Effects of homogenization pressure and selected additives on the physico-chemical properties of retort sterilized dairy beverages.

摘要

A beverage with 11% milk solids-nonfat, 3% milk fat, and 8% sucrose was made from skim milk, cream, nonfat dry milk, and sugar. In phase I, 6-carrageenan (6-CGN), 4-carrageenan (4-CGN), or locust bean gum (LBG) was added at 0 or 0.05%, and sodium citrate (SC), sodium tripolyphosphate (STPP), or sodium hexametaphosphate (SHMP) was added at 0 or 0.1%. The mixture was heated to 70°C, homogenized at 20, 50 and 90 MPa, canned, retort sterilized at 121°C for 6 minutes, and stored at 36°C. The effect of additives and homogenization pressure (HP) on the pH, particle size index (PI), creaming index (CI), and apparent viscosity (AV) was examined after 1, 10, 20, and 30 days storage. In phase II, the STPP at 0, 0.1, or 0.2%, and 4-CGN at 0, 0.05, or 0.1% was added to the basic formula. Processing was similar to phase I except that the pH was adjusted to 6.90 prior to the homogenization. The effect of STPP, 4-CGN, and HP on the pH, PI, CI, AV, soluble protein and minerals, and non-protein nitrogen (NPN) was determined.; 6-CGN with STPP produced the best PI and CI in phase I, and the AV was low when the HP was 90 MPa. LBG did not prevent creaming during storage and 4-CGN caused sedimentation of large particles. SHMP caused a greater decline in pH than STPP. Samples with HP of 50 or 90 MPa had better PI, CI and lower AV than those homogenized at 20 MPa.; A formula that contained 0.123% STPP and 0.025% 4-CGN in a beverage homogenized at 67.5 MPa produced a product with a PI and CI of 1.0 and an AV of 9.77 cPs in phase II. STPP at 0.2% level caused instability of proteins and caused sedimentation after sterilization. Samples that contained more than 0.05% 4-CGN and homogenized at 20 MPa would have high viscosity and sedimentation of large particles. The optimized HP was 67.5 MPa, which indicated that the benefit of increased HP was limited. Adjustment of pH is important in sterilized dairy beverage products since pH may affect the interactions between ingredients.