Ghana in recent times has witnessed increasing awareness of the dietary intake of the ordinary Ghanaian and its effect on his health status. Despite this awareness, however, Biritwum et al. (2005) reports that the country is still faced with continued rise in the prevalence of obesity alongside high levels of diet related health conditions. Enough evidence notable in speeches of most health practitioners points out that substantial changes in our diet at the micro-level would decrease the reported cases of various health related conditions such as cardiovascular disease, diabetes and cancer, as well as obesity.
Since a change in the diet of a population is difficult and often requires a shift in the food habit of the people, small changes in the intake of various nutrients from mixed food sources may confer health benefits that may possibly improve the nutritional status of most Ghanaians.
The prevalence of obesity and the high level of diet related health conditions have generated a lot of concern about our dietary intake and its effect on our health. The need to make more informed choices regarding food preferences among the Ghanaian folks cannot be overemphasized. In the light of these problems, the tiger nut has been recognized as one of the best nutritional crops that can be used to augment the diet (Afenu, 2008). The tiger nut crop is one of the cash crops, which is not given due recognition and patronage possibly because many people do not know its nutritional benefits.
Tiger nut, (Cyperus esculentus I.), is a vigorous plant with leafs in rosette and measures from 40-50 centimeters. It possesses a rhizomatic radicular system, from which depart small roots in which extremes the tiger nuts are formed. The tiger nuts acquire two forms: "largueta" (prolonged) and "armela" (rounded). Initially, the root crop produces leaves and flourishes as plants do but as the days become shorter and cooler, leaf production will cease and tubers will be formed. High temperatures and low nitrogen levels increase tuber production.
Tiger nuts, according to Abodunrin and Belewu (2008) was found to be a good substitute for cereal grains. The nut which is cultivated throughout the world are also found in the Northern part of Nigeria and other West African Countries like Guinea, Cote divore, Cameroon, Senegal, America and other parts of the world (Irvine, 1969 in Abodunrin and Belewu, 2008). The nuts are valued for their highly nutritious starch content, dietary fibre and carbohydrate. The nut is reported to be rich in sucrose (17.4-20.0%), fat (25.50%) and protein (8%) (Kordyias, 1990 in Abodunrin and Belewu, 2008) The nut is also rich in mineral content (sodium, calcium, potassium, magnesium, zinc and traces of copper (Omode et al., 1995, in Abodunrin and Belewu, 2008).
The tiger-nut crop has been found to be a healthy tuber with a high content of oleic acid, positive effects on cholesterol levels and high content of Vitamin E. It is highly recommended for diabetics, children, older persons and sportsmen. This study was conducted to extract and formulate milk from roasted and non-roasted tiger nut into palatable beverage and to evaluate the qualities and consumer acceptability of these beverages.
MATERIALS AND METHODS
Fresh tiger nuts were purchased from the Kotokuraba market in Cape Coast, Central
region of Ghana. Preparation of the tiger nut milk was done by picking out those
foreign and bad nuts that could affect the taste and keeping quality of the
beverage. Two preparations were made from non roasted tiger nuts and roasted
tiger nut. For the preparation of tiger nuts milk from the non roasted, the
nuts were soaked overnight for approximately 12 h after which it was washed
thoroughly and blended by adding 600 ml of water to 400 g of tiger nut. It was
then filtered using muslin cloth applying pressure to the content to achieve
maximum liquid extraction. The filtrate was put into a clean double bottomed
saucepan and brought to the boil. It was then allowed to simmer for between
15 and 20 min to avoid curdling and then allowed to cool. Figures
1a and 1b shows the flow chart for the preparation of
the tiger nut milk. The cooled filtrate was poured into a sterilized bottle
and further sterilized. It was then allowed to cool and refrigerated. For the
preparation of the milk from the roasted tiger nuts, the nuts were roasted for
approximately 15 min and then the process for the non roasted followed.
Forty untrained panelists from Cape Coast comprising both males and females were used in the sensory evaluation study. The panelists reflected the range of preferences likely to be typical of ethnic consumers. Panelists were presented with the two samples, the roasted and non-roasted tiger nuts. Panelists were asked to compare the two samples on the bases of mouth feel, texture, taste, aroma, consistency, appearance and general acceptability, using the hedonic descriptive scale 1-5 (Table 1). Assessors were instructed in the basic taste panel procedures, to make their own individual judgments after a moderate amount of consideration. The panelists were instructed to take a sip of water and pause for a few seconds before tasting each sample and to re-taste if they were not sure of their decisions.
From the data obtained, the mean values and standard error for each was calculated. The significant differences between the samples were tested using the t-test.
RESULTS AND DISCUSSION
Table 2 demonstrates the percentage score on comparative sensory evaluation of the roasted and non-roasted tiger nut samples used in this work.
The mouth feel of tiger nut beverage is an important factor for consumers. Of the 40 panelists who participated in the sensory evaluation 95% indicated their acceptance of the mouth feel of the non-roasted tiger nut beverage while 85% accepted the roasted tiger nut beverage. Thus, there is a slight preference for the non-roasted tiger nuts. This is confirmed by the mean values (Table 3) which are not significantly different at the 1% level.
The texture quality is also an important factor to consumers. Of the 40 panelists, 88 % accepted the texture of the non-roasted tiger nut beverage while 87 % indicated their acceptance for the roasted tiger nut beverage. There is no significant difference between the averages.
The aroma of a beverage is important to the consumer. The panelists
were therefore asked to compare the aroma of the roasted tiger nut beverage
and the non-tiger nut beverage. 85% of the panelists indicated their acceptance
of the two beverages.
chart for the preparation of non-roasted tiger nut beverage
chat for the preparation of roasted tiger nut beverage
scoring for assessment of consumer acceptability of tiger nut beverages
score on comparative sensory evaluation of roasted and non-roasted tiger
The taste of the beverage is also an important feature for consumers. Of the
40 panelists, 95 % accepted the taste of the non-roasted tiger nut beverage
while 87% accepted the taste of the roasted tiger nut beverage. The results
indicate that although there is a general acceptance for the two beverages,
there is a slight preference for the non-roasted tiger-nut beverage.
The consistency of the beverage, that is how light or heavy the beverage is, is an important factor for the consumer. 13% of the 40 panelists expressed their reservations about the consistency of the non-roasted tiger nut beverage compared to 87% who accepted it as good. 92% of the panelists accepted the consistency of the roasted tiger nut beverage.
The appearance is important to consumers. The panelists thus compared the appearance of the non-roasted tiger nut beverage with that of the roasted tiger nut beverage. 98% of the panelists accepted the appearance of the non-roasted tiger nut beverage as good while 93% accepted the roasted nut beverage as good. There was insignificant difference between the mean values of the two beverages.
The general acceptability of the beverage is very important to the consumers. 98% of the panelists found the roasted tiger-nut beverage very acceptable while 90% of the panelists found the non-roasted nut beverage very acceptable. There seem to be a slight preference for the roasted tiger nut beverage.
Correlation analysis of the results showed that although the texture, aroma, appearance and consistency were important for consumers, mouth feel and taste were more important for the overall acceptance of the beverages. The mouth feel of the non-roasted tiger nut beverage was more acceptable than the mouth feel of the roasted tiger nut beverage. Also the taste of the roasted tiger nut was more acceptable to the panelists than that of the non-roasted tiger nut beverage.
Conclusion: In summary, the sensory evaluation study of roasted and non-roasted tiger nut beverages revealed that although the texture, aroma, appearance and consistency were important for consumers, mouth feel and taste were more important for the overall acceptance of the beverages. The mouth feel of the non-roasted tiger nut beverage was more acceptable than the mouth feel of the roasted tiger nut beverage. Also the taste of the roasted tiger nut was more acceptable to the panelists than that of the non-roasted tiger nut beverage. General preference, however, is given to the roasted tiger nut beverage.
The author is grateful to Professor R.K. Nkum, the Rector of this Polytechnic, for reading the manuscript and offering many useful suggestions.