Coffee silverskin as a new functional ingredient in bakery products.

The coffee silverskin (CS) remains adherent to the green bean and is removed only during the roasting process, so easily found in the roasting plants. Currently it is used as fuel or fertilizer, but recent studies have shown the potential application in the food industry and food product formulation as functional ingredient, because of its low amount of fat and carbohydrates, high in dietary fiber and marked antioxidant activity. Aim of this study was the evaluation of the effects on the quality properties of bakery products added with coffee silverskin (CS). A model sponge cake formulation was used and products with 5% of CS (% on the flour weight) or without CS (reference) were prepared. In order to increase the nutritional value, CS was subjected to a alkaline hydrogen peroxide treatment. Chemical, physical and physico-chemical analyses (before and after the pre-treatment of the film) of CS were performed. Texture, image analysis and sensory tests of the CS-added and reference sponge cake were carried out. Results of the analyses evidenced that the addition of CS was an interesting ingredient. No main differences were determined on the chemical properties. Dynamometric measurements showed slight differences due to CS addition on texture while colour was mainly affected as the coffee silver skin led to a yellow-brown colour of the cake. Sensory properties resulted affected by the addition of the CS ingredient with differences in both appearance and perception of taste and smell but the overall acceptability of both products resulted high. This preliminary study confirm the high potential of this by-product of the coffee processing as food ingredient in bakery products by contributiung to improve its nutritional and health properties with a high soluble fiber and low caloric value.