Effects of ripening time and combination of ovine and caprine milks on proteolysis of Picante cheese

Abstract

Proteolysis in Picante cheese was characterized by assaying for breakdown products throughout a 180 day ripening period using different combinations of ewe's and goat's milks. Parameters analysed were total nitrogen (TN), water-soluble nitrogen (WSN) and non-protein nitrogen (NPN) using Kjeldahl and spectrophotometric methods, and casein profile by electrophoresis. WSN at 180 days of ripening was 2529% TN. The maximum NPN values were attained by 180 days of ripening and corresponded to 87% and 92% of the WSN in OC and lOOC, respectively (where iC denotes a cheese manufactured with i% caprine milk). Statistically significant correlations were obtained between the various analytical methods of assay for nitrogen and ripening time. The spectrophotometric methods using either trinitrobenzenesulphonic acid or cadmium-ninhydrin proved satisfactory in assessing the ripening index (instead of the Kjeldahl method). Degradation of /J-caseins at 180 days was 18. 8,26.4,40.2, 55.6 and 36.5% for OC, 25C, 5OC, 75C and 1 OOC, respectively. Degradation of cw,-caseins by 180 days was 35.9,40.2, 81.8,93.0 and 68.7% for OC, 25C, 5OC, 75C and lOOC, respectively. In general, a higher cheesemaking milk fraction of caprine milk was associated with higher amounts of y-caseins. 0 1997

Influence of starter cultures on the proteolysis of Teleme cheese made from different types of milk

“…Also, the rate of hydrolysis of β-CN is slower than that of α s -CNs in all cheeses, regardless of the kind of milk and culture used. This is in agreement with the results found for other cheeses from sheep's, goat's or cow's milk [ 8,27] and it might be explained by the low pH (4.26-4.38) during ripening and storage of Teleme cheeses that does not favor the hydrolysis of β-CN by plasmin. Moreover, the high NaCl content of white-brined cheeses results in retarding β-CN hydrolysis [7].…”

Lipolysis in Picante cheese: Influence of milk type and ripening time on free fatty acid profile

“…Figure 1 shows that the effect of cheese milk composition on lipolysis in Picante chee se is not significant; however, higher proportions of caprine milk in the cheese milk were in general associated with higher total concentration ofFFA, especially after 25 days of ripening, although chee ses manufactured with 75% of goat's milk exhibited the highest values by 180 days. These observations are probably a conse- quence of the fact that cheeses richer in goat's milk contain higher levels of fat [7], a somewhat unexpected observation since ewe's milk is often considered to possess higher fat content than goal' s milk. In our case, such rule can also be applied: the fat contents of milk from Chamequeira goat (4.5-6.5 %) were essentially below those of milk from Frizia ewes (5.5-8.0 %), and so differences in the protein matrix of the cheese, or in the whey expression pattern during manufacture, might account for the aforementioned unexpected result.…”

“…At the time of milk collection (February), females were undergoing a feeding regime that consisted mainly of natural grass pasture and oats, and had given birth to calves 13 weeks before (on average). For each batch, 90 L of milk were used to manufacture 20 cheeses according to traditional procedures [7]. Cheeses from each batch were taken at random and sent under refrigerated conditions to our laboratory for analysis after 0,9,25,40, 55,83, llO, 140, and 180 days of ripening (counted from the time at which the first salting procedure was complete).…”

“…Sorne recent work has appeared in the literature concerning Picante chee se characterization, which has encompassed microbiological studies [5,6] and physicochemical and proteolysis studies [7]. This paper attempts to complement such studies by tackling the lipolysis in Picante chee se during ripening and ascertaining the effect of using different proportions of ewe's and goat's milks for its manufacture.…”

Influence of l-cysteine, oxygen and relative humidity upon survival throughout storage of probiotic bacteria in whey protein-based microcapsules

“…Two-way ANOVA was also applied to yield data presented in Table 1. ANOVA is valid provided that the experimental errors are independently and normally distributed, and possess a constant variance, hence, the original data had to be transformed via l-power forms, so as to achieve normality (Box, Hunter, & Hunter, 1978;Freitas & Malcata, 1996;Freitas, Sousa, & Malcata, 1995). The Holm-Sidak method was finally used for pairwise comparisons, also at the P ¼ 0.05 level of significance.…”