Changes in bioactive components and antioxidant capacity of maqui, Aristotelia chilensis [Mol] Stuntz, berries during drying

Thermal processing is known to affect the content of the bioactive compounds and antioxidant activity. In this study drying assays were conducted on maqui berries (Aristotelia chilensis) between 40 and 80 degrees C and a constant airflow of 2 m/s. Total phenolics, flavonoids, anthocyanin, free and bound phenolic acids, beta-carotene, tocopherols, vitamin B as well as antioxidant activity as ORAC and DPPH values were determined. Evaluation of drying behaviour showed that at 80 degrees C equilibrium moisture content is reached after 300 min, while at 40 degrees C a drying time of 1080 min is needed, whereby degradation of bioactivity is more affected by the higher thermal load, which is observed on the berries at lower temperature. The content of total phenolics was found highest at 60 degrees C, while that of total flavonoids was highest at 70 degrees C, with a better correlation to DPPH values compared to ORAC values. The degradation behaviour of alpha- and gamma-tocopherol, was also investigated and resistance to degradation was found highest at 70 degrees C. Results of the present study provide a valuable tool to harness drying process of maqui berries. (C) 2015 Elsevier Ltd. All rights reserved.