Engineering effects of hydrocolloids on drying kinetics, powder characteristics, and antioxidant preservation in grape powder

Abstract

This study explores the preservation of bioactive compounds in grape powder via encapsulation using spray drying, focusing on the impact of hydrocolloids—whey protein isolate (WPI), gum arabic, and high methoxy pectin—on critical engineering parameters. The research analyzes the effects of these encapsulants on rheological properties, drying kinetics, droplet formation, and drying curves, all of which influence the powder's morphology and antioxidant retention. Drying times ranged from 1.05 to 1.14 s, with distinct drying curves reflecting the relationship between moisture content and time, correlating with key powder properties such as bulk and tap density, flowability, and compressibility. Dimensionless numbers, including Peclet and Reynolds numbers, showed significant correlations with both powder characteristics and bioactive retention, highlighting the role of efficient heat and mass transfer in preserving phenolic content. The study concludes that optimal formulations, particularly those combining WPI and pectin, result in uniform droplet sizes, faster drying rates, and enhanced bioactive stability, providing insights for optimizing spray drying processes to produce high-quality, stable food powders.