The Effect of Storage Period on the Proximate and Functional Composition of Soy-garri at Different Storage Periods
Chapter One
The Objective of the Study
This project work, therefore, seeks to investigate the effect of the storage period on the proximate and functional properties of soya-garri. It also evaluates the consumer acceptability of the product after a period of time.
CHAPTER TWO
LITERATURE REVIEW
Cassava (Manihot esculenta Crantz)
Cassava (Manihot esculenta Crantz) is the most perishable of roots and tubers and can deteriorate within two or three days after harvesting. It is one of the most important staple food crops grown in the tropical Africa, and plays a major role in effort to alleviate African food crisis because of its efficient production of food energy, year-round availability, tolerance to extreme stress conditions, and suitability to present farming and food system in Africa (Cardoso et al., 2005).
Taxonomy and Classification of Cassava
There is a wide range of cassava varieties which constitute the sweet and bitter cassava varieties. The designation of bitter and sweet varieties depends on taste that is associated with the levels of cyanogenic glucosides mainly linamarin. The bitter cassava (Manihot utilissima) has high level of hydrogen cyanide, evenly distributed through the root, which can amount up to 250mg/kg fresh root. It is easily recognized first by its green leaf-stalk and the whitish outer cortical layer of the root (Sirtunga et al., 2004). It also has a vegetation period of 12-18 months.
The sweet cassava (Manihot palmata) is known by a red leaf stalk and purplish outer cortical layer. In the sweet cassava, the hydrocyanic acid is confined to the skin and outerlayer of the root. Its vegetation period is relatively short usually between 6-9 months (Dulcer et al., 2008).
History and Economic Impact of Cassava
Cassava (Manihot esculenta Crantz) originated in the Northeast Brazil and Paraguay, and was later assimilated by the West Indians (Cardoso et al., 2005). Having begun with these regions, cassava is now cultivated in all tropical regions of the world among which Nigeria is one of them. Nigeria’s cassava production is by far the largest in the world, three times more than the production in Brazil and almost double the production in Indonesia and Thailand (FAO, 2006). In 2002, the Food and Agricultural Organization of the United Nation in Rome estimated cassava production in Nigeria to be approximately 34million tonnes which on comparison with other crops ranks first, followed by yam production 27million tonnes, sorghum 7million tonnes, millet 6million tonnes and rice 5million tonnes (FAO, 2006). In Nigeria, cassava appears to be the major staple food that matches the population growth. It is a major source of dietary energy for low-income consumers. It also plays a role in providing a stable food base in areas prone to drought and famine.
Cassava is predominantly used as food with small amount in agro-allied industrial livestock feed and starch production (Sanni, 2005). Many traditional foods are processed from cassava roots among which are; flour, dried chips, garri, fufu, farinha, etc. Cassava starch is extensively utilized by most of the food industries to produce; baked products, confectioneries, canned fruits, jam, preserves, monosodium glutamate (MSG), production of commercial caramel, glucose, dextrose, dried yeast, etc. Non-food uses of cassava starch include; corrugated cardboard, remoistening gum, wall paper industry, textile industry and wood furniture (Moorthy, 2005). Harvesting and transporting of roots from farm to homestead and subsequent processing are mainly done by women. Most of the steps in processing are carried out manually using simple and inexpensive tools and equipment that are available to small farmers. Cassava processing is labour intensive and productivity is usually very low. Transport of products to markets is made difficult by the poor condition of rural roads. The drudgery associated with traditional processing is enormous and the products from traditional processing methods are often contaminated with undesirable extraneous matter. Some of the products are therefore not hygienic and so are of poor market value. Better processing methods can improve the life-styles and health of rural people through higher processing efficiency, labour saving and reduced drudgery, all of which improve the quality of products.
Nutritional Value of Cassava
Nutritionally, cassava is one of the principal sources of calorie to human diet, and contributes a nominal quantity of protein and fat. Among the minerals in the tuber, phosphorous and iron predominate with nutritionally significant amount of calcium (33mg per 100g fresh weight). The tuber is relatively rich in vitamin C (35mg per 100g fresh weight), and contain traces of niacin, thiamine, riboflavin and vitamin A. The protein of the cassava tuber is rich in arginine, but low in methionine, lysine, tryptophan, phenylalanine and tyrosine. As such, protein in cassava is not only low in quantity, but also poor in quality (Delange et al., 2004). In fact an unbalanced diet containing only cassava can lead to nutritional deficiency.
CHAPTER THREE
MATERIALS AND METHODS
Materials
Dried soybean (Glycine max) and cassava (Manihot esculenta crantz) used for this research were sourced from Obada market in Emure-ile, Owo Local Government Area State, Nigeria. While the water bath (Model HH-6), centrifuged, hot air and other requirement used for this research were from the Food Chemistry Laboratory of the Department of Food Science and Technology, Rufus Giwa Polytechnic, Owo, Ondo State.
Methods
Preparation of Soybean Flour
The soybean seeds were sorted and cleaned, the soybean seed was roasted in a large pan until golden brown was obtain. Then, it was poured into a mortar and pestle to remove the seed coat. It was poured into a large tray so as to blow off the shaft; it was allowed to cooled and dry milling into powder form and sieved to package.
CHAPTER FOUR
RESULT AND DISCUSSION
Result
CHAPTER FIVE
CONCLUSION AND RECOMMENDATION
Conclusion
Supplementation reduces the swelling index, and water absorption capacity of garri. However, there were no significant difference in swelling index and water absorption capacities during period of storage for both supplement and control sample. The least gelation concentration were found to significant increases for both samples for the period of storage while the bulk densities were within the same range for the period of storage. It can therefore be considered that as storage time increases more garri will be needed to make volume of reconstituted meal “eba” especially for the supplemented garri. This study has also revealed that inclusion of soybean has greatly increased he level of proximate composition of soy-garri. This continuous dependence on “garri” without enrichment with meat, fish and other protein-rich sources would result in protein deficiency.
Therefore, the result of this work has shown the garri produced from cassava and soybean had improved protein content and ash probably the level the level of the mineral composition. Therefore soy-garri can be stored for a period of time, however, not for a very long time as increase in fat content denotes occurrence of spoilage (rancidity).
Recommendations
The study showed that garri enriched with roasted soybean most not be stored for very long period unlike that of be traditional garri since the swelling index and water absorption capacity decreased with increase in storage period. However, supplementation has been finding as a measure to increase nutritional composition of garri by many researchers. Furthermore, I recommend that further studies should be carried on microbiological analysis over a period of time to ascertain its storability.
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