Effect of different processing methods and periods of storage in different containers on some quality characteritics of kernel and extracted butter of shea nut

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April 2015
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Shea kernel processing methods and storage are some of the major challenges leading to low quality kernels and shea butter production in Ghana. In this study, fresh shea fruits were collected at Cocoa Research Institute of Ghana substation Bole in Northern Region of Ghana. The fruits were depulped on the same day and nuts washed and divided into two parts. One part was parboiled at 40 o C for 20 minutes while the other part was not parboiled before putting them into solar driers for drying. Shea kernels were removed from the nuts and dried in solar driers until they attained a moisture content of 7%. Kernel samples were then put into five different storage containers (jute sack, cardboard, polyethylene bag, synthetic fibre and plastic bucket) and stored for seven months. Carbohydrate and crude protein contents were significantly (p<0.05) higher but ash content lower in parboiled kernel than non-parboiled. Fat, energy, nitrogen free extract, moisture and crude fibre contents were not different among kernel samples at p=0.05. Free fatty acids profile levels were significantly (p<0.05) higher in non-parboiled shea kernel than the parboiled while peroxide value was higher in parboiled kernel. Aspegillus niger was identified on both parboiled and non-parboiled kernel samples but percentage infection was not significantly different (p>0.05). There were significant differences (p<0.05) in shea kernels proximate and chemical constituents at seven (7) months storage. Shea butter obtained from the parboiled and non-parboiled kernels were distinctively different from each other in colour, taste and smell. Storage containers did not significantly (p>0.05) affect kernel proximate and physico -chemical characteristics of the butter except moisture content that kernels kept in polythene bag were higher than those kept in the cardboard. Parboiling of fresh shea nuts before drying and storage period are key determinants of kernel proximate composition and physico-chemical properties of the butter.
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 Masters Of Philosophy In Post Harvest Technology, 2015