Encapsulation of antioxidants from Spent coffee ground extracts by spray drying

Spent coffee grounds (SCG) represent a good raw material for the recovery of bioactive compounds. Indeed, SCG extracts are rich in antioxidants, particularly in chlorogenic acid (5-caffeoylquinic acid) (CGA) and melanoidins, which are able to prevent serious neurodegenerative and cardiovascular diseases. In order to preserve the activity of these compounds, encapsulation by spray drying can be used. In this study, an extract rich in phenolic compounds from spent coffee grounds was obtained by microwave-assisted extraction, using a mixture of ethanol:water 54:46 (v/v) as solvent, operative temperature of 150 °C, and extraction time of 90 min. Encapsulation process, using inulin and maltodextrin as coating agents, was studied by means of an experimental design and the response surface methodology was used for data treatments. Inulin:maltodextrin ratio and sample flow rate effects on encapsulation yield, efficiency and product features was evaluated. Results demonstrated that high encapsulation efficiency (63%) can be reached using inulin as the carrier, leading to the production of microencapsulated dried powders rich in polyphenols that can have potential industrial applications in food and cosmetic areas.