The In Vitro Digestibility of Carbohydrates in Boiled and Processed Potatoes
The fate of dietary carbohydrates in eight potato cultivars was determined in vitro by their rapidly available glucose content (RAG), slowly available glucose content (SAG), and total glucose (TG) content. Different preparation and processing techniques were included for three cultivars each. The relative share of RAG to TG varied between cultivars (55 to 78%) irrespective of the individual cooking behaviour. The preparation techniques indicated cultivar-specific behaviour. Peeling enhanced the relative RAG in two of three cultivars. Microwave heating had a positive effect upon SAG, but RAG was also enhanced in two of three cultivars. Dehydration and crisps production resulted in an increase of RAG, whereas in French fries, a significant decrease of RAG and a significant increase of SAG were found. Calculated data of the glycaemic index and the glycaemic load reflected comparable trends as was shown with temporal glucose release. The results for the potato cultivars tested clearly indicate the need for specific evaluations to prevent inaccuracies in case of potato rating.