Characterization of Coffee Silverskin from Different Origins to Evaluate Its Potential as an Ingredient in Novel Food Products

Coffee silverskin is generated in large quantities as a co-product during the roasting process of coffee beans. This co-product is rich in bioactive compounds that offer potential health benefits, justifying its consideration as a functional ingredient in food. In this study, silverskin from the species <i>Coffea arabica</i> and <i>Coffea canephora</i> from six different countries was characterized to highlight its potential and applicability as a safe ingredient in new food formulations. The results revealed a dietary fiber content ranging from 71.81 to 76.86 g/100 g, with a high portion of insoluble fiber ranging from 54.02 to 60.58 g/100 g. The mineral content showed that, in all samples, potassium and calcium were the main elements with values ranging from 6.66 to 17.57 mg/g and from 9.25 to 16.44 mg/g, respectively. The caffeine content was quantified with levels ranging from 0.81 to 7.32 mg/g. In addition, high levels of phenolic compounds were identified in free and bound forms, with 5-caffeoylquinic, 3-caffeoylquinic, 4,5-dicaffeoylquinic, and ferulic acids being the main components in both fractions. All samples analyzed showed a good antioxidant capacity in the four different methods used, with values ranging from 8.12 to 10.85 mg Trolox Equivalents (mgTE/g) in the DPPH assay; from 9.69 to 19.68 mgTE/g in the FRAP assay; from 5.96 to 11.05 mgTE/g in the FRAP assay; and from 0.21 to 1.11 and 4.69 mg EDTA/g sample in the FIC assay. In conclusion, coffee silverskin has the potential to play a beneficial role as an ingredient in new food formulations, thus contributing to the development of a circular economy in the food industry.