Effect of variety and processing methods (holding period and drying method) on quality of cassava flour (Kokonte) in the Hohoe Municipality of the Volta region of Ghana

A thesis submitted to The School of Research And Graduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the award of a Master of Philosophy in Postharvest Technology.

The study was undertaken to identify the „Kotonte‟ methods prevailing in the Hohoe Municipality of the Volta region of Ghana leading to improvement in the product quality. Samples processed from two varieties, namely Ankra and Afisiafi held in temporary storage containers for 0, 2, 4 and 6 hours and subjected to sun and solar drying were analysed for sensory qualities using a preference test. Twenty one (21) untrained judges or consumers from the study area were asked to observe, feel, smell, taste and indicate how much they liked or disliked each sample based on 7 point hedonic scale. The survey results showed that all the „Kokonte‟ producers in the study area used or depended solely on sun drying to dry their fresh cassava chips. Majority (90%) of the producers processed cassava from their own farms into „kokonte‟ while the minority (10%) depended on the cassava sold in some major markets as sources of raw material for the processing which is clear indication that the „Kokonte‟ business in the area is sustainable. The results also showed that varietal differences did not affect the sensory qualities significantly. However, there were significant differences in their protein and carbohydrate contents. Afisiafi had higher protein content (1.4%) as compared to Ankra (1.3%). On the other hand, Ankra had significantly higher carbohydrate content (84.3%) than Afisiafi (84.1%). There were also significant varietal differences in the pasting temperatures and breakdown in viscosity but not peak viscosity and setback of the sample flours when cooked. Ankra recorded the higher pasting temperature (71.0ºC) over Afisiafi (68.3ºC). Ankra also recorded the higher breakdown indicating low product stability. The difference in drying method (solar dryer and sun drying) did not record any significant variation among the sensory properties (aroma, taste, colour and texture). Also, contrary to expectation, there was no significant difference recorded in protein content due to difference in vi drying methods employed. However, sun drying retained significantly higher carbohydrate content (84.3%) than solar dryer (84.2%). Drying method affected only the breakdown and setback significantly. Sample held for 4hours recorded the higher carbohydrate content of 84.3% as compared to zero hour hold (84.2%).With regards to pasting temperature, peak viscosity, breakdown and setback 6hour hold recorded the highest pasting temperature (71.1ºC) which is associated with higher cost of fuel and energy as compared to 2hours hold (68.5ºC). Zero period of hold recorded the highest peak viscosity (539.8BU) as against 6hours of hold (481.6BU). Highest breakdown was recorded by zero hour of hold with 263BU as compared to 207.5BU of 6hours of hold. Setback was highest in 6hours hold (8.8BU) and least in zero hour holds (4.6BU). It was discovered that the solar dryer took three more days to dry the „Kokonte‟ chips completely as compared to sun drying due the unventilated nature of it which could lead to rapid mold growth. Since consumers perceived the sensory attributes equally but possible mold growth, ease break down in viscosity of product at high temperatures, delay in drying process and relatively high cost of drying associated with the solar dryer, sun drying method was better. In terms of variety, Afisiafi is of better quality than Ankra. In all, „Kokonte‟ business in the study area had good prospect and hence sustainable.

KNUST