Determination of the Optimal Mixture of Wall Materials for the Encapsulation of Cacao Pod Polyphenols by Spray Drying Using Response Surface Methodology

Cacao pod husk (CPH) and cacao mucilage (CM) are abundant underutilized by-products with potential as sources and carriers of phenolic compounds. This study evaluated wall-material mixtures for the spray-drying microencapsulation of a polyphenol-rich cacao pod husk extract using an I-optimal mixture design and response surface methodology. Cacao mucilage solids, inulin, polydextrose, and sodium alginate were investigated. Process yield was the only response adequately described by the fitted model and was therefore used as the model-based response for formulation selection, whereas polyphenol recovery, encapsulation efficiency, total phenolic content, moisture content, and antioxidant capacity were evaluated experimentally. The selected formulation contained 20% CM solids, 0.65% inulin, and 79.35% polydextrose, without alginate. Experimental validation yielded a process yield of 79.93%, polyphenol recovery of 72.45%, and encapsulation efficiency of 87.95%. The resulting powder contained 4.13 mg GAE/g total polyphenols and showed an antioxidant capacity of 7.94 µg TE/g, moisture content of 3.21%, and water activity of 0.225. Microcapsules were predominantly spherical (D50 = 7.66 µm). DSC showed a Tg of 58.29 °C and additional transitions but did not establish a definitive thermal-stability limit. The findings support cacao by-products as functional spray-dried powders with low initial moisture and water activity in a circular-economy approach.