Resistant Starch Production from Non-conventional Starch Sources by Extrusion

The production of resistant starch from non-conventional sources using an extruder was studied. Starch was isolated from unripe banana and mango fruits, commercial corn starch was used for comparison purposes. Moisture, ash and fat content were higher in non-conventional starch sources than in corn starch, but corn starch presented a lower protein and dietary fibre content than banana and mango starches. Amylose content was higher in banana and mango starches than in corn starch. Besides, mango had the smallest granule size (5–10 m). Extruded mango had the lowest solubility which may be related with the granule size, and in the case of the swelling, extruded products from corn starch had the highest values, a pattern that may be due to the amylose/amylopectin ratio, because corn starch had the lowest amylose content of the starches studied. Extruded products from mango presented a resistant starch (RS) content that decreased when the screw speed increased, for banana starch, the RS values from the extruded products was similar at 30 rpm and 65 rpm, and at 40 rpm it was the highest. In the case of retrograded resistant starch (RRS), the values of the extruded products prepared with non-conventional starches had a defined pattern, because they decreased when screw speed increased.