Whey protein-pectin complexes as fat replacer: Structural effects of spray drying

Abstract

The application of thermomechanical treatment on technical scale enables the formation of process-stable whey protein-pectin complexes (1–40 μm) suitable as fat replacers. The impact of subsequent spray drying on particle size, ζ-potential, contribution of pectin and protein to the complex structure, and voluminosity was investigated. Results showed that spray drying reduced particle size d_3,2 by a factor of 1.3–2.0, depending on the whey protein source. After spray drying, there was a decline in the absolute amount of electrostatically stabilized pectin and protein, accompanied by an increase in free protein and pectin, depending on the whey protein source, suggesting that the rearrangement of prior interactions was not feasible. Results were supported by ζ-potential determination. Voluminosity, measured by intrinsic viscosity after thermomechanical treatment, ranged from 11.6–18.9 mL g⁻¹ depending on the whey protein source, while the volume fraction-based method yielded lower values (3.6–6.6 mL g⁻¹), as it only represents the WPPC core structure and does not take the electrostatically stabilized pectin shell into account. Similar results (3.6–7.0 mL g⁻¹) were observed for WPPC after spray drying, confirming that rearrangement of prior interactions was not feasible. The impact of spray drying on complex characteristics needs to be considered for fat replacer applications.