Effect of Processing Temperature and Storage Time on Nonfat Dry Milk Proteins

Changes in physicochemical properties of pooled nonfat milk preheated to 63°C (I), 74°C (II), and 85°C (III), before spray‐drying were examined. Insoluble material from III contained more protein (particularly at reduced pH) and more coagulated protein‐lactose aggregates than either I or II. Soluble material from III was practically depleted of whey proteins which were utilized to form complexes stabilized through disulfide bonds. Milk protein micelles from III were heavier (ca 1 × 10 11 g/mole) than either I or II. An unsweetened milk‐orange juice blend, which was pasteurized at 63°C for 30 min and stored at 4°C, developed a precipitate which contained more protein and pectin, but less sucrose than the supernatant.