Correlation between protein profile and chemical composition, pH and texture parameters in cheese elaborated with three fat contents milk ripened at 28 days

Abstract

72 goat’s raw milk cheeses were elaborated according to the traditional hand-made cheese practices in Canary Islands (Spain), cheese were made with three different fat content milk: full-fat milk cheese (FFC, 5% fat in milk), reduced-fat milk cheese (RFC, 1.5% fat in milk) and low-fat milk cheese (LFC, 0.4% fat in milk). At 28 days of ripening, the gross composition, pH and texture profile analyze were analyzed and water-soluble proteins were extracted. Protein extract was separated on SDS-PAGE gel by duplicated. Person’s correlation analysis was performed between the electrophoretic bands values (intensity x area) and chemical composition (moisture, protein, fat and fat in dry matter), pH and texture profile analysis. alphas2-casein, peptides 2 and 3 showed significant correlations with all chemical parameters (moisture, protein, fat and fat in dry matter content), and the &alphas1-casein was correlated with pH and total protein percentage. Intensity x area value of alphas2-casein was positive correlated with moisture and total protein (0.60 and 0.64, respectively), and however showed negative correlation with cheese fat and fat on dry matter (-0.63 and -0.64), and it is according to the less rate of degradation of this casein. Also high correlations were found between peptides 2 and 3 and chemical parameters, those correlations were much higher with peptide 3. Positive correlation was observed between internal and external pH and alphas1-casein (0.58 and 0.53) and alphas2-casein (0.65 and 0.57) and negative with peptides 2 and 3. It’s known that as cheese fat content decrease, pH is higher and the casein rate of degradation is less. Fracturability, hardness, cohesiveness and gumminess correlated positively (0.65, 0.67, 0.62 and 0.62, respectively) as well adhesiveness and elasticity showed a negative correlation (-0.53 and -0.68, respectively) with alphas1-casein and alphas2-casein. Similar correlations were found between peptides 2 and 3 and the texture parameters studied, although the correlations were higher with peptide 3. In conclusion, the main correlation observed was that when pH increased, the percentage of casein increased too, and concomitantly, the proportion of peptides 2 and 3 decreased. At day 28 of ripening is possible to establish a stronger relationship between the electrophoretic bands profile on SDS-PAGE and texture parameters in goat cheese elaborated with raw milk.