Sustainable use of coffee roasting by-products: development of high value-added gummy candies

The sustainable utilization of production wastes in the agri-food sector is an increasing challenge. This work aims to evaluate the applicability of coffee silverskin, the main by-product of coffee roasting, in the formulation of gummy candies. Firstly, the experimental plan envisaged the extraction and characterization of bioactive compounds from coffee silverskin. The influence of different concentrations of coffee silverskin extract (1%, 2%, and 4%) was then evaluated on chemical, physical, microbiological, structural, and sensory gummy candies characteristics for 120 storage days. Candies formulated without coffee silverskin extract were used as control. The results up to 120 days of storage revealed the higher quality of gummy candies enriched with 1%, 2% and 4% coffee silverskin extract not only for their bioactive content, ranging from 147.9 to 161.1 mg GAE Kg ^-1 of phenolic compounds, but also for their antioxidant activity, with values at the end of storage of 15.06, 30.25, 31.50 and 28.20 µmol TE g^-1 respectively in control and gummy candies enriched with 1%, 2% and 4% coffee silverskin extract. Moreover, all the candies enriched with silverskin coffee extract showed better physical and sensory characteristics compared to the control taste. The results show that the proposed use of silver coffee skin improves and preserves the quality of gummy candies and then be employed as an ingredient to improve the quality of confectionery products.