In vitro starch hydrolysis and estimated glycemic index of tef porridge and injera

- High amylose tef flours did not necessarily resulted in lower eGI porridge and injera.
- Varieties with high RS and SDS native starch did not necessarily exhibited lower eGI.
- The eGI of fresh porridge and injera of all tef varieties ranged from medium to high.
- Fresh porridge and injera of tef may not be good alternative to diabetic people.

The aim of this study was to investigate the in vitro starch digestibility of injera and porridge from seven tef varieties and to estimate their glycemic index. The total starch, free glucose, apparent amylose, resistant, slowly digestible and rapidly digestible starches of the varieties ranged between 66 and 76, 1.8 and 2.4 g/100 g flour dry matter (DM), 29 and 31%, 17 and 68, 19 and 53, 12 and 30 g/100 g starch DM, respectively. After processing into injera and porridge, the rapidly digestible starch content increased by 60-85% and 3-69%, respectively. The estimated glycemic index of porridge and injera of the varieties ranged 79-99 and 94-137 when estimated based on model of Goni et al. (1997) whereas from 69 to 100 and 94 to 161, respectively based on Granfeldtet al. (1992). Tef porridge and injera samples studied here can be classified as medium- high GI foods, not to be considered as a proper food ingredient for diabetic people and patients in weight gain control.