Determination of the glycemic index of local staples in Ghana and the effect of processing on them

Thumbnail Image
Journal Title
Journal ISSN
Volume Title
Glycemic index measures the blood glucose raising ability of foods. It is a measure of the quality of a carbohydrate food. Current knowledge on the effect of carbohydrates on diabetes and other metabolic diseases has increased concerns on carbohydrate quality and factors that affect it. The aim of the study was to determine the glycemic index (GI) of some carbohydrate-rich Ghanaian staple foods and to assess the influence of processing on the GI of foods. The study was a crossover trial involving 10 apparently healthy individuals served with 50g portions of pure glucose on two different occasions. They were subsequently given measured amounts of the test foods containing 50g available carbohydrates. The GI values were determined by measuring the capillary blood glucose levels of the subjects at fasting and after ingestion of the glucose and test foods within a 2-hour period. Sampling started 15 min after consumption and subsequent samples taken at the 30, 45, 60, 90 and 120min. A glucose response curve was drawn for each subject for both reference food and test foods. The GI of the test foods were calculated by dividing the incremental area under the glucose response curve of the test food by the incremental area under glucose response curve for the reference food and multiplying the result by 100.The glycemic responses to four major Ghanaian staples, Banku, Tuo Zaafi, Fufu (Pounded and Industry processed), Ga Kenkey were determined in ten apparently healthy individuals (8 males and 2 female) with mean age, Body Mass Index (BMI) and Waist Circumference (WC) of 30.9±6.4 years, 26.94±5.2 kg/m2 and 88.6±13.8 cm respectively. Fufu prepared from industry processed fufu flour had the least glycemic response followed by Ga Kenkey and locally pounded fufu all falling within the Low GI category. Tuo Zaafi had a medium GI and Banku had a moderately high GI. A multiple comparison of GI of the various foods by ANOVA revealed a significant difference between the GI of locally pounded fufu (LPF) and fufu prepared from industrially-processed fufu flour (IPF) (p = 0.026) implying that the processing influenced glycemic quality. In conclusion, the glycemic response of commonly consumed Ghanaian staples Banku, TZ, Kenkey, industrially-processed fufu (Neat® Fufu) and locally pounded Fufu were determined, and should guide health professionals and Ghanaians in their choices of local staples and meal planning. It is recommended that a study to determine the complete nutritional profile of the various local foods be made alongside their serving sizes to aid in the determination of glycemic load of these foods.
A thesis submitted to the Department of Biochemistry and Biotechnology, College of Science in partial fulfillment of the requirements for the degree of Master of Philosophy in Human Nutrition and Dietetics.