BIOACTIVE POTENTIAL OF SUNFLOWER MEAL AFTER SIMULATED DIGESTION CONDITIONS

The sunflower (Helianthus annuus) is an annual plant, native to the Americas, but widely cultivated throughout the world, mainly due to its ability to adapt to drought and temperature variations. Sunflower seeds are mainly composed of oil (between 40 to 45%, with some varieties reaching 60%), protein, and fiber. After oil extraction, large amounts of by-products are generated, such as defatted flour (DF), which can be used for human food and nutrition. This study aims to characterize and evaluate the antioxidant and hypoglycemic potential of compounds obtained from DF, which underwent simulated gastrointestinal digestion. For this to be possible, the INFOGEST protocol was followed, passing through the oral, gastric, and intestinal phases. After this process, a soluble and an insoluble fraction were obtained, in which the soluble fraction represents what would be absorbed by the body. While the insoluble fraction represents the fibrous components that are not digested by gastrointestinal enzymes. Physicochemical composition, amino acid profile, and molecular weight distribution of proteins and peptides of the DF and the soluble fraction (SF) were characterized. In order to assess the bioactive potential, the SF was analyzed for its hypoglycemic and antioxidant activities, using the DPPH, ABTS and ORAC methods. In addition, the SF presented a profile of essential amino acids, highlighting leucine, valine, phenylalanine, and isoleucine, but deficient in lysine. The molecular mass profile showed that 72.45% of the soluble protein components of SF had a low molecular weight (<2 kDa), which is a favorable characteristic for bioactive peptides. There was a significant increase in antioxidant potential of the SF when compared to flour (DF). The best results in the DPPH and ABTS methods for SF were obtained by using methanolic extract with 126.9 and 147.3 µmol Trolox Eq./g sample, respectively. However, the results obtained by the ORAC method in the aqueous extract showed the highest antioxidant activity (1,013.4 µmol Trolox Eq./g sample) when compared to the DF samples (936.0 µmol Trolox Eq./g sample). Regarding the hypoglycemic potential, the SF showed 71% α-amylase enzyme inhibition at concentration of 0.05 g/mL of aqueous extract. The presence of low molecular weight peptides associated to phenolic compounds may be responsible for the results obtained regarding bioactive potential, increasing possibilities for an intelligent and integral use of the co-product of the oil industry.