Impact of food processing on the glycemic index (GI) of potato products

Potatoes are one of the most popular carbohydrate foods in industrialized and some developing countries. However, contradicting arguments and misconceptions on potatoes as a high glycemic index (GI) food is directly affecting potato consumption during the past years. Potato varieties, maturity level, starch structure, food processing techniques and composition of the meal contribute to the GI of potatoes. Domestic boiling, baking, microwave cooking, oven cooking, extrusion and frying result in different degrees of gelatinization, and the crystallinity of starch in potato. French fried potatoes contain more resistant starch whereas boiled and mashed potatoes contribute to significant digestible starch. Extrusion processing conditions could affect the starch physicochemical structure and resulting nutritional value. Extrusion cooking makes more gelatinized starch than conventional cooking methods. Cooling or storing after processing of potatoes significantly reduces the GI due to retrogradation of starch molecules. This review provides a brief idea about the glycemic index, glycemic load, and their importance to human diseases, and detail information on the effect of food cooking methods on the glycemic index of potatoes.