2.11. Glycemic Index In Vitro

The method of Reis and Abu-Ghannam [57] was adapted to evaluate the in vitro glycemic index (GI) of the muffins. The digestion procedure described above was used in this procedure. Digesta aliquots of 1 mL were taken at 20, 30, 60, 90, 120, and 180 min after the start of intestinal digestion in the tubes, with 4 mL of absolute ethanol used to deactivate the enzymes. The GOPOD method was used for determination of the glucose content in the samples (mg glucose/g sample). Glucose content was plotted as a function of time, and the areas under the hydrolysis curves (AUC) were calculated. The ratio between the AUC of the sample and the AUC for the reference food (white bread) was used to calculate the hydrolysis index (HI) values expressed as percentages, which were normalized for the total carbohydrate available in each sample and reference. The glycemic index was predicted according to the equation defined by Goñi, Garcia-Alonso, and Saura-Calixto [58]: