| Beverages formulated with whey protein offer consumers many health benefits. A challenge, however, is that during thermal processing, which is used to ensure safety and extend shelf life, a small portion of protein can become denatured and aggregate. Insoluble protein aggregates cause an unappealing precipitate and increased turbidity. Addition of ingredients in the 3.0 to 4.0 pH range was explored to reduce turbidity. At pH 3.8 to 4.0, ingredients were crucial to clarity. At pH 3.6 and below, samples were clear, regardless of the ingredient added.;Protein aggregation also occurs during storage, resulting in an increase in turbidity and insoluble protein aggregates and a decrease in soluble protein. Loss of soluble protein followed second-order kinetics and Arrhenius behavior. Processing, ingredients, pH, and protein aggregation affected clarity and shelf life. An understanding of these factors assists in the development of clear, shelf-stable beverages containing whey protein.;GMP, found in whey, is the only naturally-occurring protein that contains no phenylalanine (Phe) in its pure form, and is of interest as a dietary source of protein for individuals with phenylketonuria (PKU), a genetic disorder diagnosed at birth. Commercially-available GMP contains too much Phe from residual whey proteins for phenylketonurics. The Phe concentration in crude GMP was reduced 47% using ion exchange chromatography and ultrafiltration. Purified GMP was supplemented with limiting amino acids and used in GMP foods to test its safety in the management of PKU.;To address the need for a high throughput, low-cost process to produce high purity GMP, the impact of co-purifying whey components on GMP binding capacity of 10 commercially-available anion exchange resins was tested. An industrially relevant flow rate, no extensive pre-treatment of whey, and inexpensive food-grade buffers were used to test GMP capacity at a conductivity and pH representative of whey. A high capacity resin was found, but the capacity of all resins was negatively affected by co-purifying whey components. Identification of co-purifying whey components provided insight to the development of a process to better isolate high purity GMP. |
