Influence of different processing methods on the glycemic index of potato (Nicola)

Potato is a food which yields very variable glycemic responses. It makes a major contribution to total starch intake and the share of processed potato products is growing. The aim of the study was to determine the effects of processing and storage on the glycemic indices (GIs) of industrially processed potato products.Two groups (11 and 10 volunteer subjects) attended a glucose tolerance test and glycemic response test of 4 and 3 processed potato products, respectively. GIs of different potato products were calculated for each subject using their own glucose tolerance test and glycemic responses for test meals and averages calculated for each product.GIs of freshly prepared potato products were high: steam boiled potatoes 104±39, oven-baked casserole 95±30 (carbo-peeled sliced potato) and mashed potatoes 106±42. GIs of cooled and cold stored potato products were intermediate, potato cubes served cold 76±32 and cooled, reheated oven-baked casseroles 73±25 (carbo-peeled sliced potato), 75±17 (carbo-peeled mashed potato) and 81±28 (steam-peeled mashed potato). Cooling and cold storage decreased GIs significantly (steam boiled potatoes vs. steam boiled potato cubes (P=0.01P=0.01), freshly served casserole made of sliced potatoes vs. casserole cooled, cold stored and reheated P=0.01P=0.01).ConclusionCooking method, peeling method, or slicing or mashing did not affect the GIs. Cooling and cold storage, despite reheating, lowered GIs of potato products by about 25%.