O.L. Oke

Chemical composition of papaya (Carica papaya) seeds

Abstract Defatted and undefatted seeds of papaya (Carica papaya) were analyzed for proximate composition, some toxicants, sugar composition, mineral content, physico-chemical properties of the seed oil and the fatty acid spectrum of the seed oil. The seed is a rich source of proteins (27·8% undefatted, 44·4% defatted), lipids (28·3% undefatted) and crude fibre (22·6% undefatted, 31·8% defatted). Of the toxicants estimated, glucosinolates occur in the highest proportion. The seed is low in free monosaccharides. Sucrose is the predominant sugar (75·0% of total sugars). Mineral content is generally low. However, Ca and P occur in appreciable quantities (17 340 μg/g and 10 250 μ/g, respectively). The seed oil is low in iodine value (74·8), free fatty acids (0·94%) and carotene (0·02 μg/g). The major fatty acid is C18:1 (79·1%).

Factors affecting the processing of wara—A Nigerian white cheese

Abstract Wara was prepared in the laboratory in the traditional way and factors affecting the processing were investigated. The juice from sodom apple (Calotropis procera), used for coagulating the curd, showed minimal activities at temperatures below 37°C at pH 6·30. Cold storage for 2 weeks did not seem to affect the enzyme activity. At 40°C the milk clotting time (mct) dropped sharply to 26 min and this levelled out gradually to 1 min at 70–80°C. The mct varied inversely with the amount of the enzyme extract, ranging from 67 min with 0·5 ml to 22 min with 2·5 ml, while yield of wara increased from 28·5% with 0·5 ml to a maximum of 33·7% at 1·5 ml and then dropped to 30·5% with 2·5 ml. Beyond 2 ml of the extract the product had a bitter taste and poor texture whereas, within the range 0·5 to 1·5 ml, it was satisfactory. The most dramatic change in the composition when milk was made into wara was the disappearance of the lactose which was reduced from 4·6% to 0·2%. The protein was increased fourfold (3·7–14·8%) and the fat threefold (4·3–13·5%).

Three edible wild mushrooms from Nigeria : Their proximate and mineral composition

The pilei (caps) and the stipes (stalks) of the button and early open-cap (cup) stages ofLentinus subnudus, Psathyrella atroumbonata andTermitomyces striatus were assayed separately for their proximate and mineral composition. The differences observed in the contents of some of the proximate components seem to be related to species and mushroom parts.P. atroumbonata was richest in crude and true protein,L. subnudus was richer in crude fiber, ash and carbohydrates. Mineral contents appeared to be dependent on type and parts of the mushrooms analysed. The three mushrooms were good sources of magnesium, zinc and iron.L. subnudus contained between 14.83 and 20.00 ppm of iron,P. atroumbonata contained between 20.01 and 22.09 ppm andT. striatus contained between 17.13 and 22.93 ppm of iron. The pilei ofP. atroumbonata andT. striatus are very good sources of zinc. Zinc contents for the pilei ofP. atroumbonata were 63.81 and 64.94 ppm respectively. Zinc contents forT. striatus were 90.45 and 92.49 ppm respectively.

Determination of fatty acid composition of amaranthus species

Fatty acid compositions of the seed oils from eighteen vareties of amaranthus species have been determined after room temperature transesterification. Consistent with earlier studies, wide variations in the fatty acid composition are reported, and appear to be agronomically related. All variaties show significant levels (2–5%) of squalene and a combined linoleic acid and olaic acid occurrence of between 70–-80%. This study represents the frist reported fatty acid composition of grain amaranthus cultivated in West Africa.

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.

Some studies on the proteins of Carica papaya seeds

Abstract Protein isolates and seed meals made from Carica papaya seeds were studied with respect to their composition and functional properties. Studies showed that the seed proteins are most soluble in 5% NaCl (23·77 ± 0·15%). In all concentrations of NaCl tested, the protein has a solubility peak at pH 8·0. Classification of the protein showed that globulins constitute the bulk of the protein (53·9 ± 0·89%). The amino acid pattern of the samples studied is not too different from other plant protein sources. However, the seed appeared deficient in many amino acids. Electrophoretic studies showed that the water extract had only one band with a molecular mass of about 70·7 × 10 3 daltons. The 5% NaCl extract gave five bands, with molecular mass ranging from 37·6 to 105·9 × 10 3 daltons while the NaOH-soluble fraction gave six bands with a range of 18·2 to 104·0 × 10 3 daltons. Compared to soya bean meal and protein concentrate, the papaya products were inferior in terms of functional properties.

Bioavailability to rats of iron from fortified grain amaranth

In this study, fortified and unfortified grain amaranth seed flour diets and a FeSO4-fortified casein diet (used as a control) were evaluated for their iron (Fe) bioavailability. NaFeEDTA, ferrous fumarate, and FeSO4-fortified grain amaranth were fed to growing Sprague-Dawley weaning male rats. Iron intake, hemoglobin iron (HbFe) gain, Fe availability, total iron binding capacity (TIBC), serum iron, non-haem liver iron and red bloodcell volume (RBV) were determined, and the values were compared with those of the FeSO4-fortified casein diet control. Ferrous fumarate fortified diets gave consistently high values for all these parameters, compared with consistently low values for the amaranth diet without iron fortification.Relative biological values (RBVs) were 0.40, 1.55, 1.75, 1.67 and 1.00 for animals fed on an unfortified amaranth diet, and diets fortified with NaFeEDTA, ferrous fumarate, FeSO4 and casein fortified with FeSO4, respectively. Using FeSO4-fortified casein as control, ferrous fumarate gave a superior RBVs (1.75 vs. 1.00). The RBVs, of the unfortified cereal diets were 40% that of the control, perhaps suggesting low iron absorption from the amaranth cereal. Based on the results of this study, amaranth cereal can be considered an ideal food vehicle for iron fortification. The iron fortification of choice is ferrous fumarate.

Some chemical changes in heated crude palm oil

Abstract Palm oil was heated for 2h at a time at 100°, 150° or 200°C and then allowed to cool for 10 or 58h. This was repeated twelve times. For the chemical monitoring of deterioration, the following parameters were measured: iodine value, free fatty acids, peroxide, anisidine, oxidation and thiobarbituric acid values, as well as the carotenes and fatty acid composition. Destruction of carotenes and linoleic acid (C18:2) contributed significantly to increases in peroxide value, p-anisidine value and thiobarbituric acid value at 452nm. Oleic acid (C18:1) did not contribute significantly to these oxidation parameters. Hydrolysis and polymerisation, as indicated, respectively, by the free fatty acids and iodine value, did not play any significant role in the deterioration of the heated samples of palm oil.

Effects of different levels of palm oil and sulphur in cassava-based diets

Abstract The effects of different levels of palm oil and sulphur on the nutritive value of a cassava leaf protein diet was investigated using rats. With 40% cassava and no palm oil, the protein efficiency ratio (PER) and net protein utilisation (NPU) were very low (0·3 and 23·8, respectively) but the true digestibility was the same as that of the casein control (95·0%). With 5% palm oil there was no improvement in PER but both the NPU and biological value (BV) were increased appreciably (38·1 and 40·3, respectively). The best result was obtained with 10% palm oil, with which the PER was more than doubled (0·7) and there were similar increases in both the NPU and BV (46·6 and 48·9, respectively). Cassava at the 40% level was supplemented with various sources of sulphur—i.e. methionine, sodium thiosulphate, elemental sulphur, sodium sulphate and ferrous sulphate. With methionine, the PER, compared with the control (0·7), was more than trebled (2·2) and the NPU and BV were also significantly increased (72·6 and 83·3, respectively). Elemental sulphur gave a PER of 1·8 whilst sodium sulphate and ferrous sulphate gave 1·9. The lowest PER was obtained from sodium thiosulphate (1·1). The importance of palm oil and sulphur donors in cassava-based diets is discussed.

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).