (p < 0.05). The highest amino acids in all periods of ripening were identified as glutamic acid, lysine, proline and aspartic acid. The major (Ca, P, Na, K, Mg) and minor (Zn, Fe, Cu, Mn) mineral levels of cheeses decreased with the progress of ripening and the effects of enzyme supplementations on these attributes (except for magnesium and manganese) were found to be significant (p < 0.01). As to conclude, enzyme supplementations increased proteolysis and lipolysis and accelerated ripening and thus reduced ripening durations. Especially the enzyme ratios in P1 and L1 cheeses were found to be suitable for reducing the ripening period in White cheese without any adverse effects.

Role of Microbial Cultures and Enzymes During Cheese Production and Ripening

Many different kinds of cultures, enzymes, and methods are used during the production and ripening of a variety of cheese types. In this chapter, the importance, types, and applications of microbial cultures during cheese production are discussed. Moreover, an overview of the important role of enzymatic systems, either derived from these cultures or directly added to the milk fermentation, is presented. The main biochemical events including glycolysis, lipolysis, and proteolysis during cheese ripening are explained, focusing on their end products, which contribute to the development of the overall aroma of cheese.

Tryptophan catabolism in Brevibacterium linens as a potential cheese flavor adjunct

Attempts to develop a desirable reduced fat Cheddar cheese are impeded by a propensity for flavor defects such as meaty-brothy, putrid, fecal, and unclean off-flavors in these products. Recent studies suggest aromatic amino acid catabolism of starter, adjunct, and nonstarter lactic acid bacteria significantly impact off-flavor development. The objective of this study was to delineate pathways for catabolism of tryptophan (Trp) in Brevibacterium linens, a cheese flavor adjunct, and to determine the potential for this organism to contribute to this defect. Growth and production of aromatic compounds from Trp by B. linens BL2 were compared in two incubated conditions (laboratory and a cheese-like environment). A chemically defined medium was used to determine the cellular enzymes and metabolites involved in Trp catabolism. Trp was converted to kynurenine, anthranilic acid, and three unknown compounds in laboratory conditions. The accumulation of other unknown compounds in the culture supernatant in laboratory conditions indicated that B. linens BL2 degraded Trp by various routes. Up to 65% of Trp was converted to anthranilic acid via the anthranilic acid pathway. To assess this potential before cheese making, the cells were incubated in cheese-like conditions (15 degrees C, pH 5.2, no sugar source, 4% NaCl). Trp was not utilized by BL2 incubated in this condition. Enzyme studies using cell-free extracts of cells incubated in laboratory conditions and assayed at optimal and nonoptimal enzyme assay conditions revealed Trp transaminase (EC 2.6.1.27) was active before enzymes of the anthranilic acid pathway were detected. The products of Trp transaminase activity were not, however, found in the culture supernatant, indicating these intermediates were not exported nor accumulated by the cells. Enzymes assayed in nonoptimal conditions had considerably lower enzyme activities than found in laboratory incubation conditions. Based on these results, we hypothesize that these enzymes are not likely to be involved in the formation of compounds associated with off-flavors in Cheddar cheese.

Aspects of enzymology and biochemical properties of Brevibacterium linens relevant to cheese ripening: a review

Brevibacterium linens is a major surface microorganism that is present in the smear of surface-ripened cheeses. The enzymology and biochemical characteristics of B. linens influence the ripening and final characteristics of smear surface-ripened cheeses. Proteolytic, peptidolytic, esterolytic, and lipolytic activities, which are of particular importance in the ripening process, are discussed in detail. This review also describes the production of volatile compounds, especially sulfur-containing ones, by B. linens, which are thought to be important in respect to the flavor of smear surface-ripened cheeses. The unique orange-colored carotenoids and the factors effecting their production by B. linens are also presented. The catabolism of aromatic amino acids, bacteriocin production, plasmids, and miscellaneous biochemical and physiological properties (peptidoglycan type, antibiotic resistance, insecticide degradation, and biotechnological applications) of B. linens are discussed. The problem associated with the current taxonomical classification of B. linens strains caused by strain variation is evaluated. Finally, the application of B. linens cell extracts or its proteolytic enzymes as cheese ripening accelerants for semi-hard or hard cheese varieties is considered.