Protein-based hydrocolloids: Effect on the particle size distribution, tribo-rheological behaviour and mouthfeel characteristics of low-fat chocolate flavoured milk

Abstract

This work brings a relevant contribution to the development of dairy functional beverages by investigating the effect of protein hydrocolloids on the particle size distribution, flow behaviour and friction profile of low-fat chocolate-flavoured milk (Choc-FM_(SMP)). Three proteins were tested: gelatin, collagen hydrolysate (ColHdr) and microparticulate whey (MWhey). Our results revealed that the flow consistency coefficient (K) increased by the addition of the protein hydrocolloids without significantly affecting the particle size distribution (the majority of the particles did not exceed 40 μm). At the highest concentration level (1.5% w/w), ColHdr and MWhey presented K ~ 10 mPa sn. This represented a 4-fold increase in the K value obtained for Choc-FM_(SMP) (without hydrocolloid). Gelatin, however, reached a maximum K ~ 6 mPa sn for the upper-limit concentration tested (0.5% w/w). The magnitude of the coefficient of friction (CoF ~ 0.4 to 0.5) was not significantly affected by the type or concentration of proteins used. The friction trend (regimes), however, was mainly influenced by the protein type. The gelatin-based system was characterized by a prolonged mixed-regime. For ColHdr and MWhey systems, there was evidence that the cocoa particles promoted abrasive wear which, in turn, was assigned with a decaying trend of CoF and friction hysteresis at the dry-contact zone (sliding speed < 1 mm s−1). In both sensory and rheological measurements, the increase in thickness promoted by the hydrocolloids can be ordered, from high to low, as ColHdr ~ MWhey > gelatin. Creaminess and oiliness were ranked slightly higher for ColHdr than the gelatin-based sample.