摘要:

AbstractThree compounds containing high percentages of N, P (and S) were prepared, and their degradation studied in both aqueous and soil environments, with particular reference to the appearance of radicals containing these elements in forms normally used by plants. A model is proposed for the degradation of one of these compounds—hexamethyl‐hexaaza‐tetraphosphaadamantane (APA)—which eventually releases orthophosphate and methylamine, presumably a precursor of ammonium. The initial degradation reactions involve hydrolysis through amidophosphites, to phosphite, followed by oxidation to phosphate. The latter reaction appears to be dominantly biological, and should therefore proceed in soil systems. Hexamethyl‐hexaaza‐tetraphosphaadamantane tetrasulphide, a sulphur‐containing compound similar to APA, produced phosphite and phosphate on decomposition, and here the phosphate is probably produced directly by hydrolysis reactions. The third compound, hexamethylaminocyclotriphosphazatriene, has a planar structure in contrast to the cage structures of the other two compounds, and decomposed only very slowly in either aqueous medi

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350202

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractWhite clover (cv. Grasslands Huia), red clover (cv. Norseman) and lucerne (cv. Sabilt) were sampled during primary growth at the flower bud, near full flowering and seeds formed stages in each of 2 years. Each sample was separated into 2–11 plant parts, depending on species and stage of growth, and for each part the in‐vitro true dry matter digestibility, digestibility of cell wall and percentages of cell content, nitrogen, water‐soluble carbohydrate and lignin were determined. Green leaflets of all three species were consistently high in digestibility. The cell wall fraction of green leaflets was less digestible in red clover than in white clover and lucerne. The digestibility of the upper part of the stem of lucerne and red clover was high at the flower bud stage but declined considerably thereafter, whereas the digestibility of the lower part of the stem was much lower at the flower bud stage and declined relatively little. The green leaf stalks and inflorescences were generally rather less digestible than green leaflets and, in lucerne and red clover, more digestible than stems. In white clover the inflorescence stalks were less digestible than the leaf stalks. The digestibility of plant parts was strongly correlated with the proportion of cell content, and less strongly with the digestibility of cell wall. The proportion of cell content was positively correlated with N%, and the digestibility of cell wall was negatively correlated with the proportion of lignin in cell

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350203

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe objectives of this study were to determine whether dietary vicine and convicine were absorbed by rat tissue, and to determine their excretion patterns and/or sites of degradation. Orally administered vicine and convicine were excreted in relatively low amounts via the kidney and faeces. However, no vicine or convicine was detected in the blood, liver, kidney or muscle tissue of rats which had been fed these compounds. In‐vitro studies demonstrated that vicine and convicine were not hydrolysed in liver, kidney, muscle, caecal wall or intestinal wall homogenates. In contrast, digesta samples from the large intestine and caeca were able to rapidly hydrolyse these compounds, with the concomitant formation of new compounds. Digesta from the stomach and small intestine promoted the slow hydrolysis of these compounds, as did fresh faecal samples. These results would suggest that vicine and convicine are absorbed by the rat in only limited amounts, are not hydrolysed by rat tissues, and are rapidly cleared from tissue via the kidney. The bulk of the dietary vicine and convicine are hydrolysed in the large intestine and caecu

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350204

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe venous blood pH, pCO2, lactate, pyruvate and haematocrit responses to an intravenous (i/v) infusion of halothane‐lipid emulsion were assessed in Pietrain, Pietrain X Norwegian Landrace and Gloucester pigs. Halothane‐induced lactacidosis was dose related in the Pietrain (stress sensitive) pigs between 0 and 82 μl halothane kg−‐1, whereas the crossbred and Gloucester pigs did not show any lactacidosis. It is concluded that the i/v halothane test can be used to quantify a stress sensitive pig's reaction to the drug, and that the crossbred pig does not express halothane sensitivity even at a mild level. Carazolol pretreatment in Pietrain pigs increased the halothane‐induced lactacidosis, whereas in a separate study carazolol was found to decrease their rate of post‐mortem muscle acidification. This indicates that halothane activates a different mechanism from stress when inducing lactacidosis in stress se

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350205

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractSixteen laboratories from different countries undertook chemical tests to determine the lysine content of 8 samples of fish meal. The chemical tests were total lysine (gas liquid chromatography or ion exchange chromatography), dye binding capacity (DBC), dye binding lysine (DBL), and reactive lysine (FDNB). The same samples of fish meal were analysed for biologically‐available lysine in four laboratories by chick feeding experiments. Estimates of lysine by all methods except DBC differed significantly between laboratories, but generally meals were ranked similarly by each laboratory. The largest estimate of between laboratory variance, and also the poorest concordance of ranking of the meals by the different laboratories was shown by DBL. The chemical methods for measuring lysine gave means which were significantly different from the bioassay results. However, all the chemical methods gave values which correlated with the bioassay values. The DBC, DBL and FDNB methods gave similarly high correlation coefficients while total lysine was less well correlated. Use of the chemical methods to predict values for biologically‐available lysine gave wide confidence limits which are likely to encompass the variability in the majority of commercial fish meal samples. Consequently none of the chemical methods can be regarded as satisfactory for the purpose of distinguishing between normal commercial samples of fish meals in terms of an absolute content of biologically‐available lysine. The chemical methods may, however, be used in a more limited sense to detect differences in quality between meals of known history without indicating any absolute values for biologically‐available lysine. The dye binding methods appear suitable for process control within a fish meal factory where the analyses are carried out in a single laboratory and the nature of the raw material i

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350206

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractTwo experiments were carried out to investigate the relationship between milk urea content and the heat stability of the protein in the skim milk. In experiment 1, four cows were offered a diet of grass silage with different amounts of hay and a protein concentrate. Although there were individual differences between the cows in the relationship between coagulation time and milk pH, there was a significant correlation between milk urea content and the maximum coagulation time. In experiment 2, two groups of five cows were given a basal diet of hay with a supplement of either barley or soya bean meal. These diets were exchanged weekly over a 3 week period. A significant correlation between milk urea content and maximum coagulation time was observed, and a close relationship between milk urea content and the mean urea content of the blood found. It is concluded that, although milk urea content is not the sole determinant of coagulation time, there is considerable potential for manipulating the urea content of milk in order to increase the heat stability.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350207

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA number of factors involved in the ground drying of sultana raisins to give an acceptable moisture content (‘finishing off’) were studied. Drying responses were related to the potential for water movement from the fruit to the surrounding air as determined by vapour pressure differentials. The direct input of solar radiation energy during the day raises berry temperatures and increases the vapour pressure differential, thus drying occurs. The results show that drying is unduly retarded and non‐uniform when fruit is spread in layers exceeding 25 mm that is, a depth of 3–4 berries. Covering the fruit at night to protect from dew is unnecessary, as the moisture uptake by berries at night is very slow because at the lower temperatures the potential for water movement into the berries is small, and the dew on the surface evaporates once solar radiation increases in the morning. As the season progressed from March to May, conditions for drying became less favourable as both the intensity of the solar radiation and daylength decreased, thus reducing both berry temperatures and the length of drying time per day. These changes were reflected in the measured dryin

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350208

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractConcentration gradients of dry matter, potassium, phosphorus, magnesium and calcium across median transverse slices were measured on a fresh matter basis at intervals during the storage of Spartan apples in either air or 2% oxygen (<1% carbon dioxide) at 1°C. Proportions of calcium declined in the core and increased, during the first 4 months of storage, in the cortex where calcium rapidly became less extractable with 75% ethanol. Proportions of potassium increased in the inner cortex while those of phosphorus increased in the inner cortex and, during the first 2 months of storage, in the core. Proportions of magnesium declined steadily in the peel and outer cortex with corresponding increases towards the fruit centre. These changes were mainly independent of storage conditions and differences in dry matter concentrations. Calcium and magnesium moved to the core region when core browning developed, especially in the air‐stored samples, towards the end of the storage peri

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350209

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe albumin fraction of the cotyledons ofPisumcontains two major polypeptides which together make up 34% (17% each) of the total albumin fraction. Both of these albumins (Mr∼8000 and ∼22000) are cotyledon specific proteins. In manyPisumlines the Mr∼22000 fraction resolves into two components on Na‐dodecylsulphatepolyacrylamide gels. The Mr∼8000 polypeptide was broken down during germination and early seedling growth, indicating that it functions as a storage protein, while the Mr∼22000 polypeptides were degraded relatively slowly. The level of both of these polypeptides was markedly reduced under sulphur deficiency conditions, the Mr∼22000 components being affected to a lesser extent than the Mr∼8000 component. Consistent with this, when [35S]sodium sulphate was injected into the pedicel of control plants during seed development and albumins were isolated at seed maturity, polypeptides of Mr∼8000 and ∼22000 together accounted for a major proportion of the radioactivity in the total albumin fraction. The abundance and relatively high sulphur content of these two albumins could be significant factors in determining the nutritional value o

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350210

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA black gram (Vigna mungo) trypsin inhibitor (BGTI) was purified to homogeneity by ammonium sulphate precipitation, DEAE‐cellulose chromatography and affinity chromatography. The homogeneity of the inhibitor was identified by polyacrylamide gel electrophoresis (PAGE), SDS–PAGE, immunodiffusion and immunoelectrophoresis. The isoelectric point of BGTI was 8.32. The molecular weight of the BGTI was found to be about 12500 by both gel filtration and SDS–PAGE. One mole of the BGTI was found to contain 75 amino acid residues, and it was identified as a glycoprotein, comprising about 18.2% carbohydrate. The BGTI was an uncompetitive inhibitor, stable in the pH range 2–10 and in the temperature range 30–80°C

ISSN:0022-5142    

DOI:10.1002/jsfa.2740350211

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY