Wet-mixing improved reconstitution of powdered cocoa beverage

Abstract

This study investigated how wet-mixing affect powder structure and reconstitution of powdered cocoa beverage (PCB). Seven PCB samples were prepared from a single formulation, with different core ingredients (cocoa, skimmed milk, hydrolysed cereal extract, sucrose and palm olein) omitted from wet-mixing then added back by dry-mixing. Particle size and contact angle analyses indicate that wet-mixing merged ingredients with different particle sizes and hydrophilicities into more homogeneous particles with higher surface hydrophilicities, which also increased powder bulk porosity. Consequently, wet-mixing enhanced powder wettability and thus reconstitution rate of PCB. Meanwhile, fat-containing powders possessed lower particle surface hydrophilicities than fat-free powders but had shorter wetting and reconstitution times. Wet-mixing increased solubility of cocoa but also increased sedimentation rate and sediment volume in reconstituted PCB. Conversely, wet-mixing induced insoluble aggregation of skimmed milk proteins. Dissolved saccharides from hydrolysed cereal extract were essential in minimizing insoluble aggregation during processing.