摘要:

AbstractFormononetin concentration in red clover herbage, determined by high performance liquid chromatography, was assessed in field, greenhouse and growth cabinet experiments. Formononetin content decreased in Hungaropoly swards from 5.6 mg g−1DM when harvested in early May to 3.5 mg g−1DM when harvested in mid‐June. In the regrowth the sward with the shortest regrowth period had the highest concentration content (6.8 mg g−1). In a pot experiment from vegetative through to the ‘dying inflorescence’ stage, formononetin concentration declined by 57% due to both a reduction in the concentration in stems more than in leaves and an increase in the proportion of stems in the dry matter. A temperature regime of 23/15°C (day/night) advanced flower appearance and adversely affected growth rate compared with 17/13°C. The lower temperature regime resulted in a higher formononetin content in expanded leaves (28% increase, mean of two harvests) and expanding leaves (17% increase). Incubation with β‐glucosidase increased the amount of formononetin extracted in the stems. Phosphate fertiliser reduced the concentration of formononetin, 96 kg P ha−1reducing formononetin content by 32%, relative to red clover grown in soil with a low P content. The results are discussed in the context of the grazing management of

ISSN:0022-5142    

DOI:10.1002/jsfa.2740370402

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe contents of cell wall residue were measured in 14 common feedstuffs used for non‐ruminant farm animals by utilising a technique involving pronase and α‐amylase treatments. Comparison with the contents of neutral detergent fibre (NDF) revealed that the NDF procedure underestimated cell wall contents in the dicotyledonous plant materials. The losses of cell wall material due to the neutral detergent solution were correlated (r=0.931,P<0.01) with the amount of pectic substances present in the cell wall residues of the dicotyledonous plant materials. Cell wall residues were analysed for starch, crude protein, polysaccharides, condensed tannins, sulphuric acid lignin, acetyl bromide lignin, and ash. Condensed tannins in the cell wall residues of sorghum, rapeseed meal and field bean resulted in a large protein contamination (11.3–26.6%) of these residues and to an overestimation of their lignin content. Compositions of polysaccharides are discussed from chemical and nutritonal view

ISSN:0022-5142    

DOI:10.1002/jsfa.2740370403

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe tropical sago palms are increasingly regarded as having a major role as energy crops, but many aspects of them are little known. In this study samples of pith were obtained fromMetroxylon saguRoxb. in West Java and South Kalimantan, Indonesia, and fromArenga pinnataMerr. in West Java. Starch content of pith samples obtained from commercially harvested logs varied between 18.8 and 38.8% (fresh weight) forM. saguand 10.5 and 36.7% forA. pinnata. However core samples of pith obtained in West Java from standing palms ofM. sagusuitable for commercial use or from palms of similar dimensions and appearance, gave a much wider range of starch values; from 0.3 to 32.9% (fresh weight). Starch content was highly correlated with water content. Free sugars occurred at up to 5% (fresh weight) and in samples of very low dry matter content there was more sugar than starch. Predominant simple sugars were glucose, fructose and sucrose. Maltose was not detected. Crude protein and fat were negligible constituents. In addition samples were analysed for NDF, ADF, cellulose, lignin, ash, calcium, phosphorus, sodium and potassium. Pith residues obtained following starch extraction in village mills were found to contain significant amounts of starch.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740370404

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractSources of dietary fibre with a high pentose sugar content have been shown to have the greatest effect in promoting faecal bulking, though no underlying reason for this has been found. Pentose‐containing polysaccharides in dietary fibre are, in isolation, as degradable as other polysaccharides, though their known association with lignin could be important in helping to maintain the structural integrity and hence the bulking ability of a fibre source. Using a modified nylon bag technique, the potential digestibility of fibre prepared from a source rich in pentose sugars (cereal bran) and a source poor in pentose sugars (Swede;Brassica napus, cv. Danestone) was estimated in the pig caecum. Swede fibre was effectively completely degraded (within 18 h) but in bran 100% digestion was not achieved even with extended incubation. Rates of fibre component loss, estimated from material recovered from the nylon bags, showed that different fibre components were degraded at different rates and that the rate of degradation was not always linear. In swede xylose was less readily lost than other fibre components and the rate was non‐linear whilst in bran xylose was preferentially lost and at a linear rate. In bran arabinose was less readily lost. The results showed that the bulking effects of fibre sources with a high pentose sugar content were unlikely to be due solely to pentose content. Differences in rates of digestion suggested that different linkage groups contained within a component may be able to modify the degree of fibre digestion, most probably by the linkage of specific pentosans to lig

ISSN:0022-5142    

DOI:10.1002/jsfa.2740370405

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractTitrimetric, atomic absorption and plasma emission spectrometry methods are compared in the estimation of chromium from an alkaline fusion solubilisation of chromium sesquioxide (Cr2O3) digestibility marker in rat faeces. Considerable differences in the between‐batch precision for the methods were noted. The ferrous ammonium sulphate titration showed the least imprecision (0.67% RSD) compared with 2.1% RSD for the inductively coupled plasma emission spectrometry and 4.7% RSD and 5% RSD for the atomic absorption methods of the nitrous oxide‐acetylene and air‐acetylene flames respectively. The atomic absorption methods were found to be highly sensitive to interferents, chromium oxidation state and changes in flame chemistry with respect to operating condi

ISSN:0022-5142    

DOI:10.1002/jsfa.2740370406

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe nitrate and percentage organic nitrogen contents of 14 vegetable and two arable crops were measured after they had been grown with different levels of N‐fertiliser. Foliage crops always contained substantial quantities of nitrate which increased with increase in the rate of N‐fertiliser application. Grain of legumes and cereals, storage roots of carrots, parsnips and sugar beet, and onion bulbs and leeks contained no detectable amounts of nitrate even when N‐fertiliser application rates were very high. Storage roots of red beet, swede and white turnip contained more than 3 mg NO 3 −N g−1dry weight when grown with exceptionally high levels of fertiliser‐N but contained very little when grown with the optimum amount of fertiliser‐N or less. An equation was developed that linked NO 3 −N to percentage organic‐N for those parts of plants that could accumulate nitrate. It gave good fits to the data from seven crop species grown at a range of different levels of N‐nutrition. It is estimated from the foregoing data and a survey of household food consumption that the average British person consumes about 60 mg NO 3 −N week−1in field vegetables. If N‐fertilisers were withheld consumption would be about 30 mg and if excess were applied it

ISSN:0022-5142    

DOI:10.1002/jsfa.2740370407

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractNear infrared calibrations have been derived and used routinely for a year in the measurement of fat and moisture in air‐dried bread. First and second derivative calibrations were obtained using a Pacific Scientific mark II scanning spectrophotometer on samples sent from all over South Africa to the Wheat Board for analysis. Prediction analysis performed on further bread samples gave standard errors of prediction (s.e.p.) of 0.12% fat and 0.13% moistur

ISSN:0022-5142    

DOI:10.1002/jsfa.2740370408

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractWheat bran was sieved into coarse, medium and fine fractions prior to extraction with tap water. Bran, bran extract and bran residue were analysed for moisture, protein, fat, ash, pentosan and phytic acid. Farinograph measurements and baking tests showed maximum dough resistance and loaf volume of a white flour were both increased by the addition of the residue. Both these parameters were substantially decreased by bran extract and, to a lesser degree, by the bran itself. These findings were common amongst the size fractions although the residue from the coarse bran had the greatest effect on loaf volume and dough properties.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740370409

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThein situde‐esterification of pectin in lime pulp by the action of pectinesterase (PE) has been investigated. It has been shown that the degree of pectin esterification is reduced to about 20% when the pulp is held at pH 8.5 for 90 min. The rate of de‐esterification by the enzymein situis highest when the pH is in the range 7.5–9.0 and the NaCl concentration is 0.1–0.3M. At pH values above 9 chemical de‐esterification becomes important. The activity of extracted lime PE was shown to be almost independent of pH in the range pH 6.0–9.0. It is suggested that the difference between the behaviour of the extracted and thein situenzyme is due to the fact that the latter needs to be solubilised before it can act on some of the pectin in the pulp. In support of this it is found that the proportion of lime PE which can be extracted from the pulp decreases with decreasing pH and ionic strength, reflecting electrostatic binding to th

ISSN:0022-5142    

DOI:10.1002/jsfa.2740370410

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractVarious brining times in saturated salt solution and various drying temperatures were used to produce driedNemadactylus macropterusfillets. The quality of the products was assessed visually before and after reconstitution and also by scanning electron microscopy and isoelectric focusing of the water‐soluble proteins. Product quality deteriorated when brining times exceeded 24 h and also as drying temperatures rose. This was evidenced by poor appearance and reconstitution behaviour, disruption of surface and deep tissue and changes in soluble protein components. An acceptable product was obtained by brining for 8h followed by drying at 50°C. The composition of this product was comparable with that of some commercial dried fish products from South‐east

ISSN:0022-5142    

DOI:10.1002/jsfa.2740370412

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY