Determination of processing conditions for industrial manufacture of pre-denatured WPC : a thesis presented in partial fulfilment of the requirements for the degree of Master in Food Technology

Abstract

The purpose of this study was to establish processing conditions for manufacturing denatured whey protein concentrate (WPC) with the ability to form self-supporting gels upon addition of water with minimal or no heating. Such product could be used as thickening and gelling agents in various food applications. In the preliminary studies, fresh whey and ultrafiltrate (UF) retentate solutions were heated and analysed using polyacrylamide gel electrophoresis (PAGE). The results showed that heating 1% protein solution of retentate (pH 7.0) at 80°C for 20 min formed the desired "soluble" aggregates. Those aggregates were predominantly formed at lower protein concentration compared to that at higher protein concentration. Much larger aggregates were formed when acid whey was heated under similar conditions. The same heating conditions (1% retentate solution, pH 7.0, 80°C for 20 min) were used in two different pilot plant trials (Massey University and Anchor Products) to produce denatured WPC powders. The denatured WPC powders were capable of forming viscous solutions or gels at ~ 10% protein concentration upon re-hydration and addition of GDL, CaCl2 or NaCl at ambient temperatures. By contrast, the unheated WPC solutions did not gel under these conditions. The viscosity or gel strength of the denatured WPC solutions increased with protein concentration, incubation time and temperature in the presence of additives. The heat-denatured WPC powders produced in the pilot plants had desirable functional properties. The high viscosity and the ability to form a gel upon addition of GDL or salts at 5-40°C would enhance their application in food systems, such as in comminuted meat, pressed ham/bacon, mayonnaise and yoghurt products.