Browsing by Author "Ogombe, Charles Ojiambo"

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    Nutrients and Anti-Nutrients Levels, and Nutrients Bioaccessibility in Cooked Manihot Esculenta Crantz Varieties Grown in Kilifi and Busia Counties, Kenya
    (Kenyatta University, 2025-11) Ogombe, Charles Ojiambo
    Manihot esculenta Crantz (cassava) is a staple crop, with different sweet and bitter varieties grown in developing nations. Bitter cassava varieties are primarily used for industrial purposes like making flour, starch, bioethanol, and adhesives after being processed to remove toxic cyanide. Sweet cassava is used for direct food consumption, where it is boiled, fried, or baked, and it can also be processed into various food products like flour and snacks. The study areas in Kenya, Kilifi County, grow Kibandameno and Tajirika varieties while MM96/2480 and Migyera are cultivated in Busia County. The crop’s roots and leaves are a source of protein, thiamine, riboflavin, ascorbic acid, niacin, potassium, calcium, zinc, iron, oxalate and phytate. Nutritional data has shown that Kilifi and Busia Counties have high prevalence of under nutrition, amidst relying on otherwise nutritious cassava-based diets. For consumption, the general cooking methods involves roots being boiled or deep-fried, while leaves are pounded then boiled. In view of malnutrition statistics in communities that otherwise consume cassava, it is unclear whether the underlying factor would be attributed to impact that cooking has on nutritional levels of both leaves and roots of cassava, or nutrient bioaccessibility. This was envisaged as a study gap. The concentrations of specific anti-nutrient and nutrients in cassava leaves and roots with age of the plant, impact that boiling and deep-frying tubers and boiling leaves of cassava has on nutritional and anti-nutrient levels, and finally the bioaccessibility of nutrients were determined. Static gastrointestinal digestion was performed after and prior to determination of protein (by kjeldahl), vitamins and anti-nutrients (by HPLC) and minerals (by AAS and AES). Nutrient levels (mg/100 g) in raw roots ranged from 17.00 - 114.00 (protein), 1.93 - 12.74 (vitamin C), and from 32.08 - 162.98 (Ca). Levels of anti-nutrients (mg/100 g) ranged from 390.37 - 561.28 (phytate), and from 4.72 - 613.46 (oxalate). Cooking resulted in a reduction of the levels ranging from 12% (K) to 98% (vitamin B1) in all nutrients and anti-nutrients studied, with boiling roots recording higher losses than deep-frying (P<0.001). The bioaccessibility of vitamins and minerals was lower in raw roots (15 - 72%), but significantly higher (P<0.001) in cooked roots, with deep fried roots showing bioaccessibility between (20 – 79%) and boiled roots between (27 – 84%). A trend similar to the one observed in roots was observed in cooked cassava leaves with bioaccessibility ranges of vitamins in raw leaves (8 – 69%) being significantly lower (P<0.001) than in boiled leaves (11 – 81%). The study concludes that levels of ascorbic acid, thiamin, riboflavin, niacin, protein, calcium, zinc, iron and potassium, phytate and oxalate in Manihot esculenta Crantz varieties depend on the variety, part of the plant (roots or leaves), and harvesting age. Cooking significantly reduces levels of these nutrients and anti-nutrients with a higher reduction on boiling than deep-frying. The bioaccessibility of nutrients however significantly increased with cooking but the levels were lower than the recommended dietary allowance (RDA) for all the nutrients determined. The study recommends that cooking lowers anti-nutrients and increases nutrient bioaccessibility. Cassava roots should not be left in the farm for a longer period after maturity when nutrient levels are high and cooking by deep frying to retain high levels of the water-soluble nutrients