Influence of pH on particle size of thermomechanical stabilized whey protein-pectin complexes for technical scale production

Abstract

Whey protein-pectin complexes (WPPC) with particle sizes d90,3 10 μm can be applied as fat replacer enhancing creaminess in fat reduced products. For the formation of process stable WPPC initial whey protein-pectin coacervates are formed via pH adjustment and denatured via thermomechanical treatment. The formation of WPPC was recently scaled up based on a reference process established at a batch lab scale scarped surface heat exchanger (90 °C, 675 s−1, 130 mL, pH 6.1). The application of three different whey protein sources was investigated resulting in poor applicability at previously established pH of 6.1 at the continuous technical scale scraped surface heat exchanger (90 °C, 675 s−1, 130 L⋅h−1). Based on ζ-potential and turbidity a pH range between 4.75 and 5.5 was chosen as suitable for the investigation in technical scale. While temperature and representative shear rate were maintained, whey protein pectin coacervate dispersions with pH between 4.75 and 6.0 were processed at the scraped surface heat exchanger. Depending on whey protein source a pH adjustment between 5.0 and 5.5 was necessary, to result in suitable particle sizes in targeted complex size d90,3 ∼10 μm. The pH can be applied as additional parameter, besides representative shear rate, temperature and biopolymer concentration, to tailor WPPC size for different product matrices for high perceived creaminess.