Effect of hydrocolloid type and concentration on in vitro starch digestibility of stored tortillas using response surface methodology

Tortillas were prepared using four commercial hydrocolloids. Experimental design with independent variables (storage time and hydrocolloid concentration) produced 12 samples for each hydrocolloid, that were studied using response surface methodology to know the effect of these variables on available starch (AS), resistant starch (RS) and retrograded resistant starch (RRS) contents. AS was affected by the storage time of the tortillas and the hydrocolloid concentration, apart from when the different gums were compared, differences were found in the values. The model obtained explains the RS formation in tortillas with high precision, as a high correlation coefficient and low p values were obtained. For RRS tortillas with Carboxymethyl Cellulose (CMC) and Arabic gum the model can accurately be used, with correlation coefficients of 0.82 and 0.87, respectively; the precision of the model for predicting the RRS formation in these tortillas were of 97 and 99%, respectively. The model obtained should be used with caution, but it can be considered adequate to study response tendencies. (c) 2005 Elsevier Ltd. All rights reserved.