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Process optimization and product characteristics of white kenkey (nsiho)

Oduro-Yeboah C.. 2016. Accra : University of Ghana, 339 p.. Thesis Ph.D. -- Food science.

Kenkey, is a maize based sour, stiff dumpling, and it is among the most common fermented cereal food products in Ghana. There are several types of kenkey, and while some are made from whole maize grains others are produced using degermed/and dehulled maize grains. The kenkey types made using dehulled maize grains are less popular and have largely remained at the level of ¿ethnic food¿, restricted to very few socio-cultural communities. Current trends in urbanization, and the increasing popularity of kenkey among consumers, require larger scale production with consistent quality. The study was carried out to examine the traditional white kenkey process and to optimize the key processing variables in order to obtain reproducible quality white kenkey that will be acceptable to native and non-native consumers. A survey was conducted in three white kenkey production districts to collate information on production, vending and consumption practices. The sensory profile and consumer acceptance of different types of kenkey and other fermented maize products in Ghana were investigated. A total of two hundred consumers including 110 Ghanaians and 90 internationals were used for the consumer test. Traditional white kenkey types were analyzed for their physicochemical, textural, microstructure and sensory characteristics. Physicochemical analysis involved determination of pH, titratable acidity, sugars, lactic acids, minerals, vitamins and amino acids using high performance liquid chromatography procedures. The textural characteristics of white kenkey randomly obtained from traditional processors were determined using instrumental (texture analyser) and consumer assessments. The effects of processing variables of steeping time (12, 30 and 48 h) and dough fermentation time (0, 12 and 24 h) on the physicochemical properties of white kenkey were determined. A (three variable) Box-Behnken design was used to optimize the processing variables of steeping time, steeping temperature, and fermentation time on white kenkey quality parameters of moisture, pH, titratable acidity, glucose and lactic acid content. The optimum region of the process variables was obtained by hedonic tests on the white kenkey using balanced incomplete block design (for k= 5, b= 21, ¿=2, r =7) Quantitative Descriptive Analysis (QDA) was conducted on white kenkey made from within and outside the optimum region of the process variables, as well as white kenkey obtained from vendors using a panel of 18 trained members. Consumer acceptance study was conducted using 65 consumers for white kenkey obtained from the optimum region and traditionally processed white kenkey obtained from vendors. The results of the survey showed that there were two main types of white kenkey, nonsweetened white kenkey and sweetened white kenkey to which sugar is added during production. All three procedures involved steeping of dehulled maize grains which is then milled into a meal. In the (procedure at Atimpoku), the meal was not fermented any further but precooked, moulded into balls wrapped in leaves and steamed. In the (procedure at Anum), the meal was kneaded into dough and allowed to ferment for 12hours, the fermented dough (70%) is precooked and mixed with the remaining dough, moulded into balls and steamed. Three classes of behaviours of consumers were identified. Those who liked all the products 'all likers' (36%), those who preferred the white kenkey 'white likers' (30%) and those who preferred Banku 'banku likers' (34%). Sensory attributes important for the white likers were whitish colour, fruity odour, smooth and nonsticky texture, a less sour product without a pronounced fermented odour, and a bland taste. The white kenkey samples randomly obtained from vendors contained 70 ¿ 77 % moisture, 0.58-0.88 g/100 g ash, 0.09-0.19 g/100 g fat, 2.45-2.84 g/100 g protein, vitamin B1 of 17-47 g/100 g, had pH of 4.07 ¿4.54, titratable acidity 0.42-0.60% lactic acid, 2-28 mg/g glucose, and 0.6-2 m...

Mots-clés : maïs; produit transformé; produit fermenté; technologie traditionnelle; qualité; acceptabilité; comportement du consommateur; consommation alimentaire; enquête auprès des consommateurs; technologie alimentaire; trempage; analyse organoleptique; fermentation; propriété physicochimique; composition chimique; circuit de commercialisation; commercialisation; ghana

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