Influence of Processing Methods on the Glycaemic Index of Cassava-Based Traditional Foods

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November, 2018.
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Processing operations affect starch hydrolysis, digestibility, absorption and glycaemic index (GI) of food. Although some studies have reported on the effect of boiling, frying, roasting and baking on glycaemic index of traditional staples. There is limited information on the contribution of drying, fermentation, boiling and steaming on starch bioavailability and glycaemic index. This research work aimed at determining the effect of fermentation, steaming, boiling and drying on starch bioavailability and predicted GI of some cassava-based traditional foods consumed in Ghana. The total starch, amylose, amylopectin, dietary fibre and predicted glycaemic index of the intermediate and finished products were determined according to standard protocols. This research has revealed the predicted GI of cassava (47.75%), ampesi (77.30%), akyeke (79.05%), cooked kokonte with sun dried flour (40.20%) and cooked kokonte with solar dried flour (61.11%). The dietary fibre content of Capevars bankye flour was found to be 1.631% and 1.214% for sun and solar drying processes respectively. The analysis established that steaming and boiling increase GI of foods, fermentation has no significant influence on predicted GI of fermented steamed products, and drying has no substantial effect on predicted GI of cassava flour. However, staples or products prepared from solar dried cassava flour would have higher predicted GIs than those of sun dried cassava flour. This work has also provided evidence in support of the fact that starch, amylose, amylopectin and dietary fibre content of a food affect the glycaemic index of the food.
A thesis submitted to the Department of Food Science and Technology, College of Science in partial fulfilment of the requirements for the degree of Master of Philosophy in Food Science and Technology.