1.1 Introduction
Cocoyam (Xanthosoma sagittofolium and Colocasia esculenta) are tropical root and tuber crops largely produced for its underground corms which belongs the family Aracea family. It is grown and produced in Nigeria and in many other parts of the tropical and subtropical areas of the world ( Aboubakar et al ., 2008).
The estimated world production of cocoyam is placed at 5.5 million tonnes annually with Ghana and Nigeria being considered as the world leading producers (Sefa Dedeh and Ayir sackey, 2004).
Cocoyam corms and cormels are usually eaten boiled, roasted, pounded and sometimes mixed with other staples such as yam, cassava or plantain Ihekoronye and Ngoddy, 1985).
Cocoyam is nutritionally superior to other roots and tubers in terms of digestibility crude protein and minerals such as Ca, Mg and P (Chukwu et al., 2008). Protein and fat content of cocoyam are low but it is high in carbohydrates, fibre and minerals (Del Rosario and Lorenz, 1999).
Even though cocoyam is not an industrial crop , its starch has numerous applications for use in several food products due to its small particle size which offers improved binding and may offer additional health promoting benefit . It is widely used as soup thickener and usually pounded to a soft dough known as utara ede in south eastern Nigeria (Ihekoronye and Ngoddy, 1985).
One of the problems facing cocoyam is post harvest storage. Cocoyams can be best stored in cool dry ventilated surrounding and the best temperature for prolong storage is about 70C storage at lower temperature leads to death of buds and decay of the corns within two months while storage at higher temperature such as 15-230C is not satisfactory for long periods . In some communities in south east Nigeria, cocoyams are stored by being buried under the earth in a cool environment or swamp and this storage of cocoyams under earth in a cool dry ventilated surrounding or swamp result in the sprouting of the corms at the availability of some level of moisture (Onwueme and Charles,1994).
Sprouting is characterized by increase in enzymatic activities which results to breakdown of macromolecules and mobilization of reserves from the corm to the growing shoot. The desirable nutritional change that occur during sprouting are mainly due to the breakdown of complex compounds into a more simple form, transformation into essential constituents and breakdown of nutritionally undesirable constituents ( Chavan and Kadam, 1 989).
The thickening property of cocoyam is affected by varieties of different factors like sprouting, however, the level of its efficacy maybe influenced by some factors such as; the soil type, special type, process conditions, innate properties of the food in which it is used as an additive, in all the different ways that cocoyams are being consumed traditionally whether by boiling, pounding as a soup thickener etc. softening of the cocoyam tuber when cooked is a critical factor which is used to determine its degree of doneness (Onwueme and Charles, 1994).
Successful performance of flours as food ingredients depend the functional characteristics and sensory qualities they impart to the end product (Kaur and Singh, 2007). The functional properties of flour are provided not only by proteins, but also by the complex carbohydrates and other components such as pectins and mucilages (Kaur and Singh, 2005).
1.2 Problem Statement
Investigation showed that millions of people consume cocoyam yearly but do not sprout it, few people that does, do not know the effect, thus, this research work tend will serve to educate people more on the reason why they should sprout their cocoyam before consumption and its economic value so that the society at large will not only focus on its thickening property but also on its good materials and health benefits.
Cocoyams have a short-shelf life because of their high moisture content and start rotting as early as 2 weeks post-harvesting, thus, this research work tend to minimize tuber losses by converting them from perishable to non perishable through food processing operations and one of the best ways to preserve them is by processing them into flour and starch. Thickening power is desired as well as the small particle size in being useful for bread or noodle production.
1.3 Aim and Objectives of Study
The aim of the study is to study the effect of sprouting on the proximate composition thickening properties of two varieties of cocoyam. In achieving this aim, the following specific objectives were laid out as follows:
- To determine the proximate composition of two varieties of sprout and unsprouted cocoyam.
- To determine the thickening properties of two varieties of cocoyam.
- To know the effect of sprouting on the two varieties of cocoyam.
- To produce cocoyam flour.
- To help in promoting the utilization of sprout cocoyam and its flours.
1.4 Justification / Significance of the Study
Sprouting has been observed to improve the thickening properties of cocoyam and its utilization, sprouting equally reduces the anti-nutritional factor present in cocoyam. It also reduces the carbohydrate the carbohydrate content of cocoyam which when too much can increase the blood sugar level and finally sprouting increases fibre content of cocoyam.
The high viscosity of cocoyam starches makes them very useful in food applications where high thickening power is desired as well as the small particle size being useful for bread or noodle production (Aprianita et al., 2009).
1.5 Scope of Study
The scope of the research is focused on the Effect of Sprouting on the Proximate Composition and Thickening Properties of the Two Varieties of Cocoyam, Ede Ocha (Xanthosoma Sagittifolium) and Ede Ofe (Colocasia Esculenta).
1.6 Limitations of the Study
During the course of this study, there were some problems encountered which stood as limitations to the research work. Some of the limitations include:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
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