Cocoa hulls polyphenols stabilized by microencapsulation as functional ingredient for bakery applications

Cocoa hulls are a potential source of polyphenols to be used as functional ingredients in foods, but their low stability to oxidation and thermal degradation limits their practical application. The aim of this study was to microencapsulate cocoa hulls phenolic extracts through spray-drying, in order to produce new heat stable ingredients for bakery products. Polyphenols were extracted using water and ethanol under different conditions. The best performing extract (water/ethanol 50:50), containing 93.3 mg of total polyphenols per gram of dry extract, was spray-dried with and without stabilizing agents (maltodextrins and/or gum Arabic), obtaining seven different powders. These were first tested for their stability, showing a total phenolic content and an antioxidant activity stable up to 90 days. The powders were then used to evaluate their baking stability in a model biscuit; the micro encapsulation using an 80:20 ratio of maltodextrins to the dry extract allowed obtaining the most stable powder, with a total polyphenol content unaffected by the baking process.