Effect of Somatic Cell Count on Prato Cheese Composition

Abstract

The objective of this research was to evaluate the effect of 2 levels of somatic cell counts (SCC) in raw milk on Prato cheese composition, protein and fat recovery, cheese yield, and ripening. A 2 x 6 factorial design with 3 replications was performed in this study: 2 levels of SCC and 6 levels of storage time. Initially, 2 groups of dairy cows were selected to obtain low (<200,000 cells/ mL) and high (>600,000 cells/mL) SCC in milks that were used to manufacture 2 vats of cheese: 1) low SCC and 2) high SCC. Milk, whey, and cheese compositions were evaluated; clotting time was measured; and cheese yield, protein recovery, and fat recovery were calculated. The cheeses were evaluated after 5, 12, 19, 26, 33, and 40 d of ripening according to pH, moisture, pH 4.6 soluble nitrogen, 12% trichloroacetic acid soluble nitrogen as a percentage of total nitrogen, and firmness. High-SCC milk presented significantly higher total protein and nonprotein nitrogen and lower true protein and casein concentrations than did low-SCC milk, indicating an increased whey protein content and a higher level of proteolysis. Although the pH of the milk was not affected by the somatic cell level, the cheese obtained from high-SCC milk presented significantly higher pH values during manufacture and a higher clotting time. No significant differences in cheese yield and protein recovery were observed for these levels of milk somatic cells. The cheese from high-SCC milk was higher in moisture and had a higher level of proteolysis during ripening, which could compromise the typical sensory quality of the product.

Qualidade de queijo minas frescal preparado com leite com diferentes quantidades de células somáticas

“…Thus, a higher loss of solids is expected to occur in whey from the pressed curd, used in cheddar cheese manufacturing, when compared with the nonpressed, high moisture minas frescal cheese. The results of the present study are consistent with those reported by Mazal et al (2007), who did not observe any significant difference in the yield of the semi-hard prato cheese manufactured from milk containing SCC at levels from 200,000 to 600,000 cells mL -1 .…”

“…In the present study, the failure of SCC in milk to affect the proteolysis of minas frescal cheese is in disagreement with previous reports that indicated that proteolysis was increased in cheddar cheese manufactured from milk with 500,000 cells mL -1 (Rogers & Mitchell, 1994), and in prato cheese made from milk with more than 600,000 cells mL -1 (Mazal et al, 2007). In fact, minas frescal is a nonripened cheese that is marketed for consumption immediately after manufacture.…”

“…Mazal et al (2007) did not also observe any significant effect of SCC on the firmness of prato cheese. However, in the present work, there was an interaction effect between SCC and time of storage (p<0.05).…”

“…Although such effects are presumably expected to occur during manufacture of any type of cheese, very little information is available on the possible influence of high SCC in milk on the quality of other cheeses. Mazal et al (2007) observed that prato cheese, a traditional Brazilian cheese, had high proteolysis and high moisture content when produced from milk with SCC greater than 600,000 cells mL -1 , although no effect was found on the cheese yield and protein recovery.…”

Buffalo milk composition, processing factors, whey constituents recovery and yield in manufacturing Mozzarella cheese

“…and the final quality of the product (taste, softness, melting, shelf life, etc.). Furthermore, the increase in processing time results in higher production costs for the industry and reduced profits (Mazal et al, 2007).…”