Resistant starch content and glucose release of different resistant starch commercial ingredients: effect of cooking conditions

The suitability of different commercial ingredients rich in resistant starch (RS), two granular RS (RS type 2) and two retrogradated RS (RS type 3), as sources of RS in different enriched foods (muffins, and battered food prepared by two methods differing in their thermal treatment) was studied. The appropriateness of the official method of fibre analysis to detect RS and the application of RS in muffins to reduce the glucose released during in vitro food digestion were also investigated. In RS-enriched muffins, the RS content resulted not affected by oven baking. In fried battered food, a reduction of RS content took place after frying, this reduction being dependent on the type of RS-ingredient. In general, RS type 3 ingredients showed higher cooking stability than RS type 2. The thermally milder method for fried food showed higher final RS content in comparison with the thermally more severe one. In vitro simulation of human digestion showed lower glucose release in RS-enriched muffins, especially in RS type 3, in comparison with the control (no RS). Although RS is considered dietary fibre, the official method of fibre analysis (AACC International 32-07.01-AOAC 991.43) underestimated its content value in comparison with the official method for RS analysis (AACC 32-40.01-AOAC 2002.02).