Retention of bioactive compounds and bifidogenic activity of burdock roots subjected to different processes

Abstract

Burdock root in natura has compounds with functional activity. However, few studies have evaluated the retention of these compounds after thermal processing. Thus, the present study aimed to evaluate the retention of functional compounds in burdock root-derived products. The processes consisted of blanching (98 °C/4 min; BR1) followed by cooking in oil (95 ± 4 °C/10 min; BR2), root infusion (2%, 98 °C/10 min; BR3), the infusion residue (BR4); as well as the production of two types of chips: roasted burdock roots (120 °C/20 min; BR5) and fried burdock roots (150 ± 4 °C/4 min; BR6). All samples were evaluated for the content of total phenolics (TPC), antioxidant capacity (AC), total fructooligosaccharides (FOSt), and bifidogenic activity in vitro. The control (BR1) presented TPC of 162.07 mg gallic acid equivalents (GAE)/100 g, AC of 0.42 μmol Trolox equivalent/100 g, and 0.71 g/100 g of FOSt. These levels changed significantly for all processed products (BR2 to BR6) (p < 0.05) when compared to the control, with a reduction of 46–99% of TPC (BR4 and BR6), 47%–99% of AC (BR5 and BR6) and 40–63% of FOSt (BR5 and BR6). The results showed that the retention of TPC, AC, and FOSt in burdock-derived products was affected by thermal treatment, which should be considered during root processing. Roasted burdock chips have proven to be an alternative for a new convenience product with functional properties.