The chemical composition of nigerian onions (Allium cepa, linn)

Four Nigerian cultivars of Allium cepa were analysed for the proximate chemical composition, i.e. carbohydrate constituents, mineral make-up and the amino acid pattern to provide basic information on their nutritive value. Crude protein ranged from 6·4% in ‘Kano’ to 19·6% in ‘Oyo’, ether extract from 1·7% in ‘Kano’ to 35·2% in ‘Oyo’, nitrogen-free extract (nfe) from 18·2% in ‘Oyo’ to 85·6% in ‘Kano’. Sugars identified in 80% ethanolic extracts of samples were glucose, fructose, sucrose and an oligosaccharide containing a ketose portion. Total sugars figures ranged from 13.·2% in ‘Oyo’ to 71·8% in ‘Kano’; hemicellulose, from 8·5% in ‘Zaria’ to 13·2% in ‘Oyo’; cellulose from 10·9% in ‘Kano’ to 24·6% in ‘Oyo’. Paper chromatography of hemicellulose hydrolystates of samples revealed the presence of galactose, arabinose, xylose, rhamnose and ribose. Nitrogen-free extract overestimated available carbohydrates by 19·26% to 40·04%. The onions were rich in calcium, magnesium and potassium; ‘Oyo’ was higher in iron (8·1 mg/100 g) and the essential amino acids than other cultivars.     

Amino acid composition and In Vitro digestibility of some Egyptian foods made from faba bean (Vicia faba L)

Faba beans were cooked to prepare four different dishes—Medammis, Falafel, Bissara and Nabet Soup—that are widely consumed in many Middle Eastern Countries, especially in Egypt. Amino acid composition and in vitro digestibility were determined and compared to raw beans. Severe heat-processing markedly decreased some essential amino acids, especially phenylalanine, cystine, methionine and tryptophan. Protein scores were 38·1, 21·2, 39·3, 33·7 and 42·4 for raw faba beans, Medammis, Falafel, Bissara and Nabet Soup, respectively. Cooking resulted in an appreciable increase in the in vitro digestibility which amounted to 98·4% for Nabet Soup, being close to that of casein (99·6%). The in vitro digestibility values were 75·9%, 92·7%, 85·0% and 97·2% for raw beans, Medammis, Falafel and Bissara, respectively.     

Hull-less barley for swine: ileal and faecal digestibility of proximate nutrients,amino acids and non-starch polysaccharides

The nutritive value of three hull-less barley cultivars (Condor, Falcon and CDC Buck) were evaluated. The samples were analysed for proximate composition, amino acids and non-starch polysaccharides (NSP). Wheat and normal barley were used for comparison. Apparent digestibilities were determined with eight cannulated pigs. The diets were formulated to have all energy and protein supplied by the cereals. Compared to normal barley, hull-less barley has higher contents of protein and amino-acids, and lower levels of fibre components. The levels of several essential amino acids in hull-less barley are higher than in wheat. No obvious differences in NSP composition were observed, but the hull-less barley contained considerably higher levels of β-glucan compared to hulled barley and wheat. In digestion trials the piglets did not accept the diet in which conventional barley was formulated as the only energy and protein source, whereas hull-less barleys were well consumed. The results showed that, in the order of Condor, Falcon, CDC Buck and wheat, the overall tract digestibilities of intake energy were 83·1, 80·3, 83·2 and 82·9%, and of protein were 72·6, 69·5, 76·5 and 77·6%, respectively. The averages of apparent ileal amino acid digestibility were 56·5, 58·4, 65·3 and 65·4%, respectively. Hull-less barleys showed 20–37% ileal digestibility of total NSP. This study provides digestibility coefficients of hull-less barleys, and it is concluded that the digestibility of hull-less barley is comparable to wheat and superior to hulled barley in terms of nutrient composition and acceptability. © 1998 SCI.     

Changes in nitrogen content and amino acid composition of navel oranges during ripening

Nitrogen content and composition of amino acids in juice and rind of navel oranges were studied. The compared varieties were ‘Navelina’ ‘Washington Navel’ and ‘Navelate’, early, mid-season and late types, respectively. Total N content in juice increased during the season with values from about 60 to near 100 mg 100 ml^?1 in Navelina and ‘Washington Navel’ and from 60 to about 80 mg 100 ml^?l in ‘Navelate’; amino N increased from 30 to 60 mg 100 ml^?lapproximately in the three varieties. The total N content in rind was quite similar in all cases, with values that decreased with time from 1 to around 0·6 g 100 g^?l dry weight (DW), 50–60% corresponding to the protein N. The main free amino acids in juice and rind at different maturity stages are tabulated. Proline represents at maturity around 50% of the total free amino acids in rind, with values near to 1·5 mmol 100 ml^?l in juice and over 5·0 mmol 100 g^?1 DW in rind. Total protein amino acids in rind decreased during maturation, reaching final values of about 20 mmol 100 g^?1 DW. Differences in composition among the three studied varieties are discussed.     

In-vitro protein and sulphur amino acid availability as a measure of bean protein quality

The total and ‘available’ cystine and methionine, and the in-vitro and in-vivo protein digestibilities were determined in six varieties of Phaseolus vulgaris with different seed coat colours. Reactive cystine and methionine, evaluated by chemical methods after in-vitro enzymic digestion, were taken as a measure of the availability of sulphur amino acids. Cystine ‘availability’ ranged from 43 to 51% and from 31 to 58% in raw and cooked samples, respectively, while methionine ‘availability’ was over 90%, except for the two red varieties (55% and 74%). No correlation was found between cystine and methionine ‘availability’ and in-vitro protein digestibility. In-vitro protein digestibility (76.6-80.7%) showed a good correlation (r = 0.857; P < 0.05) with in-vivo values (72.0-80.9%). Amino acid score corrected for protein digestibility and for sulphur amino acids availability, as suggested by the Codex Committee on Vegetable Proteins, seems to predict accurately the biological quality of bean protein, as was shown when in-vitro indices were compared with net protein utilisation and relative protein value.     

Changes in the hydrocyanic acid concentration during traditional processing of cassava into ‘gari’ and ‘lafun’

Two sets of 48 cassava plants, harvested at three different times, were processed using one of the traditional methods to determine the effectiveness of hydrocyanic acid reduction to innocuous levels in the cassava products ‘gari’ and ‘lafun’. Dry matter content of the cassava was 37·6%; this changed significantly with the stages of processing to 84·5% in ‘gari’. This change was due mainly to pressing and roasting. Starch content remained constant during ‘gari’ processing. Hydrocyanic acid was significantly reduced from an initial concentration of 90·1 mg/kg fresh grated pulp to 25·8 mg/kg in ‘gari’. The fermentation step was found to be most effective in the reduction. Dry matter content during ‘lafun’ processing changed from 39·3% to 86·5% due mainly to sun drying for 96 h. Hydrocyanic acid was significantly reduced from 165·5 mg/kg in fresh grated pulp to 19·6 mg/kg in ‘lafun’. Soaking in static water was responsible for three-quarters of the decrease in hydrocyanic acid.     

Kinetics of flavour and aroma changes in thermally processed cupuaçu (Theobroma grandiflorum) pulp

Changes in ‘fresh’ and ‘cooked‐notes’ during thermal treatment of cupuaçu (Theobroma grandiflorum) pulp were evaluated and modelled. Isothermal experiments in the temperature range of 70–98 °C were carried out and a non‐linear regression was performed to all data to estimate kinetic parameters. ‘Fresh’ and ‘cooked‐notes’ change followed simple first‐order (Ea = 78–82 kJ·mol⁻¹, z = 30–31 °C) and reversible first order (Ea = 80–85 kJ·mol⁻¹) kinetics, respectively. Although ‘cooked‐notes’ were linearly correlated with ‘fresh‐notes’ (R² = 0.99), the former was a better indicator for quality degradation. These results are useful to design pasteurisation processes while minimising sensory changes. © 2000 Society of Chemical Industry     

Chemical Composition,Amino Acid Content and Protein Quality of the Little-Known Legume Bauhinia purpurea L

Some nutritional and antinutritional characteristics and biological value of Bauhinia purpurea L seeds were studied. The mature seeds contained (g kg^-1 as is) 271·7 crude protein, 58·7 crude fibre, 124·5 crude fat, 29·3 ash and 515·3 carbohydrates. Potassium, phosphorus and iron occurred in higher concentrations when compared with commonly consumed legumes. The globulins and albumins together constituted major storage proteins (82% total protein). The essential amino acid profile of total seed proteins compared well with the FAO/WHO reference pattern except for a deficiency of sulphur-containing amino acids and tryptophan. When compared with the globulins, the albumins appeared to be a rich source of cystine, methionine, threonine, lysine and tryptophan. Seed lipids contained high levels of the unsaturated fatty acids, oleic and linoleic, which accounted for 62·6% of total fatty acids recovered. Both dry heating and autoclaving significantly reduced the antinutritional compounds. The in vitro protein digestibilities of raw, dry-heated and autoclaved seeds were 59·5, 72·3 and 78·7%, respectively. True digestibility and net protein utilisation were significantly higher in processed seed samples compared with raw seeds. Regarding utilisable protein, autoclaved samples exhibited relatively higher values than raw seeds. © 1997 SCI.     

A note on the nutritive value of amaranth seeds

Analysis of Amaranthus hybridus seeds shows that they contain a high amount of protein (13·1%) of high biological value. The PER (2·3) is comparable to that of casein (2·5); so also the biological value, digestibility and net protein utilïsation. The tannin content (0·15%) seems to be sufficiently low to have no significant effect on the nutritional value.     

Selection of starters for a traditional Turkish yayik butter made from yoghurt

Butter is produced from two different materials in Turkey, cream and yoghurt. The butter produced from fresh yoghurt or ‘tulum yoghurt’ (a strained yoghurt produced from cow, goat or sheep milk) is called ‘yayik butter’ and has been traditionally produced in Turkey for centuries. In this research, we attempted to isolate and identify the natural lactic acid bacteria (LAB) of yayik butter and to select the best LAB combination for butter production. Twenty samples of yayik butter were collected from Afyon, Antalya, Isparta and Konya regions in Turkey and determined to have a mean pH of 4·78±0·33, a mean titratable acidity (lactic acid) of 0·23±0·07% and a mean NaCl of 0·55±1·22%. The mean counts of LAB (log₁₀ cfu g⁻¹) were 2·66±0·84 and 1·72±0·82 on MRS agar at 30 and 42°C, 2·44±0·93 and 1·78±0·24 on M17 agar at 30 and 42°C, and 1·64±1·196 on Sodium Azide Leuconostoc agar at 21°C, respectively. Eighty-five different LAB isolates were obtained from 20 yayik butters and identified asStreptococcus salivarius ssp. thermophilus (21·2%), Streptococcus sp. (4·7%), Lactobacillus delbrueckii ssp. bulgaricus (20%), Lactobacillus casei ssp.casei (15·3%), Lactobacillus paracasei ssp. paracasei (2·3%),Enterococcus faecium (18·8%). Leuconostoc pseudomesenteroides (Leucono-stoc mesenteroides ssp. dextranicum) (7·1%), Leuconostoc gelidum (Leuconostoc mesenteroides ssp.mesenteroides ) (4·7%) and Weissella paramesenteroides (Leuconostoc paramesenteroides) (5·9%). Combinations of S. salivarius ssp. thermophilus S51, Lb. delbrueckii ssp.bulgaricus A42, Lb. casei ssp. casei K64, Lb. paracasei ssp. paracasei A27, andLeu. pseudomesenteroides E83 were used as starter bacteria for experimental butter production from cream. Six different groups of butters were produced using different combinations of these bacteria (B, C, D and E samples), commercial culture (F sample), and without culture (A sample). Sensory evaluations showed that the experimentally produced butter sample of group B was more acceptable than the other butters. In addition, the buttermilk of sample B had lowest fact content. LAB counts of experimental butters produced with combined cultures and commercial culture were similar (6·66±1·87–6·83±0·040 and 6·81±0·13 log₁₀ cfu g⁻¹ on MRS agar, respectively).     

Nutritive Utilisation of Canned Sardine Protein in Olive Oil: The Influence of the Different Elaboration Process Stages and Storage for 6 Months and 5 Years

The true digestibility coefficient (TD), the metabolic utilisation (BV) and the net protein utilisation (NPU) of canned sardines from the same production lot have been studied in the different process stages of conservation and maturing (canned): raw (RS), precooked (PS), just canned (CS) and with 6 months (6MS) and 5 years (5YS) of storage. We find that during the process there are no significant quantitative fish protein losses. Qualitatively, the PS show the lowest digestibility values (TD, 0·90±0·02) and metabolic utility (BV, 0·55±0·08). The highest digestibility is showed for the CS (TD, 0·94±0·01) and the highest BV for the 6MS (0·65±0·07). All these values are high if they are compared with their casein controls (TD, 0·95, BV, 0·71), the 6MS have the highest NPU (0·61) and although this value decreases in the 5 years of storage (NPU, 0·56), the differences are not significant.     

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

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).     

Evaluation of the effect of processing on sunflower protein quality

The protein quality of sunflower meal, sampled at different processing steps, was studied. The protein quality was evaluated in terms of the ‘available lysine’ by the modified Carpenter method, and the biological value (BV) was determined by the Tetrahymena pyriformis test. The samples obtained from two oil expressors showed little change during processing, as assessed by two analytical methods. Sunflower meal heated at 110°C for various periods showed a decrease in available lysine from 3·4% to 0·9%.     

The Nigerian diets: Distribution of protein,carbohydrate, fat,fibre and minerals

Nigerian diets consumed by population groups in the Calabar Metropolis were analysed for protein, carbohydrate, fat, fibre and mineral constituents. The crude protein content ranged between 5·4% and 26·3% (dry weight), 9·5% and 24·4% and 7·2% and 25·5% for breakfast, lunch and dinner diets, respectively. The ranges of values for carbohydrate, crude fat, crude fibre and total cholesterol were 32–83%, 9–39%, 1·3–3·9% and 54·8–1046 mg (per 100 g dry weight) respectively, for breakfasts; 43–75%, 12–30%, 1·8–3·4% and 452–900 mg, respectively, for lunch diets and 47–78%, 11–28%, 1·5–3·5% and 98·5–863 mg, respectively, for dinners. Typical Nigerian diets provided 25% of total food energy from fat. The mineral analysis provided data on twelve minerals and their distribution in the diets.The results indicate that diets consumed in the Calabar Metropolis contain moderate protein, low fat and cholesterol, high carbohydrate and dietary fibre, but the diets of elite groups approximate those of western nations in composition.     

Biochemical and nutritional evaluation of Egreria radiata (clam), a delicacy of some riverine peasant populations in Nigeria

Proximate, mineral and amino acid analyses of the edible portion of clam (Egreria radiata), a delicacy of some riverine peasant populations in Nigeria, were carried out. The protein quality of the delicacy was also evaluated in a rat bioassay. Crude protein content was 61·0 ± 0·81%; crude fat, 19·0 ± 0·33%; carbohydrate, 1·40 ± 0·02%; crude fibre, 0·40 ± 0·00%, and ash, 17·4 ± 0·51%. Among the essential amino acids assayed, valine, with a chemical score of 37·5%, appeared to be the most limiting, as others had scores of over 55%, when compared with the essential amino acid pattern of whole hen's egg. Elemental analyses showed that, of the trace elements, clam was rich in iron, zinc and manganese, and also contained reasonable amounts of other elements. The PER, NPU, TD and BV were 2·55 ± 0·35, 65·7 ± 1·80, 85·3 ± 3·90 and 77·1 ± 3·35, respectively. These values compared reasonably well with those for whole hen's egg. The high nutritional qualities of the edible portion of clam justify its consumption and also recommend its wider use as a cheap good source of animal protein.     

Effect of hydrochloric acid treatment of palm kernel for dehulling on the nutritional quality of kernel protein

The effect of hydrochloric acid treatment for the dehulling of palm kernel on the nutritional quality of its protein was studied and compared with that of untreated kernel protein and casein. Rats fed a treated defatted kernel protein diet had slightly lower gains in body weight (59·5 g) when compared to those fed a casein diet (64·2 g), while the gains in body weight in the animals fed untreated kernel protein diet were considerably lower (42·5 g). The PER of the treated protein was 2·27 (95% of that of casein) while that of the untreated protein was lower; only 1·63. In the case of the treated protein diet, 80% of food nitrogen was absorbed compared to 94% for casein and 65% for untreated protein, indicating improvement in protein digestibility with HCl treatment. The essential amino acid content of the treated kernel protein was comparable to egg protein. Available lysine content was higher in the treated sample than that of the untreated sample. © 1998 SCI.     

In-vitro digestibility of kale (Brassica oleracea) secondary xylem and parenchyma cell walls and their polysaccharide components

The cell walls of forage kale (Brassica oleracea L cvs Maris Kestrel, Vulcan and Thousandhead) stems were separated into parenchyma and secondary xylem fractions of high and low digestibility respectively. Previous work had shown that the lignified secondary xylem cell walls were the main components of the plant indigestible to ruminants. The cell walls were subjected to in-vitro digestion with fungal ‘cellulose’ and with rumen liquor. These two methods gave well correlated results except when secondary xylem cell walls were first delignified with chlorite, when their mean digestible organic matter in the dry matter (DOMD) was 41·9% with cellulase but 64·6% with rumen liquor. Chemical fractionation of the cellulase-digested residues showed that all fractions of the parenchyma cell walls, except the hemicelluloses from cv Thousandhead, were of high digestibility. In the secondary xylem cell walls the α-cellulose fraction had DOMD about 50%, the pectic fraction being more digestible and the hemicelluloses less digestible: but no one polysaccharide fraction in these cell walls was completely digested or untouched by digestion.     

Biological response to different diets of fermented and unfermented mixtures of flour and cereal brans

The objective of this study was to biologically evaluate eight mixtures of flour and brans prepared with non‐conventional foods popularly denominated ‘multimixtures’, which differed from each other in terms of type of bran (wheat or rice), presence or absence of cassava leaf powder and submission or non‐submission to a solid‐state fermentation with Saccharomyces cerevisiae for 6 h/30 °C, utilising female Wistar/UFPEL rats. Biological indices determined were food efficiency ratio (FER), protein efficiency ratio (PER), net protein efficiency ratio (NPR) and in vivo digestibility. Liver, spleen and kidney specimens were collected at the end of the experiment. In vivo digestibility of diets containing multimixtures formulated with wheat bran was superior to diets containing rice bran, presenting values from 76.5% to 82.8%, which corresponds to up to 85% of casein digestibility. The results allowed the conclusion that fermentation tended to improve food efficiency, but did not influence in vivo digestibility.     

Determination of True Ileal Amino Acid Digestibility in Feedstuffs for Pigs with the Linear Relationships between Distal Ileal Outputs and Dietary Inputs of Amino Acids

This study was carried out to investigate the methodological aspects of extrapolating the ileal losses of endogenous amino acids (AA) with linear relationships between the distal ileal outputs and dietary inputs of AA. Six barrows, average initial body weight 35 kg, were fitted with a simple T-cannula at the distal ileum and fed six diets according to a 6×6 Latin square design. Six maize starch-based diets containing six levels of crude protein (CP) and AA from soya bean meal (4, 8, 12, 16, 20 and 24% CP, respectively) were formulated. Chromic oxide (4 g kg^-1 diet) was included as the digestibility marker. Each experimental period consisted of 8 days. Ileal digesta were collected, at 2 h intervals, for a total of 24 h during days 7 and 8. There were strong linear relationships (P<0·01) between the ileal outputs and dietary inputs of AA. Differences in ranges of graded dietary levels of AA affected the linearity and caused large differences in the extrapolated levels of ileal endogenous AA. Therefore, the design of a suitable range of graded dietary levels of AA is the most important methodological consideration for the determination of endogenous AA losses and the true ileal digestibility values of AA with the linear relationship. For CP and the essential AA, the true ileal digestibility values (%) in soya bean meal and the ileal endogenous losses (g kg^-1 dry matter intake, in parentheses) were as follows: CP, 89·4 (16·4); arginine, 96·1 (0·68); histidine, 92·4 (0·24); isoleucine, 91·7 (0·45); leucine, 90·7 (0·69); lysine, 90·5 (0·48); methionine, 93·6 (0·13); phenyl-alanine, 92·5 (0·38); threonine, 86·5 (0·71) and valine, 90·3 (0·56). Furthermore, the levels of endogenous AA extrapolated with the linear relationships between the ileal outputs and dietary inputs of AA were very close to the values estimated with the linear relationships between the dietary contents of apparent ileal digestible and total AA, suggesting that both models of linear relationships can be used as the regression analysis technique for determination of ileal losses of endogenous AA and true ileal digestibility values of AA in feedstuffs for pigs. © 1997 SCI.     

A comparative study of oat (Avena sativa) cultivars as brewing adjuncts

Brewing with high levels of unmalted oats (Avena sativa) has proven to be successful despite their high contents of β-glucan, protein, and fat. However, little is known about the effect of different oat cultivars on the quality and processability of mashes and worts. Therefore, the aim of this study was to compare the mashing performance of eight oat cultivars, selected because of their low contents of β-glucan, protein, fat, and/or high starch content, when substituting 20 or 40 % barley malt. For this purpose, seven husked (A. sativa L. ‘Lutz’, ‘Buggy’, ‘Galaxy’, ‘Scorpion’, ‘Typhon’, ‘Ivory’, ‘Curly’) and one naked oat cultivar (A. sativa var. nuda ‘NORD 07/711’) were fully characterized using standard methods, Lab-on-a-Chip capillary electrophoresis, and scanning electron microscopy. The rheological behavior of mashes containing up to 40 % of each oat cultivar was measured during mashing by applying a Physica MCR rheometer. In addition, the quality of worts obtained from laboratory-scale mashing trials was analyzed particularly with regard to their cytolytic, proteolytic, and amylolytic properties. The substitution of up to 40 % barley malt with husked or naked oats resulted in significantly higher pH values, β-glucan contents, and viscosities as well as significantly lower soluble nitrogen and polyphenol contents, color values, filtration rates, and apparent attenuation limits. Naked oats contained significantly less β-glucan as well as more protein and starch than the seven husked oat cultivars. The replacement of barley malt with naked oats resulted in a constant extract yield, whereas the use of husked oats caused significant extract losses.