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
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Date
APRIL, 2015.
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Abstract
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
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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.
Description
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.