Glycemic response to starch in pasta: a study of mechanisms of limited enzyme availability

Abstract

The aim of this work was to measure the availability of starch in pasta products and to study the mechanisms which affect the rate of digestion and absorption of starch in pasta. Healthy subjects were given test meals with an equivalent amount of available carbohydrate from macaroni (25/75% durum/Swedish wheat flour), spaghetti (100% durum wheat flour + monoglycerides), ‘spaghetti porridge’ (cooked spaghetti mixed in a food processor) and, for comparison, bread (made from spaghetti ingredients) or mashed potatoes. Blood glucose levels were measured over a 3 h period and glycemic indices (GI) were calculated using 90 or 120 min areas under the glucose curves. A new in vitro test was introduced to measure the rate of starch hydrolysis in products with a food form ‘as eaten’. The three pasta products produced significantly lower peak blood glucose values and lower GI (90 min) than the corresponding bread. The spaghetti also displayed a more favourable late post-prandial glucose response, with a low but sustained increment above the fasting level in the late phase. Significant differences between bread and mashed potatoes were only detected in the late phase. The ‘lente’ properties of the pasta were assigned to a restricted enzymic availability due to a more compact food texture. The importance of the food structure was further substantiated by a significant increase in GI following mixing of the spaghetti product. The in vitro method ranked the different wheat products similarly to the in vivo situation and is recommended for prediction of the glycemic response to various food items.