HYPOGLYCEMIC ACTIVITY AND BIOACCESSIBILITY OF PHENOLIC COMPOUNDS OF YACON SYRUP

Yacon (Smallanthus sonchifolius) is plant native to the Andean region and a rich source of fructooligosaccharides and phenolic compounds, particularly chlorogenic acid. The aim of this study was to evaluate the glycemic index of yacon syrup and the bioaccessibility of its phenolic compounds. Yacon syrup was produced by Embrapa Agroindústria Tropical. The roots were first subjected to acid treatment and then with cellulolytic and pectinolytic enzymes, and filtered using a microfiltration system. The glycemic index was estimated in vivo by comparing the glycemic response of yacon syrup to glucose intake at times 15, 30, 45, 60, 90, 120 minutes in eleven volunteers. The total phenolic content was determined by the Folin-Ciocalteau method and the antioxidant activity was investigated by ORAC and ABTS assays before and after in vitro digestion was performed by digestive enzyme assisted hydrolysis. The results shows that yacon syrup had a low glycemic index (47±4). In addition, the total phenolics present in digested and undigested samples were 149.0 and 55.3mg chlorogenic acid equivalent/mL of yacon syrup, respectively, considering p < 0,001. The antioxidant activity by ORAC assay varied between 141.3 and 264.0μM of Trolox equivalents/mL of sample (p=0,003) and values by ABTS assay varied between 94.9 and 277.8mmol equivalent Trolox/mL in the digested and undigested samples, respectively (p<0,001). The phenolic profile found in the undigested samples was chlorogenic acid (7.5mg/mL) and caffeic acid (0.75mg/mL). Also, considering the in vitro digestion of samples, it was possible to observe that chlorogenic acid (11.5mg/mL); caffeic acid (0.5mg/mL), p-coumaric (0.3mg/mL) and ferulic acid (0.7mg/mL) were bioaccessible. Moreover, it’s possible observed the presence of others compounds in after digestion. In conclusion, yacon syrup had a hypoglycemic effect in vivo and maintained its antioxidant activity and its bioaccessible phenolic compounds after in vitro digestion.