Microencapsulation of Spent Coffee Extract Within Saccharomyces cerevisiae Cells via Spray Drying and Evaluation of Its In Vitro Bioaccessibility

Abstract

Spent coffee is rich in bioactive compounds, including chlorogenic acid, caffeic acid, and caffeine, which offer health benefits. However, digestive processes can degrade these compounds; therefore, microencapsulation within Saccharomyces cerevisiae yeast cells offers a novel method to stabilize these bioactive compounds during digestion. In fact, it is important to mention that this technique of microencapsulation in Saccharomyces cerevisiae has not been previously applied to spent coffee extract. As a result, in this study, spent coffee extract was microencapsulated in non-plasmolyzed (NPCs) and plasmolyzed (PCs) yeast cells using the spray drying method. The physicochemical properties of the extract and the microencapsulates were characterized, and the bioaccessibility of the bioactive compounds was evaluated with digestion in vitro. Encapsulation efficiency (EE) was 38.62% for NPCs and 55.78% for PCs, with loading capacities (LCs) of 126.36 and 242 g/kg, respectively (according to Equations (1) and (2)). The presence of antioxidant compounds, identified by HPLC in spent coffee, was confirmed in the microencapsulates using FTIR. In vitro digestion assays revealed higher bioaccessibility of bioactive compounds in the intestinal phase, greater than 90%, and increased antioxidant activity in beer made with plasmolyzed microcapsules (BPM). These results suggest that yeast microencapsulation effectively stabilizes the bioactive compounds of spent coffee extract, releasing them throughout the gastrointestinal tract in vitro, mainly in the intestinal phase. Thus, microencapsulated compounds could serve as functional additives with a good percentage of intestinal bioaccessibility.