14A-50 |
Cheese making properties of high pressure processed milk: Pressure and holding time effects |
J. J. RODRÍGUEZ1, S. Clark2, B. G. Swanson2, and G. V. Barbosa-Cánovas1. (1) Dept. of Biological Systems Engineering, Washington State Univ., 213 L.J. Smith Hall, PO Box 646120, Pullman, WA 99164-6120, (2) Dept. of Food Science & Human Nutrition, Washington State Univ., 226 FSHN Bldg., PO Box 646376, Pullman, WA 99164-6376 Processing milk by high hydrostatic pressure improves properties such as rennet coagulation time (RCT), gel firmness, and cheese yield. The selection of pressure and holding time is relevant to control the extent of casein micelle disruption and whey protein denaturation, which ultimately determines the milk cheese-making properties and cheese characteristics. The objective of this work was to evaluate the cheese-making properties of pressure treated milk at selected pressures and holding times. Standardized (fat/protein=1.2) raw milk was subjected to 0, 300 and 600 MPa for 0, 5 and 15 min. Rennet coagulation was evaluated by oscillatory testing at 0.5 ¦ÌNm and 1Hz. The RCT was defined as the time required to reach a storage modulus (G') of 1 Pa. The G' value after 40 min was used to estimate gel firmness. The precipitate of samples with G'=10 Pa, centrifuged at 15 000g for 15 min at 5oC, was used for estimating cheese yield. Total nitrogen and SDS-PAGE electrophoresis of the supernatant were utilized to evaluate whey proteins incorporation into the cheese matrix. Cheese yield increased as pressure increased in all treatments but 600 MPa for 15 min where coagulation was inhibited. Pressurizing the milk at 300 MPa or 600 MPa for 0 min, significantly (p °Ü 0.05) reduced the RCT by ~8 min, promoted a five fold increase in firmness, and incorporate little whey protein into the curd. Milk treated at 600 MPa for 5 min showed the highest increase in yield (7.3%), longest RCT (32 min), and gel firmness similar to curds obtained from raw milk. The above results indicate that high hydrostatic pressure can be potentially used to develop cheeses and other dairy products with novel and target physicochemical characteristics and increased yield.
Session 14A, Dairy Foods: General developments in dairy technology I
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