1.1 Background of the study
Cassava Plant (Manihotesculenta) belong to the family of Euphorbiaceae(Spurge family).It is a higher producer of carbohydrate per hectare than the main cereal crops and can be grown at a considerably lower cost. It also grows at a suboptimal condition;it is tolerant of soil infertility and drought stress and can be stored underground for several months after maturation (Onabolu and Vlavono.,1988).Cassava is often referred to as a food security crop because of several reasons;firstly, the planting and harvesting time is flexible, which allows it to be harvested when really needed; secondly, because of the tolerance towards low soil fertility and water availability; and thirdly, the plants can be multiplied by vegetative propagation without the need for seeds, allowing farmers to continue to grow the crop without financial input. Cassava cultivation has increased over the past three decades in Eastern Africa due to increasing land pressure by population growth and also due to providing income to farmers. It is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, is a major source of carbohydrates.(Alves,2002) defined cassava root as a draught tolerant crop that grows well in poor soils and marginal lands. The roots are very rich in starch and contain significant amount of calcium (50 mg/100g),phosphorus (40 mg/100g)and vitamin C (25 mg/100g).Cassava roots is normally processed before consumption as a means of detoxification, preservation and modification. In Nigeria, cassava rootsareprocessed into various products such as;garri, fufu, lafun, pellets for compounding animal feeds, and also into instant aromatized (fermented) flour (Oyewole,1991).
Lafun is a fermented cassava flour, popularly consumed in south west Nigeria. It is generally prepared into a thick paste in boiling water and eaten with vegetable soup or stew. But it is processed from cassava by peeling, cutting, submerged fermentation, dewatering, sun-drying and milling to produce ‘lafun’ flour (Oyewole and Sanni,1995). Lafunpowder is a dry product, which can be preserved for a long time under the prevailing local environment.(Eleazuet al., 2011) viewedfermentation as the process during which several anaerobic and catabolic reaction occur simultaneously depending on some factors such as substrate, micro flora and environmental factors. During fermentation, cassava tissue is softened and disintegration of the tissue by microorganism result in contact of cyanoganicglucosides, linamarase located in the cell wall (Makporyet al., 1990). Cassava fermentation occur in two form which are the aerobic fermentation (heap fermentation) and anaerobic fermentation(Hahn1992).Heap fermentation involves surface drying the roots, 1 to 2 hours after which they are heaped together, covered with leaves or straws and left to ferment 3 to 4 days until the pieces become moldy after which they are scraped sun dried and milled to flour. The second method is anaerobic fermentation in which grated cassava tubers is placed in sacks and pressed with stones or a jack between two plat-form (Hahn et al., 1987).For lafunproduction in Nigeria, peeled or unpeeled cassava tubers are immersed in a stream, in stationary water (near a stream) or in an earthenware vessel, and fermented until the roots become softs. The peel and the central fibres of the fermented roots are manually removed and the recovered pulp is hand mashed or pounded.
Cassava as a staple crop has advantageous agronomic qualities, but contains low amounts of micronutrients such as Vitamin A. Lafunbeing a fermented product from cassava also lacks these micronutrients.According to (Pamela and Champe, 1994;Robert et al., 1993), vitamins are essential food receptors which are important for the proper utilization of the proximate principles of foods such as carbohydrates, proteins and fats in addition to the maintenance of good health in humans and experimental animals. (Astorg,1997; Olson,1999), stated that carotenoids are compounds found in plants that can enhance the human health immune response and reduce the risk of degenerative diseases such as cancer, cardiovascular diseases, cataracts, etc. and these have been attributed to their antioxidant property, specifically, their ability to quench singlet oxygen and interact with free radicals.Studies have indicated a significant reduction in maternal mortality and postpartum infection with either vitamin A or β-carotene supplementation.This has thus necessitated the need for supply of foods that contain significant quantities of carotenoids especially for young children or the fortification of existing foods to meet the vitamin A requirement.
Over the years, breeders have developed new and improved varieties of cassava that have been distributed to and promoted among local farmers in sub-Saharan and South American countries (Acheamong, 2015). These varieties have improved characteristics or traits such as improved yield, improved micronutrient content (i.e. bio-fortifiedcassava e.g. Yellow cassava), etc.Yellow cassava is similar to white varieties of cassava but it has a yellow flesh inside the root, which is generally white in the white varieties.Like the white cassava, it does not need nutrient rich soils or extensive land preparation and does not suffer during droughts.Yellow cassava contains high levels of β-carotene, which is a precursor to vitamin A. Cassava is also a major source of carbohydrates, 80% of which are starches. Yellow cassava can provide up to 25% of daily recommended Vitamin A intake. Since cassava is a major part of many people’s diets, cassava bio-fortified with Vitamin A is an excellent innovation to improve health on a large scale. (Bai et al., 2010; Sagar et al., 2009; Omodamiroet al., 2011), studied the effects of processing on the retention of carotenoids in yellow cassava. (Akingbalaet al., 1991), stated that processing has effects on the nutrient content of food. Since human health is generally determined majorly by things consumed as food. It is of importance in this research to know the effects of fermentation on the physiochemical and sensory properties of lafun made from yellow cassava that is beneficial to human life.Research has suggested that vitamin A supplementation in the form of two high dosesper year proved to reduce mortality by 24%.
1.1Justification of the Study
Cassava bio fortified with micro nutrients could be a sustainable approach to control micro-nutrient and alleviate malnutrition (Bouiset al.,2011).Vitamin A remains a very important component of human nutrition as it is involved in vision, cell differentiation,synthesis of glycoproteins, reproduction and overall growth and development (Woolfe, 1992). African countries arenot only faced with problem of food security but that of nutritional insecurity leading to different forms ofmicronutrients deficiencies in the diet.Bio-fortification of cassava is therefore highly appropriate as this will contribute to the alleviation of diseases associated with vitamin A deficiency (VAD) which is a common dietary health problem, especially in countries where cassava is a major staple.
Previous works have been carried out on the use of yellow cassava root with promising results. Thus, this study is to further enhance its use as a raw-material for lafun production.
1.2 Objective of the Study
The generalobjective of this study was to evaluate the effect of fermentation on the physiochemical and sensory properties of lafun made from yellow cassava
The Specific objectives
- To determine physico-chemical characteristics of lafun made from yellow cassava
- To examine the effect of fermentation on the sensory properties of lafun made from yellow cassava.
- To assess the sensory evaluation of cooked lafun
- To determine the nutritional quality of lafun made from yellow cassava.
- To determine the functional property of lafun produced from yellow cassava
- To determine the shelf life and storability of yellow cassava flour