Stability of a cyanidin-3-O-glucoside extract obtained from Arbutus unedo L. and incorporation into wafers for colouring purposes.

An extract from Arbutus unedo fruits, rich in anthocyanins, was studied as a natural colorant with bioactive properties (antioxidant, antimicrobial and cytotoxic). The aqueous stability of the extract was monitored using the anthocyanins' content as response (determined by HPLC-DAD) in function of time, temperature and pH. Aided by mechanistic/phenomenological models, the conditions that favours the stabilization of the extract were provided, highlighting the suitability of the colorant for pastry/bakery products. As a case study, the extract was incorporated into wafers and the changes on the nutritional profile, free sugars, fatty acids and antioxidant properties were monitored during 6 days of storage. The results provide information for: i) potential application of the rich extract in anthocyanins for producing a natural colorant with bioactive properties; and ii) shelf-life predictions. The extract incorporation did not cause changes in the nutritional components of wafers but added colorant and antioxidant properties.