Effect of Cheese pH and Temperature on Serum Phase Characteristics of Cream Cheese During Storage

Three 13.6‐kg blocks of cultured cream cheese manufactured on different days were obtained from a commercial source within 2 wk of manufacture. Blocks were sectioned into samples that were randomly assigned to 3 treatments. A model system was used to change cheese pH. One group of samples was exposed to volatile ammonia to increase the pH to about 5.3. A 2nd group was exposed to volatile acetic acid to decrease the pH to about 4.5. A 3rd group served as a control (pH about 4.8). Samples from each pH treatment were vacuum‐packaged and randomly assigned to 1 of 2 storage temperatures: 4 °C and 20 °C. Samples were randomly chosen for analysis after 4, 8, 12, 16, 20, 24, and 28 d of storage and centrifuged at 12500 ±g for 75 min at 25 °C to obtain expressible serum (ES). The ES was analyzed for viscosity at 25 °C. Effects of pH treatment, storage time, and storage temperature were evaluated by analysis of variance (ANOVA) according to a split split‐plot design. The amount of ES increased significantly during storage and was affected by storage temperature and cheese pH. Significantly more ES was obtained at higher temperature and higher pH. Viscosity of ES decreased significantly during storage and was affected by storage temperature and cheese pH. Viscosity decreased more rapidly at higher temperature and higher pH. The data suggest that higher temperature and higher pH resulted in accelerated loss of stabilizer function during storage, possibly due to microbiological degradation of the stabilizer.