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

Abstract

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: chigh = 5.0% WPI + 1.0% pectin; cmed = 2.75 + 0.55%; clow = 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.