Influence of shear stress, pectin type and calcium chloride on the process stability of thermally stabilised whey protein-pectin complexes

There is a strong demand for fat-reduced foods due to an increasing incidence of overweight and obesity. To overcome the sensory deficiencies going along with a fat reduction, process stable fat replacers with tailored properties, such as whey protein-pectin complexes, are necessary. In this study, the effects of process (shear rate: 0, 150, 500 s(-1); scale: lab/pilot plant) and composition (pectin type: high/low degree of blockiness; CaCl2: 0, 15, 30 mM; biopolymer concentration: c(high) = 5.0% WPI + 1.0% pectin; c(med) = 2.75 + 0.55%; c(low) = 0.5 + 0.1%) parameters on micro-and macro-structural characteristics of whey protein-pectin (WPI-pectin) complexes were investigated. Thermomechanical treatments of WPI-pectin suspensions in a high-pressure double gap geometry revealed a high shear stability during complex generation at 500 s-1. The degree of blockiness (DB) of pectin was identified as critical parameter influencing complex structure and biopolymer system stability. WPI-pectin complexes with a high DB pectin had a fragile structure low DB resulted in a compact structure. The shear rate was the main parameter to adjust yield and particle size, both on the lab and pilot scale. A higher shear rate led to a higher yield consisting of smaller particles. This effect could be partially compensated by medium CaCl2 concentrations (<= 10 mM) or high biopolymer concentrations ( <= 5.0% (w/w) WPI + 1.0% (w/w) pectin). Modelling the parameter effects resulted in sets of processing and composition parameters suitable for the generation of WPI-pectin complexes, owning the potential as fat replacers.