Development of a rapid assessment method for the prediction of the glycemic index

The glycemic index (GI) is a measurement used to classify foods according to their potential for raising blood glucose levels. The GI of a foodstuff is generally measured by determining the increment in blood glucose concentration after the consumption of a test meal over a set period of time and comparing it with an isoglucosidic control meal (normally white bread or glucose) and expressed as a percentage within a group of individuals (in vitro). Rapid analysis methods (in vivo) have been evaluated worldwide, and in many cases these values have correlated with the GI values determined by in vitro methods. Rapid analysis methods are criticised for not providing numerical GI values, although proposed labelling legislation in South Africa recommends that suppliers should indicate only if the product has a high, intermediate or low GI. The purpose of this study was to investigate existing rapid assessment methods for the prediction of GI, and to develop a method for South Africa to be used by food producers in line with the newly proposed national labelling requirements. The preliminary studies on the developed rapid assessment method indicated good repeatability (CV 0.78%), reproducibility and precision (CV 3.5%), with accurate prediction of a foodʹs GI category as high, intermediate or low.