Antioxidant Capacity Analysis of Blackberry Extracts with Different Phytochemical Compositions and Optimization of their Ultrasound Assisted Extraction.

High antioxidant capacity molecules, such as anthocyanins, occur naturally in blackberry (Rubus fruticosus). In particular, 'Dasha' blackberry cultivar has scarcely been studied and, it is becoming economically more important in Mexico. In this study, several blackberry extraction conditions, conferred different amounts of detectable phytochemical groups that in turn were analysed with a new approach to investigate their influence on antioxidant capacity (AC). Additionally, a central composite design (CCD) was proposed to study effects of temperature and acidification on AC. Finally, an original approach was used to disclose interactions between the phytochemical content and the AC. Changes in size of the particles during extraction were reported for the first time, and the results showed evidence of swelling and dissolving of particles. UAE of fine and thick powders achieved similar efficiencies in contrast with maceration which showed large differences for the extraction of the tested sizes. CCD showed that low levels of acidification and high levels of temperature resulted in higher extraction of phytochemicals and AC. HPLC show that the main anthocyanidin may represent 88% of the total anthocyanins. Due to its relatively high abundance, cyanidyn-3-glucoside showed evidence of being the main cause of the changes in AC in 'Dasha' extracts. The use of mild conditions resulted in no degradation of anthocyanins and, therefore, there are no AC losses. A correlation plane was proposed to study synergisms of the extracts with other anthocyanins or phenolics.