Plasma Glucose and Insulin Responses to Carbohydrate Food (Rice) with Different Thermal Processing

The effects of thermal processing on plasma glucose and insulin responses in healthy subjects were examined. Fourteen volunteers, after being tested with a glucose load, were randomly administered a test meal, consisting of an amount of rice, calculated to yield the same quantity of glucose, used for the glucose tolerance test (70 g). Rice (90 g, raw) was cooked in two different manners: (a) boiled in salted water and (b) baked for 10 min at 160 °C after boiling as in the first test. A clear difference in viscosity and in in vitro hydrolytic rates between the two rice items could be established, whereas the plasma glucose and insulin responses in the volunteers differed to a smaller extent. In particular the 60-min incremental area for glucose was significantly lower in the case of baked rice, compared to boiled rice. These findings suggest that thermal processing of complex carbohydrates may differently affect glycemic responses in man.