Sorghum gluten free pasta: In vitro digestion and dialyzable antioxidant activity

PALAVECINO, P.; BUSTOS, M.C.; LEÓN, A. E.; RIBOTTA, P. D.

Rennes

Congreso; 5th International Conference on Food Digestion; 2017

Wheat flour may be replaced for sorghum flour in gluten-free products such as pasta, as it is devoid of gluten. The aim of present work was to study the nutritional attributes of sorghum pasta made from white (WSP) and brown (BSP) hybrids during in vitro digestion. First an estimation of glycemic index (eGI) was performed and then a dialysis tube was included to INFOGEST in vitro method to asses bioaccesibility of starch, polyphenols (TPC) and antioxidant activity (FRAP and ABTS methods) during gastric and intestinal phases. In addition, a non-linear fit was performed in starch hydrolysis curves obtained during digestion to asses kinetic parameters of digestion. The eGI was ~64 for both samples, with no significant differences in kinetic constant (~0.014 min-1) and adjusted percentages of hydrolyzed starch been 55.0 and 51.0 for WSP and BSP, respectively. In this regard, the hydrolyzed starch determined through INFOGEST modified method was similar (~55%) to the one determined by the in vitro digestion method for eGI, in both samples. Bioaccessible starch were also very similar for both gluten free pasta, been ~35 g /100 g starch (dialyzable starch was ~20 g/100 g starch). The kinetic constants were 0.172 and 0.144 min-1 for WSP and BSP during gastric phase and 0.029 and 0.017 min-1 intestinal phases respectively. Polyphenols, reducing power and radical scavenging activity were determined in cooked pasta, been higher for BSP. During digestion, TPC increased 2.9 and 2.4 times for WSP and BSP respectively. Radical scavenging activity of BSP was higher than BSP in bioaccessible fraction (980 μmol trolox/100 g). In conclusion, besides no differences were determined between white and brown sorghum flour in relation to starch hydrolysis extent and rate, some differences were found in in vitro antioxidant activity. It is remarkable that similar results were find with both techniques with clearly shows the potential of INFOGEST method to estimate glycemic index.