Effect of coagulant type and level on the properties of half-salt, half-fat Cheddar cheese made with or without adjunct starter: Improving texture and functionality

Production of soft unripened cheeses using acidic and salty coagulants: Investigation of technological and sensory characteristics

Soft cheeses are coagulated milk products obtained through acidification or applying a combination of acids and heat. In this research, in order to improve technological characteristics, the effects of different coagulants (salt and acids) and process parameters (temperature and homogenization pressure) on the organoleptic, textural, and functional characteristics of soft (unripened) cheese were investigated. The results revealed significant differences between cheeses coagulated with acid and mineral salt regarding protein recovery, fat content, and moisture content (p < .05). Acidic coagulants (74%-94%) resulted in higher cheese yield compared to mineral salt (66%-88%). Texture analysis indicated that the cheese produced with acetic acid had a firmer texture, while samples treated with citric acid exhibited better cohesiveness. Cheeses produced with minerals displayed more acceptable organoleptic characteristics regarding flavor, odor, and texture. This study offers valuable technological insights into cheese production with the highest yield and maximum acceptability.

Effect of Pseudomonas fluorescens proteases on the quality of Cheddar cheese

The objective of this study was to investigate the effect of adding different levels of a thermoresistant protease produced by a Pseudomonas fluorescens strain to milk on the manufacture and quality of Cheddar cheese. Fresh raw milk was collected, standardized, and pasteurized at 72°C for 15 s, and the enzyme was added to give a protease activity of 0.15 or 0.60 U/L (treatments P1 and P4, respectively), while one sample had no enzyme added (control). Milk was stored at 4°C for 48 h and Cheddar cheese was manufactured after 0 and 48 h of storage. Results indicated that the protease was active in milk during 48 h of storage; however, its effect on milk composition was minimal. The protein that was preferentially hydrolyzed by the protease over storage was β-casein, followed by κ-casein. The mean cheese yield and recovery of fat and protein obtained for all cheeses were not affected by protease activity. The protease showed low activity during cheese manufacture, possibly because of unfavorable conditions, including low pH. One of the factors that might have influenced protease activity was the pH of the curd (approximately 6.55 after acidification and 5.35 at milling), which was lower than that at which the enzyme would have optimum activity (pH 7 to 9). Consequently, the composition, pH, patterns of proteolysis, and hardness of all cheeses produced were similar and in accordance with values expected for that type of cheese, independently of the protease activity level. However, slight increases in proteolysis were observed in P4 cheeses and produced using milk stored for 48 h. Both the P1 and P4 cheeses had higher concentrations of free amino acids (FAA) compared with the control, whereas urea-PAGE electrophoretograms indicated a greater breakdown of caseins in the P4 cheese samples, which may be related to possible increases in numbers of proteolytic bacteria in milk during storage. Therefore, the thermoresistant psychrotrophic bacterial protease(s) tested in this study may affect the manufacture or quality of Cheddar cheese during ripening to a relatively limited extent. However, controlling initial levels of proteolytic bacteria in raw milk remains essential, because proteolysis affects the development of flavor and texture in cheese.

Effect of carbonation and probiotic addition on the physicochemical, microbiological and sensory characteristics of whey dairy beverage

This research communication addresses the impact of the addition of Lactobacillus casei and/or carbonation (CO2) on the chemical composition, physicochemical characteristics, probiotic survival, and sensory acceptance of passion-fruit flavored whey dairy beverages (70% milk/30% whey) during storage (30 d/4°C). The addition of Lactobacillus casei and/or carbonation did not impact on the chemical composition, pH values, and acceptance (flavor and overall impression) of the products, but increased the acidity, and decreased the aroma acceptance. The carbonation process did not affect the probiotic survival but decreased the acidity of the products during storage. It can be concluded that it is possible to develop a probiotic passion-fruit flavored carbonated whey dairy beverage with suitable chemical composition, acidity, sensory acceptance (>6 in 9-point hedonic scale) and probiotic viability (>7 log cfu/ml) that could be refrigerated stored for 30 d. This is the first report considering a probiotic non-fermented carbonated whey dairy beverage.

Composition, coagulation characteristics, and cheese making capacity of yak milk

Yak is one of the few species of which the rennet-coagulated cheese making characteristics of its milk are still not well understood. This study investigated composition and rennet-induced coagulation properties of milk from 17 individual yak cows in comparison with milk from 32 individual Holstein cows. Yak cows produced milk with generally higher concentrations of milk components. The concentrations of fat, protein, solids-not-fat (SNF), and calcium in yak milk were 1.89-, 1.68-, 1.46-, and 2-fold those in Holstein milk, respectively. The hydrodynamic radii of casein micelles (187.25 nm) and chymosin-induced paracasein (1,620 nm) were about twice the sizes of those found in Holstein milk. Higher concentrations of calcium in yak milk, together with larger sizes of casein micelles, explains the reason for its fast rate of curd formation and firmer curd texture. Optical microrheology analysis also showed that Ca²⁺ concentration had greater influence on the coagulation of yak milk than on Holstein milk. Cheese making trials with yak and Holstein milk proved the higher cheese yield of yak milk: 1.67-fold that of Holstein milk. Therefore, yak milk could be a suitable source of milk for enzyme-coagulated cheese making.