Steve R. A. Adewusi

Nutrient content of young cassava leaves and assessment of their acceptance as a green vegetable in Nigeria

Cassava (Manihot esculenta Crantz) leaves contained a high level of crude protein (29.3–32.4% dry weight) compared to a conventional vegetable,Amaranthus (19.6%). Ash was 4.6–6.4% in cassava leaf samples but 13.1% dry weight inAmaranthus. Dietary fibre was very high in all samples (26.9–39% dry weight) while HCN-potential was low (5.1–12.6 mg/100 g dry weight). Tannin was the highest in IITA red cassava leaves (29.7 mg/g) and the lowest inAmaranthus vegetable. In vitro digestibility was very low in oven dried samples (15.6–22.7%). Blanching increased protein content (exceptAmaranthus) and in vitro protein digestibility but decreased ash, minerals, dietary fibre and tannin, while HCN-potential was unchanged. Grinding reduced both HCN-potential and tannin by 84 and 71% respectively while oven drying only reduced the HCN content marginally. Preference studies showed that the highest percentage of respondents (25.3%) preferredAmaranthus vegetable, followed by Celosia (17.5%), Talinum (12.4%), garden egg (11.5%), with cassava leaves as the least (0.5%). Organoleptic evaluation rated cassava leaf soup inferior toAmaranthus in terms of appearance, colour and texture but equal in terms of taste and flavour and overall acceptability.

The effect of processing on total organic acids content and mineral availability of simulated cassava-vegetable diets

Changes in pH, titratable acidity and mineral content (Ca, Fe, Mg, Zn) were estimated in processed cassava products while the mineral content of raw and blanched amaranthus vegetable was determined. pH of fresh cassava (6.5) decreased as total organic acid (0.07%) increased with fermentation period. Fufu and lafun had the lowest pH and the highest total organic acids contents. Fermentation of cassava increased the total calcium and iron contents, reduced magnesium level while zinc remained fairly constant in grated cassava but was reduced when soaked in water (for the preparation of fufu and lafun). Fermentation also increased the availability of these selected minerals in both cassva products and simulated cassava-vegetable diets. Blanching reduced the mineral content of amaranthus vegetable but increased mineral availability. Fermentation of cassava and blanching of vegetables play an important role in making minerals more available and these processing methods should be encouraged to potentially ameliorate the disease states associated with mineral deficiency.

Cassava processing, consumption, and cyanide toxicity

The frequency of cassava consumption was investigated among three groups of people representing students from traditional and nontraditional cassava-consuming environments and cassava processors. Of these, 64% of the students at Obafemi Awolowo University, Ile-Ife, 38% of those at the Federal University of Technology, Akure, and 44% of the cassava processors consumed cassava products at least once a day, while 4, 35, and 28% of the groups, respectively, were moderate consumers (4-6 times a week). The serum thiocyanate level of the processors was significantly higher (0.57 mg/dl) than those of the students (0.38 mg/dl), but there was no significant difference in the urinary thiocyanate level of the three groups. Analysis of cassava and its intermediate and final products for free cyanide, acetone cyanohydrin, and intact glucosides during the production of such cassava products as gari, fufu, and lafun revealed that while the finished products might be safe for human consumption, the workers were probably exposed at different stages of processing to nondietary sources of cyanide.

Chemical composition of Acacia colei and Acacia tumida seeds—potential food sources in the semi-arid tropics

The seeds of Acacia colei (Maslin and Thomson) and A. tumida (F. Muell ex Benth.) are traditional foods of Australian Aboriginal people. Chemical analysis was carried out on seeds of A. colei trees growing in Maradi district, Niger Republic and A. tumida from a natural stand near Kunanurra in north western Australia. Crude protein (N × 6.25) ranged from 23.4% for whole A. colei seed to 30.6% for a water-processed A. colei sample and 20.4% for A. tumida. True proteins were 19.9, 25 and 18.5% and ether extracts 10.9, 18.9 and 8.1% for these samples, respectively. Amino acid analysis indicated that tryptophan was the first limiting amino acid in all the acacia samples. Dietary fibre, calculated on defatted and ethanol extracted samples, was highest in whole A. colei with the seed coat (47.9%) and lowest in the processed A. colei (31.9%). Total soluble sugar was highest in A. tumida (14.6%). Both A. colei and A. tumida seeds contained high levels of linoleic acid. Fat soluble vitamins (carotenoids, ergocalciferol and α-tocopherol) were generally inadequate while the water-soluble vitamins (B group) were in sufficient to large quantities. Processing A. colei with water reduced thiamine, niacin, riboflavin and pantothenic acid contents by 12, 31, 42 and 74%, respectively. Potassium was the predominant mineral in all the acacia samples. Iron, magnesium, calcium and zinc were in high concentrations; the availability of iron was low but that of other elements was adequate.

Studies on some edible wild mushrooms from Nigeria: 1. Nutritional, teratogenic and toxic considerations

The biological value of 5 mushroomsChlorophyllum molybditis, Psathyrella atroumbonata, Termitomyces robustus, Termitomyces striatus andVolvariella esculenta from our collection of wild edible mushrooms were determined using weanling rats.C. molybditis supported rapid growth with PER (2.63) higher than the casein control (2.50).P. atroumbonata was average in biological performance (PER 1.50) whileT. robustus andV. esculenta did not support growth at all. Rats onT. striatus dried at 60°C for 48 h lost weight rapidly and showed pathological signs of toxicity by the second day. All rats on this died died by the fourth day of the experiment. When the diet ofT. striatus dried at 90°C for about 8 h was fed, the rats gained weight marginally but all survived. Prolonged storage ofT. striatus at 60°C for 5–8 weeks also seemed to detoxify the poisonous component such thatPER andNPR values were 0.8 and 2.0 respectively. 2 pairs each of adult rats fedC. molybditis andTricholoma lobayensis diets for 10 days were mated. Rats ofC. molybditis diet gave 5 and 6 litters each and only one of these litters seemed to have retarded growth. Rats onT. lobayensis diet did not produce any litters for 14 weeks but the female produced off-spring when mated with control male rats.

Nutritional evaluation of spent grains from sorghum malts and maize grit

Potential use of the high protein by-product of beer production from 77% sorghum malt and 23% maize grit was investigated. Red sorghum spent grains (RSSG) and white sorghum spent grains (WSSG) contained 23.4 and 19.3% crude protein (CP), 54 and 43% dietary fiber (NDF), 1.44 and 0.78% ash, 4.5 and 3.2% hexane extract and tannin content of 7.5 and 1.0 mg/g catechin equivalent respectively. Magnesium was the most abundant mineral in both RSSG and WSSG — 185 and 140 mg/kg, respectively. Calcium, zinc, iron and copper were generally low. Both samples contained cadmium 1.12 (WSSG), 1.19 (RSSG) and lead at 1.38 mg/kg. Lysine was the limiting amino acid (chemical score 0.55) in both samples. Other essential amino acids were adequate or surplus. Stearic acid was the predominant fatty acid with varying levels of lauric, myristic, palmitic, and oleic acids in both samples. Feed intake and weight gain were highest in rats fed 26.3% WSSG (contributing 50% of the diet protein) but protein efficiency ratio (PER) and net protein retention (NPR) were highest in diets where spent grains contributed just 25% of the diet protein. True digestibility of diets decreased as dietary fiber content increased such that animals on diets containing 100% spent grain protein (above 20% NDF) lost weight.

Studies on weaning diets in Nigeria: 2 protein sources

Protein isolates were extracted from melon, groundnut, and soybean cakes in an aqueous system that could potentially yield both oil and protein from oilseeds quantitatively. Protein isolates obtained were 91.2, 78.6 and 79.5% of the total protein content of melon, groundnut and soybean cakes respectively. Both cakes and isolates were assessed in a rat bioassay while breadfruit, cassava, and corn starch were also investigated as sources of carbohydrate. Results showed that there were no significant differences between feed intake, weight gain and PER of rats fed the cake and the protein isolates except in soybean. Weight gain, PER and NPR were highest in cassava-soybean protein isolate diet followed by cassavacasein diet (control) while performance was only moderate with melon- and groundnutcassava diets. With melon protein isolate, cassava and breadfruit were better carbohydrate sources than corn starch. In simulated weaning diets, cassava-sucrose-melon-soybean protein isolate based diet performed better (weight gain 33.4 g, PER 1.63, NPR 2.23) than a commercial weaning food (weight gain 30.6 g PER 1.57, NPR 2.18) while replacement of sucrose and cassava at 30% by breadfruit yielded a cost effective diet with good performance (weight gain 29.4 g, PER 1.51, NPR 2.12). Diets where soybean protein served as the sole source of protein or breadfruit, white and yellow maize ‘ogi’ served as the main source of carbohydrate performed only moderately.

Food choice and meal consumption pattern among undergraduate students in two universities in Southwestern Nigeria

The food choices and meal consumption patterns of undergraduate students from two Nigerian universities, Obafemi Awolowo University, Ile-Ife (OAU) and Adekunle Ajasin University, Akungba Akoko (AAU) (n = 402; 199 male and 203 female; overall mean age 23) were studied. The result indicated that 60% of the students (58% male and 62% female) consumed the recommended minimum number of servings of cereal, 50% of the males and 35% of the females in the carbohydrate category while 35% of the males and 42% of the females consumed enough from the meat group. More female students (40%) consumed adequate quantities of fruits and vegetables than their male counterparts (20%) while the consumption of milk and milk substitutes was low (10% male and 25% female). Most students ate twice a day substituting snacks for the third meal. More female students (48%) exceeded their energy requirement than their male counterparts (28%) while 60%, 85% and 40% did not meet the recommended dietary allowance (RDA) for protein, calcium and iron respectively. Body Mass Index (BMI) classification indicated that 29% of the students were overweight, 6% were obese while 13% of the male students were underweight. The unhealthy eating habits of Nigerian university students seemed to be a reflection of poor funding.

Chemical Composition and Starch Hydrolysis of Acacia colei and Acacia tumida Seeds

ABSTRACT Acacia seed is a promising famine food due to its ability to thrive in dry zones of the world. In this study, some chemical compounds of nutritional importance as well as starch hydrolysis in three cultivars of Acacia tumida and A. colei were determined. The crude protein was 20.6–23.0%, while extractable protein was 11.5–17.5%. Total dietary fiber (TDF) (28.5–32.7%) and soluble dietary fiber (SDF) (2.2–5.8%) were higher than values reported for most legumes. Reducing sugar range was 31.0–54.5 mg/g, while total sugar range was 137–161 mg/g. The starch content of the seed was 25.6–32.3%. The samples did not contain any alkaloid but did contain saponins. Phytate and trypsin inhibitor contents were low; oxalate was fairly high (2.2–2.6 g/100 g), but tannin was on the high side 66.0–86.7 mg/g) compared with legumes. In vitro starch digestibility was highest in A. tumida (III). Using a first-order kinetic equation, A. colei showed the highest initial rate of starch hydrolysis (t1/2 = 411.56 and 1,893....

Lysine in cassava based diets: I. A note on the effect of heat on digestibility and available lysine

Abstract Heating Conophor seeds and Amaranthus leaf protein concentrate (LPC) for 24 h at 121°C reduced the digestibility of their crude protein contents. Loss in available lysine was moderate in LPC alone and cassava-LPC mixtures heated for 24 h at 121°C (≤45% loss) but high in Conophor seeds and glucose-LPC mixtures (72 and 80% loss respectively).