0514 Effects of sodium polyphosphate on distribution of particle size of polymerized whey protein

Abstract

Protein-based fat replacers have been used in dairy foods for many years. The objective of this study was to develop a novel fat replacer using whey protein concentrate (WPC). WPC was heated with sodium tripolyphosphate (STPP) to prepare polymerized whey protein particles as fat replacer for nonfat dairy product formulation. The effects of STPP concentration (0–1%, wt/wt), protein content (8–10%, wt/vol), pH (7.5–8.5), heating temperature (70–85°C), and time (5–25 min) on the particle size distribution were investigated. Results showed that heating WPC solution (8.0%, wt/vol) with 0.4% STPP at pH 7.5 at 85°C for 5 min resulted in 40% of particles in the range of 1–3 μm, which were as large as fat globules in dairy products. There were no large particles ( > 10 μm) yielded when 0.4% STPP was added, but higher STPP levels ( > 0.5%) produced larger particles ( > 10 μm) at a unimodal distribution. The percentage of particle size between 1 and 3 μm decreased with increasing WPC concentration. A wide distribution or even multi-peaks with more large particles ( > 10 μm) were observed when the mix was heated at higher pH values (8–8.5). When heating the mix at 70–85°C for 5 min, 20%-40% of the particles were in the range of 1–3 μm and prolonged heating time also generated large particles ( > 10 μm). Results indicated that heating whey protein concentrate with STPP could produce particles/aggregates that might be suitable as fat replacer for non or low fat dairy products.