Effect of mixing time, freeze-drying and baking on phenolics, anthocyanins and antioxidant capacity of raspberry juice during processing of muffins

BACKGROUND: Consumption of baked products constitutes an important part of a daily breakfast considering that people are continually grabbing meals on the go. Among baked products, muffins rank third in breakfast products and attract a broad range of consumers. Incorporation of red raspberry juice into muffins can add value to the product while preserving health benefits to the consumer. The purpose of this study was to evaluate the effect of mixing time, freeze-drying and baking on the phenolic and anthocyanin contents and antioxidant capacity of raspberry juice during the preparation of muffins. RESULTS: Freeze-drying of raspberry batters reduced their phenolic content and antioxidant capacity regardless ofmixing time. Non-freeze-dried raspberry batter mixed for 5 min had the highest phenolic content (0.88 mg gallic acid equivalent g-1 dry matter (DM)). Non-freeze-dried raspberry muffins had the highest antioxidant capacity (0.041 mu mol Trolox equivalent g-1 DM). Freeze-dried raspberry batters mixed for 5 and 10min had the highest anthocyanin content (0.065 mg cyanidin-3-glucoside g(-1) DM). Baking reduced the anthocyanin content of both non-freeze-dried and freeze-dried raspberry muffins. CONCLUSION: Despite the reduction in valuable compounds, muffin is a vehicle for the delivery of these compounds. (C) 2012 Society of Chemical Industry