Effect of processing on potato starch: in vitro availability and glycaemic index

The content of digestible starch (DS) and resistant starch (RS) in processed potatoes was assessed. In addition, the effect of domestic cooking on the in vitro digestibility of starch in this tuber, which may influence the glycaemic response, was studied. Resistant starch in raw potato is high, however different RS values were obtained when processed, ranging from 1.18% in boiled potatoes to 10.38% in retrograded flour. In general, cooked potatoes have high levels of DS. Starch digestibility is improved after processing and it is affected by the cooking methods. Boiled and mashed potatoes showed the highest rate of digestion, on the contrary raw potato was hardly digested. The estimated Glycaemic Index (GI) from the degree of starch hydrolysis within 90 min was in accordance with the reported GI values, for potatoes processed in the same way.