EFFECT OF CHILLING TEMPERATURE ON THE DIGESTIBILITY OF CASSAVA STARCH

EFFECT OF CHILLING TEMPERATURE ON THE DIGESTIBILITY OF CASSAVA STARCH
 
CHAPTER ONE
INTRODUCTION
1.1       Background of the Study
Cassava (Manihot esculenta, Crantz), also called, manioc, tapioca or yucca, is one of  the most important food crops in the humid tropics, being particularly suited to  conditions of low nutrient availability and able to survive drought. it is a dicotyledonous plant, belonging to the family Euphorbiaceae (Alves, 2002). It is a perennial shrub, 2 to 4 min height and is mainly propagated from stem cuttings. It is a widely grown crop in most countries in the tropical regions of Africa, Latin America and Asia; and ranks as one of the main crops in the tropical countries.
Cassava is grown over a range of climates and altitudes and on a wide variety of soils. Cassava is tolerant to drought and is productive in poor soil where other staple crops cannot grow (Bradbury and Holloway, 1988).
Among the starchy staples, cassava gives a carbohydrate production which is about 40% higher than rice and 25% more than maize, with the result that cassava is the  cheapestsource of calories for both human nutrition and animal feeding. More thantwo-third of the total production of cassava is used as food for humans, with lesser amounts being used for animal feed and industrial purposes. Nigeria alone currently produces over 14 million tons annually, representing about 25% of sub-Saharan Africa’s output.
Although cassava is the third most important food source in the tropical world after  rice and maize, and provides calories for over 160 million people of Africa, its food value is greatly compromised by the endogenous presence of cyanogenic glucosides.
The ability of the crop to survive during drought makes it one of the easiest crops that can be cultivated even when rainfall is not regular. It is reported that over 500million people around the world derive their daily carbohydrate intake from cassava (Udofia et al.,2010). There are two major issues in the utilization of cassava; first, cassava root is highly perishable and cannot be stored in fresh form for more than 3 days after harvesting. Physiological deterioration of the root occurs in 2 -3 days after harvesting follow by microbial deterioration in 3 –5 days (Akingbala et al.,2005).
However, the study tends to examine the effect of chilling temperature on the digestibility of cassava starch.