Phenolic Profile and Antioxidant Potential of Beverages from Buckwheat and Side Streams after Beverages Production

Plant-based milk alternatives are a fast-growing segment of food industry resulting in the generation of large amounts of by-products, often containing comparable and even higher amounts of valuable phytochemicals than the target products. Common buckwheat (Fagopyrum esculentum M.) Panda variety has been selected for this study, which aims to compare the antioxidant potential of beverages produced from buckwheat whole and dehulled grains, as well as cakes obtained as residues. After combining, evaporating and freeze-drying, extracts were subjected to RP-HPLC-DAD, total phenolics and in vitro antiradical and antioxidant assays (FRAP, ABTS, DPPH and lipid autoxidation). Flavonoids (3.09 mg/100 mL) exceeded the content of phenolic acids (2.35 mg/100 mL) in the beverages prepared from dehulled grains, but their content (1.69 mg/100 mL) in the beverages from whole grains was lower than that of phenolic acids (2.93 mg/100 mL). The antiradical capacity of beverages did not differ significantly, regardless of the method used. In case of by-products, a higher ferric-reducing capacity and scavenging activity towards DPPH center dot of cakes from whole grains compared to that from dehulled grains was established. The activity of cake extracts under lipid autoxidation conditions increased with the increase in their concentrations from 0.12 wt% to 0.16 wt% in the oxidizable substrate.