Encapsulation of coffee silverskin extracts by foam mat drying and comparison with powders obtained by spray drying and freeze-drying

Abstract

Coffee silverskin is a coproduct that has a rich composition in bioactive compounds. However, most of these compounds are susceptible to the conditions used during food processing and storage. Encapsulation is a process of great interest to increase the stability of these bioactive compounds, and different methods can influence the final characteristics of the product. Therefore, this study aimed to evaluate the encapsulation methods by foam mat drying, spray drying and freeze-drying for producing powder from coffee silverskin extracts. Density, porosity, overrun, and stability foam were evaluated and the physicochemical properties of powders, such as water activity, moisture, wettability, hygroscopicity, solubility, color, antioxidant activity, and total phenolic were determined. The optimal condition required for the feed mixture for foam formation was 7.6% gum arabic, 2% maltodextrin, and 10.4% egg albumin. All methods presented powders with desirable values of water activity, moisture content, and hygroscopicity, being considered stable for storage, and high content of bioactive compounds. Higher temperatures for foam mat drying produced powders with higher encapsulation efficiency (>77%) and longer wettability than lower temperatures (50 and 60°C). Therefore, this study verified that foam mat drying can be considered an efficient and promising method for encapsulating bioactive compounds from coffee silverskin extract.