Legume seed vicilins (7S storage proteins) interfere with the development of the cowpea weevil (Callosobruchus maculatus (F))

Vicilins (7S storage proteins) isolated from the seeds of the legumes Vigna unguiculata (cowpea), Vigna angularis (adzuki bean), Canavalia ensiformis (jack bean), Glycine max (soybean), Phaseolus vulgaris (common bean) and Phaseolus lunatus (lima bean) were shown to be immunologically related and to bind to a chitin matrix. The effect of the isolated vicilins on the development of the cowpea weevil Callosobruchus maculatus was examined. Vicilins from all non-host seeds, including those of the C maculatus-resistant cowpea line IT81D-1045, strongly inhibited larval development (ED₅₀ of 1·07±0·32% to 2·22±0·64%). Vicilins from the C maculatus-susceptible cowpea CE-31 and adzuki bean seeds were the exception with ED₅₀ of 6·25±0·75% and 5·40±1·54%, respectively. These results correlate well with the host range of C maculatus and are possibly a reflection of the low digestibility of vicilins by insect midgut proteinases in addition to the ability they show in binding to chitin-containing structures like the ones found in the bruchid midguts. © 1998 SCI.     

Effects of ingredients on the characteristics of rice cakes

Steamed leavened rice cakes made from rice flour, sugar, water, yeast or baking powder were used to study the effects of ingredients on cereal-based cakes. Volume expansion linearly correlates to amylopectin and negatively correlates to amylose content (r²=0·84), with an optimum amylose/amylopectin ratio of approximately 1: 8. Higher amylopectin content resulted in sticky, elastic and unacceptable cake. The optimum water content for volume expansion was in the range of 90±5% by weight of rice flour. Sugar content correlates linearly with volume expansion and tenderness of chemically leavened rice cakes (CLRC) (r²=0·99 and 0·92, respectively). Sugar content above 50% of rice flour weight decreased volume and softness of yeast-leavened rice cakes (YLRC). Tenderness of YLRC correlates linearly to fat content (r²=0·98), but volume expansions correlates negatively to the square root of fat content (r²=0·81 and 0·97 for the two rice cakes). Both tenderness (r²>0·92) and volume expansion (r²>0·93) correlates linearly with emulsifier content up to 3% by weight of rice flour, above which the cake becomes crumbly. A little salt increased hardness, but further increase reduced both volume expansion and hardness of rice cakes. Skimmed milk powder greatly increased the expansion of CLRC. Ovalbumin content correlates linearly to volume expansion of YLRC (r²=0·87) but negatively to the expansion of CLRC (r²=0·96). The proteins that improved the textures of rice cakes were skimmed milk and egg white with an optimum content of 2–4%. Egg yolk, soya protein, whey powder and wheat gluten reduced both tenderness and volume expansion. The effects of the various ingredients interacting together were studied and the optimum formulations was determined using a Random Centroid Optimisation Program. © 1998 SCI.     

Epoxy and cyclopropenoid fatty acids in Syzygium cuminii seed oil

Syzygium cuminii syn Eugenia jambolana seed oil was found to contain lauric (2·8%), myristic (31·7%), palmitic (4·7%), stearic (6·5%), oleic (32·2%), linoleic (16·1%), malvalic (1·2%), sterculic (1·8%) and vernolic (3·0%) acids.     

Wet Milling Comparison of Quality Protein Maize and Normal Maize

Quality protein maize (QPM) experimental hybrids and normal maize possessing different physical and chemical properties were studied as the raw material for wet milling. Maize samples were steeped for 36 h in a 600-ml solution containing 15 g kg⁻¹ lactic acid and 0·5 g kg⁻¹ SO₂ followed by 12 h in a second 600-ml solution containing 5 g kg⁻¹ lactic acid and 1 g kg⁻¹ SO₂. The steeped grain was then wet milled and the yields and purity of fractions were analysed. Water-soluble solids, kernel size, quality protein, total dietary fibre and ash content were higher in QPM samples than in normal maize. Water-soluble solids were positively correlated to kernel size ( r =0·97, P< 0·05), test weight ( r =0·83, P< 0·05) and density ( r =0·57, P< 0·05). Total fraction recovery for the five hybrids tested ranged from 921 to 955 g kg⁻¹, with the highest values corresponding to QPM hybrids. QPM hybrids yielded slightly higher starch content than normal maize. Gluten yields of QPM-HO (high oil) presented the highest values. The lysine contents of kernel, gluten and milling solubles were highest for QPM hybrids. QPM contained more palmitic acid than the other hybrids. The H-137 normal maize and QPM yellow dent-HO contained more oleic and linolenic acids than the other samples, and the QPM white-C (corneous) contained more linoleic acid than QPM-HO and normal maize.     

Determination of Triacylglycerol Classes and Molecular Species in Seed Oils with High Content of Linoleic and Linolenic Fatty Acids

Soya bean and linseed oils were analysed by successive application of silver-ion and reversed-phase thin-layer chromatography and densitometry. Direct quantitative determination of all the 20 possible triacylglycerol (TAG) classes including critical pairs (SD₂+S₂T; M₂T+D₃; SDT+MDT; ST₂+MT₂) was performed. TAG molecular species down to 0·1% (32 in soya bean oil and 26 in linseed oil) were identified and quantified. The detection limit was 0·2 μg and the standard deviation between 0·1% and 1·0% for silver ion thin-layer chromatography (TLC) and between 0.1% and 3.9% for reversed-phase TLC determinations. The accuracy of the analysis was confirmed by the good agreement between the quantitative results for the fatty acid composition as determined by gas chromatography and as calculated from the densitometric data for the TAG composition.     

Effect of calcium and calmodulin antagonists on ethylene biosynthesis in tomato fruits

The aim of this work was to elucidate the mode of action of calcium in calcium-inhibited ethylene biosynthesis. In one experiment, mature green tomatoes were treated with 1·5% (w/v) CaCl₂+60 μM N-6(aminohexyl)-1-naphthalenesulphonamide (W5). 1·5% (w/v) CaCl₂+60 μM N-6(aminohexyl)-5-chloro-1-naphthalenesulphonamide (W7), 1·5% (w/v) CaCl₂ alone or distilled water (control). The control and the W7 treatment had much higher ethylene production than either the CaCl₂ treatment alone or the CaCl₂+W5 treatment. In another experiment, similar tomatoes were treated with 1·5% (w/v) CaCl₂+15 μM trifluoperazine (TFP). 1·5% (w/v) CaCl₂ only, or distilled water (control). The treatment with 1·5% CaCl₂+15 μM TFP gave higher ethylene production than 1·5% (w/v) CaCl₂ without TFP, and nearly the same level as the control towards the end of the experimental period. For enzyme and intermediate metabolite assays, mature green tomatoes were treated with 1·5% (w/v) CaCl₂ plus either W5 or W7. W5 treatment had a lower ethylene forming enzyme (EFE) activity, higher 1-aminocyclopropane-1-carboxylic acid (ACC) concentration, similar levels of ACC synthase activity and 1-(malonylamino)-cyclopropane-1-carboxylic acid concentration, compared to the control and W7 treatment. As W7 is a more potent calmodulin antagonist than W5, these results suggest a calcium-calmodulin inactivation of EFE activity. © 1998 SCI.     

Chemical evaluation of the nutritive value of seeds of African breadfruit (Treculia africana)

The chemical composition and nutritive value of the seeds of African breadfruit, Treculia africana, Decne var. Africana, have been investigated.Analysis of the seeds showed that they contained, in terms of dry weight, 13·4% protein, 18·9% lipid, 58·1% carbohydrate, 1·4% crude fibre and 2·1% ash. The moisture content was found to be 7·8% in terms of wet weight.The mineral elements determined were Na, 7·0mg%; Mg, 184mg%; Ca, 17·5mg%; K, 585mg%; P, 382mg%; Cu, 3·9mg%; Fe, 1·6mg%; Cr, 0·20mg% and Zn, 7·5mg%.Vitamins B₁, 0·5mg%; B₂, 0·3mg% C, 45·1mg% and β-carotene, 6·0mg% were found to be present in the seeds. The levels of some toxic substances in the seeds were oxalate (soluble), 2·5mg% (total), 3·0mg%; phytate, 2·0mg%; tannin, 15·0mg% and HCN, 1·1mg%. The amino acid composition of the seeds has been studied and the results show that some amino acids are present at high concentrations whilst others are present at only low, or undetectable, levels.     

Cassava and soyabean flours and resting time effects on sensory and physical characteristics of reconstituted miondo

Sensory and physical characteristics of miondo made with three types of cassava flour (CF) (CF1, shredding of roots and drying; CF2, shredding of roots, 24-h natural fermentation, and drying; CF3, 3-day steeping of roots and drying) containing 0, 5 and 10% of added soybean flour (SF) were evaluated after 0, 1, 2, 3 and 4 h of resting (RT) before cooking to determine the optimum CF and SF levels and RT. Results indicated that miondo made with CF3 were more palatable (P<0·05) and firmer (P<0·05) than those of CF1 and CF2. Upon resting, there was no significant changes in sensory characteristics of cooked miondo, although the instrumental firmness (hardness) of miondo (made with CF3) increased (P<0·05). Upon addition of SF, products became less palatable, more yellow in colour, softer, less sticky; weight loss of raw miondo decreased; water retention ratio (WRR), crude protein contents, and total ashes of CF3 increased. WRR and protein content of CF3–SF blends correlated negatively with hardness of miondo (r=-0·90 and -0·99, respectively). CF3 with no added SF was most appropriate for making palatable miondo, regardless of the resting time. © 1998 SCI.     

Chemical evaluation of the effect of roasting on the nutritive value of maize (Zea mays, Linn.)

This study reports on the effects of roasting on the chemical composition of maize (Zea mays). Proximate analysis showed no significant difference (p > 0·05) between raw and roasted maize in ether extract, crude protein, crude fibre, ash and carbohydrate content; except moisture content (p < 0·05), which showed a 42·3% decrease. Elemental composition analysis showed decreases of potassium (13·8%) and calcium (41·1%). Significant differences (p < 0·05) were observed for vitamins B₁, B₂ and C contents with 26·8%, 32·4% and 35·1% destruction, respectively. Amino acid analysis showed losses for lysine (26·7%), iso-leucine (20·8%) and leucine (23·4%).There was significant (p < 0·05) variation in phytic acid, oxalic acid, tannin and hydrocyanic acid with reductions of 15·4%, 6·02%, 51·3% and 34·6% respectively.The effect of these changes on the nutritive value of roasted maize is discussed.     

In-vitro multienzyme digestibility of protein of some plant source flours blended with bovine plasma protein concentrate

The in-vitro multienzyme protein digestibilities of the flours of maize, cassava, pigeon pea (Cajanus cajan), African yambean (Sphenostylis stenocarpa) and bambara groundnut (Vigna subterranea), blended with bovine plasma protein concentrate were investigated. The multienzyme system consists of trypsin, chymotrypsin and peptidase. It was found that the addition of bovine plasma protein concentrate improved the protein digestibility of the flours compared with flours without the additive. The digestibilities were increased by between 3% in bambara groundnut blended flour to about 10% in cassava blended flour. When the flours were wet-heat treated, the digestibilities further increased in all samples with increments between 7·5 % in bambara groundnut and 16·6% in cassava flour. Bovine plasma protein concentrate may be a good source of protein for the fortification of protein-deficient foods, particularly maize and cassava flours.     

Proximate Composition and Seed Lipid Components of Sorghum Cultivars from Argentina

Seeds of 11 sorghum cultivars ( Sorghum bicolor ) from Argentina were analysed for proximate composition, fatty acids and sterols. Oil, protein, carbohydrate and ash contents varied between 41 and 66 g kg⁻¹, 111 and 156 g kg⁻¹, 670 and 730 g kg⁻¹ and 13·8 and 20·6 g kg⁻¹ of dry matter, respectively. Fatty acid profiles revealed that the major acids were palmitic (15·1–24·8%), oleic (29·9–41·8%) and linoleic (35·9–51·3%). Unsaponifiable matter was examined for sterols. Sitosterol was the prominent component in all cultivars (43·8–57·9%), followed by campesterol (18·7–29·1%) and stigmasterol (12·4–20·5%).     

Instrumental Assessments of Japanese White Salted Noodle Quality

Strong correlations were found between some sensory evaluation results and instrumentally (Instron, Model 4301) assessed quality parameters for Japanese white salted noodles made from 32 Australian wheats. The sensory texture parameter, softness, had a strong negative correlation (r=-0·74, P<0·001) with the instrumental texture parameter, cutting force peak area divided by time. Other sensory texture parameters, smoothness and elasticity, showed significant correlations with another instrumental parameter, compression force peak area divided by time (r=-0·58, P<0·001 and r=0·52, P<0·01 respectively). Brightness, yellowness and discolouration of both raw and cooked noodles were measured using a colorimeter (Minolta, Model CR310). Strong correlations were observed between yellowness and discolouration of raw noodles and CIELAB b* (r=-0·79, P<0·001) and L*a* (r=-0·63, P<0·001) values, respectively. Similar relationships were found for cooked noodles (r=-0·74, P<0·001 for yellowness and r=-0·53, P<0·01 for discolouration). Both flour pasting properties including the flour swelling test and mixograph dough properties showed strong correlations with instrumental measures of noodle texture. Protein and ash content significantly affected noodle colour. In an attempt to simplify objective noodle quality measurements instrumental texture tests were carried out on flour gels. Textural measurements of flour gels showed that sensory softness of cooked noodles was correlated with an instrumental parameter, cutting peak force divided by time (r=-0·46, P<0·01). However, in this study no strong correlations were found between the smoothness and elasticity of noodles and any parameters of compression force-time profiles derived from gels. Yellowness of flour gels measured by a colorimeter showed a significant correlation with that of cooked noodles (r=-0·68, P<0·001). © 1997 SCI.     

The chemical composition,the nutritive value and the functional properties of malt sprout and its components (acrospires,rootlets and husks)

The components of malt sprouts were effectively separated by manual winnowing into acrospires (15·3%), rootlets (40·1%) and husks (43·7%). The bitter taste was located in the acrospires. Percent recovery of protein and fibre was, respectively, 95·2 and 87·2 of malt sprouts. The acrospires were rich in protein (30·3%) and sugars (45·7%) but low in calcium (1·94 g kg⁻¹), fibre content (4·6%) and essential amino acids. They had moderate functional properties. The rootlets were rich in calcium (19·9 g kg⁻¹) and in protein (31·9%), which had a good nutritive value (low in phytic acid and polyphenols content). They had a moderate fibre content (10·7%). Consequently, they had the highest water absorption, oil absorption and emulsification capacities. The rootlets had relatively low foam capacity but the highest foam stability. The husks were rich in fibre content (25%) but moderate in protein content (12·4%), which was rich in essential amino acids. The husks were relatively low in calcium (11·83 g kg⁻¹) and phosphorus (6·53 g kg⁻¹) contents and in vitro protein digestibility (68·9%). Their functional properties were influenced by high fibre and moderate protein contents. The first limiting amino acids were sulphur-containing ones in the malt sprouts, the acrospires and the rootlets, but it was leucine in the husks. © 1997 SCI.     

Protein Contents,Amino Acid Compositions and Nitrogen-to-Protein Conversion Factors for Cassava Roots

Root protein contents of 15 cassava varieties ( Manihot esculenta Crantz) ranged from 5 to 19 g kg⁻¹ dry matter. Intervarietal differences in amino acid profiles of cassava roots were evident. Differences in the levels of aspartic acid, glutamic acid and arginine were most notable. The nitrogen-to-protein conversion factors ( k _AA ) based on nitrogen recovered from total amino acid analyses including ammonia ranged from 4·75 to 5·87, showing that the traditional conversion factor of 6·25 was not valid for cassava root proteins. Conversion factors ( k _P ) for 15 cassava varieties based on Kjeldahl nitrogen ranged from 2·49 to 3·67. Therefore an average k _P value of 3·24±0·31 may provide a better estimate of the protein content in cassava roots.     

Nutrient contents,rumen protein degradability and antinutritional factors in some colour- and white-flowering cultivars of Vicia faba beans

Six colour-flowering (Scirocco, Alfred, Carola, Condor, Tina and Herz Freya) and six white-flowering (Caspar, Albatros, Gloria, Tyrol, Vasco and Cresta) cultivars of Vicia faba were studied. The crude protein contents of colour- and white-flowering cultivars were 267±13·6 and 283±18·8 g kg⁻¹, respectively, which did not differ significantly at P<0·05. The levels of lipids, crude fibre, starch and ash varied from 14 to 22 g kg⁻¹, 88 to 143 g kg⁻¹, 407 to 485 g kg⁻¹ and 32 to 42 g kg⁻¹, respectively. The calculated organic matter digestibility (OMD) and metabolisable energy (ME) of the white-flowering cultivars were significantly higher (P<0·001) than those of the colour-flowering cultivars (OMD: 889·1±26·6 g kg⁻¹ vs 797·5±17·1 g kg⁻¹; ME: 13·97±0·49 vs 12·30±0·34 MJ kg⁻¹). In all cultivars, sulphur amino acids were lower than adequate concentration when compared with recommended amino acid pattern of FAO/WHO/UNO reference protein for a 2–5-year-old child. The in vitro rumen nitrogen degradability of colour-flowering cultivars was significantly lower (P<0·01) compared to that of white-flowering cultivars (71·4±9·3% vs 88·0±11·1%). Amongst colour-flowering varieties, the contents of total phenols (TP), tannins (T) and condensed tannins (CT) were highest in Alfred (28·3, 21·0 and 35·4 g kg⁻¹, respectively). The contents of TP and T were similar (about 15 and 10 g kg⁻¹, respectively) in Carola, Tina and Herz Freya, and the CT were in the order: Condor>Herz Freya>Carola. The CT were not detected in white-flowering varieties, T were virtually absent and TP were extremely low (4·0–4·9 g kg⁻¹). The activities of other antinutritional factors (white- and colour-flowering cultivars, respectively: trypsin inhibitor activity 3·05±0·34 and 1·85±0·09 mg trypsin inhibited g⁻¹; lectin 27·2±9·4 and 27·1±5·1 mg ml⁻¹ assay medium producing haemagglutination; phytate 15·0±2·7 and 16·6±2·3 g kg⁻¹) were very low. A strong negative correlation (r=-0·92, P<0·001) between tannins and in vitro rumen protein degradability was observed which suggested that tannins have adverse effect on protein degradability. Similarly negative correlations between tannin levels and metabolisable energy (r=-0·89; P<0·001) and organic matter digestibility (r=-0·89; P<0·001) were observed. The correlation coefficient between trypsin inhibitor activity and tannins was negative and highly significant (r=-0·88, P<0·001), whereas between tannins and saponins it was significantly positive (r=0·96, P<0·001). ©1997 SCI     

Response of nutrient digestibilities to feeding diets with low and high levels of soybean trypsin inhibitors in growing pigs

Studies were carried out to determine the effect of dietary soybean trypsin inhibitor (SBTI) content on nutrient and energy digestibilities in growing pigs. Six barrows, average initial body weight (BW) 47·8±4·0 kg, were fitted with a simple T-cannula at the distal ileum and fed two diets according to a crossover design. Two maize starch-based diets were formulated to contain 200 g crude protein (CP) kg⁻¹ from either Nutrisoy (a food-grade defatted soy flour) or autoclaved Nutrisoy. The contents of SBTI in the Nutrisoy and autoclaved Nutrisoy diets were 13·4 and 3·0 g kg⁻¹, respectively. The experiment consisted of two periods of 12 days each. The average BW at the start of the first and second experimental periods were 53·3±3·7 and 61·0±5·1 kg, respectively. The average BW at the conclusion of the experiment was 71·8±7·6 kg. The ileal digestibilities of dry matter (DM), organic (OM), energy, CP and all amino acids measured were higher (P<0·01) in pigs fed the autoclaved Nutrisoy diet. The energy digestibility increased from 66·0 to 77·9%, and the CP digestibility increased from 37·4 to 77·1%. The increases in ileal digestibilities of the indispensable amino acids ranged from 27·0 (methionine) to 49·2 (leucine) percentage units. The increases in ileal digestibilities of the dispensable amino acids ranged from 30·2 (aspartic acid) to 50·8 (tyrosine) percentage units. The faecal digestibilities of all criteria measured were also higher (P<0·01) in pigs fed the autoclaved Nutrisoy diet. Furthermore, there was a greater (P<0·01) net disappearance (g kg⁻¹ DM intake) of DM, OM, CP, energy and all amino acids in the large intestine of pigs fed the Nutrisoy diet. In conclusion, feeding diets containing high levels of SBTI decreased both ileal and faecal digestibilities of all criteria measured. The formation of SBTI-enzyme complexes is likely to be responsible for the reduction in protein digestion and amino acid absorption. © 1998 SCI.     

Nutritional and anti-nutritional characteristics of mucuna (Mucuna utilis) bean seeds

Some nutritional and anti-nutritional characteristics of mucuna (Mucuna utilis (Wight) Burck) bean seeds were studied. The mature seeds contained 264 g crude protein, 63 g crude fibre, 41 g crude fat, 37 g ash and 595 g carbohydrates kg^?1 DM. The essential amino acid profile compared well with the FAO/WHO scoring pattern except for a deficiency of sulphur-containing amino acids. Mineral composition was similar to those reported for most tropical grain legumes. Raw mucuna seed samples contained moderately high levels of anti-tryptic activity (2170 trypsin units inhibited g^?1 DM), but this was completely destroyed by cooking. The other anti-nutritional factors (phytate, cyanide and tannins) are probably of little nutritional significance provided that the beans are properly processed. The in-vitro protein digestibility of raw and cooked beans were 71·5 and 80·3 %, respectively. In view of the high L-DOPA contents reported in some mucuna cultivars, overconsumption of mucuna beans should be viewed with some caution until suitable processing methods are developed.     

Genetic and Environmental Variation for Seed Yield,Protein, Lipid and Amino Acid Composition in Cowpea (Vigna unguiculata (L) Walp)

The genetic and environmental variability for seed yield (kg ha^-1), protein content (g kg^-1 DM), lipid content (mg g^-1 DM) and essential amino acid composition (g per 16 gN) of cowpea seeds using 15 cultivars grown in three locations (Kano (12°00′ N 8°31′ E), Mokwa (9°17′ N 5°04′ E) and Ago-Iwoye (6°58′ N 4°00′ E)) that differ markedly in climate was studied. The environmental effect accounted largely for the variability observed in yield (93%), protein (71%), lipid (100%), threonine (96%), cystine (80%) and arginine (81%) while the genotypic effect accounted largely for the variability observed in methionine (56%) and lysine (51%) contents. Correlation coefficients (pooled data) from the three locations indicated that yield was negatively correlated to protein content (r=-0·87, P<0·001) and positively correlated to lipid content (r=0·73, P<0·001). Protein content was negatively correlated to lipid content (r=-0·67, P<0·001) and positively correlated to threonine (r=0·66, P<0·01), cystine (r=0·69, P<0·001) and methionine (r=0·88, P<0·001) contents. Similarly, yield was positively correlated to threonine (r=0·22, 0·01<P<0·05), cystine (r=0·38, 0·001<P<0·01) and methionine (r=0·67, 0·001<P<0·01). Yield showed a strong negative correlation with protein content (r=-0·81) and a strong positive correlation with lipid content (r=0·97) at the environmental level. Cystine, methionine and to some extent, threonine were the limiting amino acids in the three environments. This research established the degree of variability for these characters in cowpea and indicated that concurrent selection for yield, lipid content, threonine and sulphur amino acids compositions is feasible. © 1997 SCI.     

Chemical and physico-chemical characterisation of fibres from Laminaria digitata (kombu breton): A physiological approach

The content and chemical composition of soluble and insoluble dietary fibres from the brown marine alga Laminaria digitata (kombu breton) were determined. Two enzymic-gravimetric methods were used to determine (1) the content of soluble and insoluble fibres according to a modification of the AOAC procedure, and (2) the distribution of the soluble fibres in saline buffer at 37°C and at pH 2·0 and 7·5 used to simulate the gastric and intestinal phases of digestion, respectively. The total dietary fibre contents obtained by the two methods were similar (37·3 and 40·0%) and of these 84·8–87·4% was soluble. A partitioning of soluble fibres may occur during digestion since 49·3% was recovered in saline buffer at pH 2·0 whereas 50·7% was recovered in saline buffer at pH 7·5. Solubility of dietary fibres was related to the chemistry of brown algal polysaccharides. Fucans and laminarans were essentially soluble at pH 2·0 and alginate at pH 7·5, and insoluble fibres consisted primarily of cellulose. Oil adsorption and hydration properties (uptake, retention and swelling) in water, 154 mM NaCl, and 38 mM CaCl₂ at 20 and 37°C of three particle sizes of L digitata were measured. Oil adsorption was low (0·16–0·41 g g^?1) and was related to the particle size of the fibres. Hydration properties were more important with small particles except in CaCl₂ solution and followed the order water > NaCl > CaCl₂. Water uptake and swelling were greater at 37°C than at 20°C. The overall decrease in hydration properties observed with solutions of ionic strength ～0·15 was interpreted as reflecting the decrease in the electrostatic repulsion between charged polysaccharides. The lowest water uptake, water retention and swelling were obtained with solutions of CaCl₂, and were related to the known selective afinity of alginate for calcium. Thus, L digitata is especially rich in soluble dietaryfibres, and these have physico-chemical properties characteristic of the polysaccharides present. Water absorption and uptake and swelling can be modulated according lovarious physical and chemical parameters.     

Dietary manipulation of the yield and composition of milk: Effects of dietary inclusions of barley and oats in untreated or formaldehyde-treated forms on milk fatty acid composition

Eight 1st-lactation cows were given four dietary treatments in a duplicated 4×4 Latin square experiment. Diets consisted of hay and soya bean meal together with barley, formaldehyde-treated barley, oats or formaldehydetreated oats (approximately 34:12:54 on a dry matter basis). Barley diets supplied 211 g fatty acids d^?1, oats diets supplied 537 g d^?1. The fatty acid composition (g kg^?1 total fatty acids) for barley diets was: 300 (16:0); 20 (18:0); 150 (18:1); 470 (18:2); 60 (18:3). Corresponding values for oats diets were 180, 20, 390, 380 and 30 g kg^?1. Formaldehyde treatment of the cereals tended to increase milk yield and reduce milk fat content (P<0·01 for barley) but did not affect milk fatty acid composition. Feeding oats in replacement for barley significantly (P<0·05) increased milk yield and lactose yield and reduced milk fat content (P<0·05 for the untreated cereals) and protein contents (P<0·01) without significant effects on milk fat or protein yields. Oats diets led to significant (P<0·001) reductions in the content of 8:0–16:0 fatty acids in milk fat with associated increases (P<0·001) in the content of 18:0 and 18:1. Changes in milk fat content of 18:2 and 18:3 acids were small. The results show the inclusion of oats in the cow's diet to be a means of reducing the saturated fatty acid content of milk fat thereby improving the nutritional value of milk and milk products and their appeal to the health-conscious consumer.