摘要:

AbstractIn an agronomic experiment, perennial ryegrass was grown with four rates of fertiliser N + K at 21 sites in England and Wales. Herbage from two successive harvests at 14 of the sites has been examined for contents of N and S and of other mineral elements in relation to the nutrition of both the crop and ruminant animals. The highest rate of fertiliser application (125 kg N+77.5 kg K/ha harvest) resulted in contents of total N greater than 4% at five sites at the second harvest, but nitrate‐N reached levels that might be toxic to livestock (>0.35%) at only two sites. There was no evidence that supplies of S from soil and the atmosphere were inadequate for crop growth, or that the contents in the herbage were insufficient for ruminant animals, even though no S was supplied as fertiliser. On the contrary, in many samples, the content of S was so high as to constitute a potential hazard for ruminant animals through impairment of Cu availability. Values for the ratio total N: total S, which ranged from 3.2 to 15.6:1, generally increased with increasing rates of fertiliser. The concentrations of sulphate‐S in the herbage were generally high and represented between 19 and 78% of the total S. The content of Mg was only slightly affected by fertiliser N + K, but the ratio K: (Ca + Mg) increased markedly with increasing rates of fertiliser. At several sites the ratio exceeded 2.2:1, the value above which there is an increasing risk of hypomagnesaemia in ruminant animals. The sum of the concentrations of the cations Ca + Mg + K + Na in the herbage increased as the concentration of N increased, and there was a similar though less marked relationship between organic anions and total N in the herb

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290102

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe plant processes of copper uptake by roots of perennial ryegrass and transport to shoots were examined after plants had been grown in either solution culture, or in soil, with wide ranges of copper additions. Although contents of both shoots and roots of plants grown in solution culture and in soil increased with increasing addition of copper, the increase in roots was very much greater than that in shoots in which the range of concentrations was small. A large proportion of uptake was retained by roots even when they had been damaged by toxicity. Copper accumulated in roots of plants grown in solution culture was not available for transport to shoots after further supply had been withdrawn, and large proportions of the retained copper were associated with cell walls. It was concluded that roots of perennial ryegrass restrict the movement of copper along the pathway soil‐plant‐ani

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290103

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractVolatile fatty acids (VFAs) were measured in slurry stored in farm and laboratory conditions. All slurries from farm sources contained VFAs; acetic acid was predominant, followed by propionic, n‐butyric, iso‐butyric, iso‐valeric and n‐valeric. On average, pig slurry contained more total VFAs than did cow slurry. VFAs persisted in anaerobic conditions but decomposed rapidly when air was passed through slurry in laboratory experiments; decomposition was slower when air was passed over the slurry surface. Very little VFA formed when anaerobic conditions were re‐imposed on aerated slurry unless glucose or protein hydrolysate was added. The pH of slurry was increased by passing air or nitrogen through it and decreased by addin

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290104

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe lipids from four commercial fish meals (white fish, South African, Herring, and Bermuda) were extracted with methanol‐chloroform and their component acids examined by gas‐liquid chromatography (g.l.c). In addition to saturated, monoene, and polyene acids, three phytol‐based acids(1‐3)are present as minor components. There is, however, no evidence for the presence of furan‐containing fatty

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290105

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractChanges were studied in the bulk protein of tobacco leaves, lucerne shoots and sunflower‐seed kernels subjected to aerobic autolysis at room temperature. Bulk‐protein fractions from cigar and from commercial sunflower‐seed meal were also examined. Quinic acid, released by cold alkaline hydrolysis, was used as a measure of binding of chlorogenic acid residues to the proteins. On aerobic autolysis, the proteins of the leafy materials underwent some proteolysis; chlorogenic acid residues became bound to the protein, with concomitant diminution of free chlorogenic acid. The proteins showed browning, increased ultraviolet absorption and diminished content and “chemical availability” of lysine. However, during aerobic autolysis, the bulk protein of sunflower‐seed kernels did not couple appreciably with the chlorogenic acid congeners present; the above accompanying phenomena were also largely absent. It is concluded that, when protein‐rich plant materials are to be fed to monogastric animals, and particularly when their lysine content is critical, more attention should be paid to effects of the polyphenols and polyphenol oxidases present in the o

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290106

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractValencias on five rootstocks were harvested at approximately monthly intervals between December and May for four years. Palatability was assessed by a taste panel (mean of 19 tasters per panel) and related by regression analysis to easily measured indices such as % soluble solids, titratable acidity and juice content. Only soluble solids and juice content were useful in predicting the mean rating of the taste panel (r2= 0.42 and 0.35 respectively). Percentiles of tasters' scores for juice with similar values of the indices were more accurately predicted by the indices than by simply using the mean panel ratings (r2up to 0.81). Regression lines giving mean panel score for different per cent taster response for juice and soluble solids content are presented.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290107

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe protein of distal halves of barley kernels or small meal samples was extracted with ethanolic sodium hydroxide solution. After dilution, the protein content was estimated with a spectrophotometer by measurements at 215 and 225 nm. The tryptophan content was estimated from the same extract by a spectrophotofluorimeter. The methods showed high correlations with those used for control. The presented methods can be used in screening kernels in segregating ears or selecting single plants.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290108

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractA study was made of the conditions for determining all thiol (SH) groups and disulphide (S—S) bonds in wheat flour and dough. Thiol groups were determined by amperometric titration with Ag2SO4, the flour or dough which contains proteins and peptides being suspended in a solution of 6 m urea and 10−4M sodium dodecyl sulphate (SDS). The potential of the platinum electrode was −0.24 Vvscalomel reference electrode. Disulphide bonds were determined in two ways: (a) Using an excess of Ag2SO4in the presence of 9 M urea; when the reaction was finished, the excess Ag2SO4was removed by adding an exact quantity of glutathione. The glutathione which remained after binding the Ag2SO4excess was determined by amperometric titration with a 5.10−5M Ag2SO4solution, (b) Determination after reduction with NaBH4; the disulphide bonds were reduced to thiol groups and the total amount of thiol groups was determined with Ag2SO4. The results indicated that wheat flour contains 5–7 μmol SH‐groups, which is about six times the level found by previous workers, and 11‐18 μmol disulphide bonds per gram flour. A correlation with baking quality w

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290109

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe competitive nitrosations of pyrrolidine,p‐cresol and L‐cysteine hydrochloride were studied in aqueous solution. The reactions were studied at pH values 3.0, 5.0 and 5.5 and at temperatures 20, 37 and 120°C, conditions which simulate those found in meat during processing, storage, cooking and gastric digestion. The formation of N‐nitrosopyrrolidine was observed only in the reactions carried out at 120°C, subject to a detection limit of 0.2 parts/106. At this temperature the effect of L‐cysteine hydrochloride alone and in combination withp‐cresol is to enhance the rate of N‐nitrosopyrrolidine formation at pH 5.0 but to inhibit it at pH 3.0. In reactions at 20 and 37°C, where N‐nitrosopyrrolidine was not detected, the rate of C‐nitrosation ofp‐cresol to giveo‐nitro‐p‐cresol is inhibited in the presence of L‐cysteine hydrochloride a

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290110

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractResults are presented for the levels of sodium, potassium, calcium, magnesium, iron, copper, zinc, lead and arsenic in 144 lager samples. The average and range of each of the metals, in mg/litre, are as follows: sodium 58(15–170), potassium 362(253–680), calcium 46(10–135), magnesium 82(34–162), iron 0.12(0.04–0.44), copper 0.11(0.01–0.41), zinc 0.06(0.01–0.46), lead all samples below 0.06, arsenic all sampl

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290111

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY