Process Optimization And Product Characteristics Of White Kenkey (Nsiho)

ABSTRACT

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

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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, λ=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

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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 mg/g lactic acid. The amino acids lysine, methionine, Gaba and

Ornitine values were less than 0.2 g/100g. Steeping time of maize was complimentary to

fermentation time since both influenced the conversion of glucose by lactic acid bacteria

into lactic acid. Generally, the longer steeping and fermentation times gave higher levels of

glucose and lactic acid in the white kenkey. However, whilst steeping increased glucose

level, dough fermentation reduced it. The intensity of whiteness (L) in white kenkey

diminished as steeping time increased. On the other hand, fermentation time improved

whiteness of kenkey. High aflata (i.e ratio of precooked to uncooked dough) produced

kenkey with softer texture, whilst reducing the aflata ratio increased the hardness and

stickiness of white kenkey. Consumers preferred white kenkey made using high aflata ratio

and steamed for longer periods.

The optimization studies showed that processing variables had significant effects on the

physicochemical and sensory characteristics of white kenkey. The optimum region for the

process variables at which the most acceptable kenkey was obtained were steeping time of

30-45 h at 30-35ºC temperature followed by 12 h dough fermentation. Consumer

acceptance test indicated no significant difference in acceptance between the traditionally

processed white kenkey samples and those obtained from the optimum region. White

kenkey samples of higher quality potential has been identified. The process for production

of white kenkey has been standardized, saving production time.