摘要:

AbstractThe digestibility of individual cell wall monosaccharide residues from maize silage (MS) and from maize silage + concentrate (MS+con) diets, was examined in sheep equipped with rumen and duodenal cannulas. Dry matter digestibility was 73.8 and 86.6% in the MS and MS+con treatments, respectively. The overall digestibility of cell walls (CW) and CW monosaccharide residues was not depressed in the MS+con treatment. The values for total CW, CW glucose, CW uronic acid and for total xylose were 68.3, 77.0, 71.6 and 65.2 for MS and 69.4, 80.3, 75.3 and 63.7 for MS+con, respectively. However, the digestion of CW and CW monosaccharide residues in the rumen of the MS+con sheep was reduced and the contribution of the lower tract to the digestion of the potentially digestible CW‐sugar residues was in the range of 15 to 20%. Digestibility of the soluble uronic acid was adversely affected by the concentrate, its digestibility being reduced from 88.6% in the MS to 68.7% in the MS+con treatment. Based on compositional considerations, it is envisaged that the CW structural unit of the ensiled maize plant is made of cellulose fibres enveloped by a thin, poorly lignified and penetrable matrix. The degree of branching of the matrix polysaccharides is low compared with other forage plants. It is suggested that the above mentioned properties significantly contribute to the high quality of the ensiled maize plan

ISSN:0022-5142    

DOI:10.1002/jsfa.2740360302

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractBuffer‐soluble seed proteins of 12 varieties of winged bean (Psophocarpus tetragonolobusL.) were separated by ultrathin‐layer isoelectric focusing (IEF) and sodium dodecylsulphate electrophoresis(SDS‐PAGE). Whereas the molecular weight spectra of the proteins obtained by SDS‐PAGE were identical for all varieties studied, the IEF patterns showed variety specificity for each sample. Most of the variety specific protein bands were identified as glycoproteins. The zymograms of the isoelectically focused trypsin inhibitors were variety specific in both activity and isoelectric point distr

ISSN:0022-5142    

DOI:10.1002/jsfa.2740360303

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThe response of winter wheat to surface waterlogging in monoliths of clay soil in lysimeters was studied. The treatments, selected as corresponding to the most extreme likely in Britain, were: 5 days of waterlogging in October between germination and emergence; 42 days of waterlogging during tillering in January and February; and 21 days from mid‐April during stem elongation. These treatments were used singly and in all combinations and were compared with a freely‐drained control. During waterlogging, the oxygen concentration in the soil declined most rapidly when the soil was warmer (in October and April) and at the shallower depths (5, 20cm): also, a decrease in soil solution nitrate was accompanied by an increase in nitrous oxide evolution. Pre‐emergence waterlogging restricted plant population to 35 m−2compared to 338 m−2under free drainage. Subsequently, compensatory growth resulted from diminished interplant competition for nitrogen, water and light: a greater proportion of tillers survived and the flag leaves were larger, although ears at harvest were fewer in all treatments waterlogged before emergence. After waterlogging during tillering, grain loss was accounted for entirely by a decrease in the number of ear‐bearing tillers. After waterlogging during stem elongation, yield losses were associated primarily with fewer grains per spikelet. Grain yield was depressed by about 4–12% after single waterloggings, by 20% after any two waterloggings, and by 32% when plants were waterlogged on all th

ISSN:0022-5142    

DOI:10.1002/jsfa.2740360304

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractA fast, accurate method for determining total sugars in sugar crops was developed. Sugars were quantitatively removed from the tissue by homogenisation and hot water extraction. Lead acetate was used to clarify the extract by precipitating any interfering non‐sugar reducing substances. Lead was then removed by precipitation with sodium oxalate. The extract was hydrolysed to convert sucrose into glucose and fructose. After neutralising, total sugars were determined as total reducing sugars by automated colorimetry using a Technicon Auto‐Analyzer. Data presented show optimum conditions for extraction, clarification and acid hydrolysis of sucrose to reducing sugars. The method has a precision of 2.1% coefficient of variation for 10 consecutive analyses of a sweet sorghum sample with a mean total sugar concentration of 14.2±

ISSN:0022-5142    

DOI:10.1002/jsfa.2740360305

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractOne hundred groundnut germplasm accessions were analysed for their oil content by the standard Soxhlet extraction procedure using petroleum ether: the results were compared using functional analysis with those obtained with a commercial nuclear magnetic resonance (n.m.r.) spectrometer. On another 78 experimental samples, oil content was first obtained using the n.m.r. method and the Soxhlet values were predicted using the above functional relationship. On the 78 samples the predicted values were highly correlated (r=0.972) with those obtained by Soxhlet extraction. The n.m.r. method is rapid, easy, acurate and non‐destructiv

ISSN:0022-5142    

DOI:10.1002/jsfa.2740360306

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractRapid post‐harvest physiological deterioration of cassava roots (Manihot esculentaCrantz) appears to be due essentially to wound responses, comparable to those observed in other plant storage organs. The wound responses observed include: increased activity of phenylalanine ammonia lyase, an enzyme associated with phenol biosynthesis; increased activity of peroxidase and polyphenol oxidase; formation of phenols/polyphenols including leucoanthocyanidins, catechins, sco‐poletin and condensed tannins, and often the formation of a wound periderm. In cassava, the responses did not remain localised at wound surfaces in roots when held at low storage humidity but spread through the roots causing a discolouration of the vascular tissue and storage parenchyma. Roots stored at high humidity showed a more typical wound response with localised production of phenols and periderm format

ISSN:0022-5142    

DOI:10.1002/jsfa.2740360307

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractA critical study was made of a number of lipid extraction methods on stabilised brown fish meals and on white fish meal. By analysing the lipids it was shown that in all procedures proteinaceous material was extracted and an attempt was made to correct for this non‐lipid material. On the basis of the results obtained it seemed that the Bligh and Dyer method gave the highest yield of lipid. In addition it was found that the EEC procedure needed the application of a correction factor to account for the losses sustained in the hydrolysis ste

ISSN:0022-5142    

DOI:10.1002/jsfa.2740360308

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThe impact of N‐fertilisation level on protein content, total fatty acid (TFA) content and major fatty acid composition of barley grains (cv. Eldorado), grown in a replicated field trial, was investigated. Increasing amounts of N‐fertiliser, applied at several stages during the growing season, resulted in a higher protein content and a very slightly lowered TFA content in the grains. Protein and TFA contents were negatively correlated (r=‐0.4685). Minor changes of fatty acid composition were found in the decrease of the oleic acid (C18:1) proportion (r=‐0.8376) and in the increase of the palmitic acid (C16:0) proportion (r=0.7273). The stearic acid (C18:0) and the linoleic acid (C18:2) proportions were also affected, however, no significant linear correlations with the total N‐fertiliser level were obtained. The slow increase in the linolenic acid (C18:3) proportion (r=0.5674) was too small, compared to the residual variance, to be significant. TFA content was positively (P<0.001) correlated with the oleic acid proportion, and negatively (P<0.001) with the palmitic acid proportion. These data suggest that the application of higher amounts of N‐fertiliser slightly decreases the total fatty acid content of barley grains, probably due to a decreased synthesis of oleic acid, precursor of the unsaturated C18 fatty acids. The result is a relative increase in pa

ISSN:0022-5142    

DOI:10.1002/jsfa.2740360309

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractLipase has been purified from the hepatopancreas of oil sardine (Sardinella longiceps) by defatting, water extraction, ammonium sulphate fractionation and chromatography on DEAE Sephadex and Sephadex G‐100. The preparation was homogeneous on polyacrylamide disc gel electrophoresis and on gel filtration through Sephacryl S‐200. The enzyme showed a molecular weight of 54000±57000 with 6.1% of carbohydrate. The pH and temperature optima of purified sardine lipase were 8 and 37°C respectively. Sardine lipase remained stable up to 45°C (15 min) and in the pH range 5 to 9.5. The Kmvalues obtained for the substrates tributyrin and triacetin were 4 × 10−2and 30 × 10−2, respectively. The effect of halogens and various metal ions on sardine lipase activity, substrate specificity, amino acid and carbohydrate composition are a

ISSN:0022-5142    

DOI:10.1002/jsfa.2740360310

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractA selected panel, trained in sensory procedures, used a previously developed vocabulary to profile the aromas of six ground coffees. The same coffees were also examined by a different panel of assessors not familiar with coffees, using free‐choice profiling and, on a separate occasion, similarity scaling procedures. The data from the three experiments were independently subjected to the appropriate statistical techniques to produce two‐dimensional diagrams showing the interrelationships of the samples. All three procedures produced similar information both in respect to the way the coffees grouped and differed from one another. The paper concludes by discussing the assessor variation associated with each of the procedures and shows that free choice profiling compares very favourably with the other

ISSN:0022-5142    

DOI:10.1002/jsfa.2740360311

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY