Raw MilkThe SCC of raw milk was det

Raw Milk
The SCC of raw milk was determined by flow cytometry with a Bentley Somacount 500 instrument (Bentley Instruments Inc., Chaska, MN); antibiotic residue by Delvotest kit (DSM Food Specialties Dairy Ingredients, Delft, the Netherlands); pH (Digimed model DM-20, Digicron Analítica Ltda, São Paulo, Brazil) by introducing the electrode directly into the sample (25°C); total solids (AOAC, 1995; method 925.23; 33.2.09/A); fat by Gerber method (British Standards Institution, 1989); ash (AOAC, 1995; method 935.42; 33.2.10); and lactose by difference between total solids and other milk solids. Total nitrogen (TN; AOAC, 1995; method 991.20; 33.2.11), pH 4.6 soluble nitrogen (pH 4.6-SN; AOAC, 1995; method 998.05; 33.2.64) and 12% TCA-soluble nitrogen (12% TCA-SN; AOAC, 1995; method 991.21; 33.2.12) were determined by the Kjeldahl method. Protein was estimated by using a conversion factor of 6.38. True protein (TP) and casein content were calculated as follows: TP = (TN – 12% TCA-SN) × 6.38, and CN content = (TN – pH 4.6-SN) × 6.38, respectively. The casein content as a percentage of true protein (CN/TP) was considered as a proteolysis index for raw milk