摘要:

AbstractFifteen genetically different tea clones showed no variation in their root cationexchange capacity (CEC) values when assessment was made separately on white (including creamy white and cream) and brown (including creamy brown and reddishbrown) portions of roots. But CEC values determined on the whole root system of the same clones were significantly different. This was true for plants varying in age from 8 to 18 months. Clones of Assam types gave lower root CEC values throughout the experimental period than China types, while clones of the Southern form of tea (Cambod) gave high root CEC values initially, which dropped rapidly as the plants became older. Root CEC of different clones was found to be negatively correlated with the brown: white root ratio and with the K: √Ca ratio of the plant tops. Ageing of plants decreased root CEC by increasing the proportion of brown roots, as a result of which the K: √Ca ratio also decreased with

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330402

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractA semi‐micro method is described for the determination by gas‐liquid chromatography (g.l.c.) of galacturonic acid in pectic substances which has been solubilised in aqueous ammonium oxalate. Galacturonic acid, liberated by hydrolysis with polyanhydrogalacturonase [poly‐(1,4‐α‐D‐galacturonide) glycanohydrolase; EC 3.2.1.15] and then converted to the L‐galactono‐1,4‐lactone via potassium borohydride reduction and lactonisation using methanolic hydrogen chloride. The derived lactone was analysed by g.l.c. as the trimethylsilyl derivative, and was easily distinguished from the glucuronic acid reduction product, L‐gulono‐1,4‐lactone. The method was applied to the analysis of pectic materials in leaflets, petioles, and stem of three tropical legumes, and also to the polygalacturonic content of commercial pectin preparations. The possibility of simultaneous determination of starch extracted with

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330403

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractFour mixtures of ground barley and soya bean meal were prepared; the first had no further additive, the second had 10% soya bean oil, the third 0.05% chromic oxide and the fourth both 10% soya bean oil and 0.05% chromic oxide. Each of these mixtures was then dried in three ways: at 30°Cin vacuoand at 60 and 100°C in a forceddraught oven. The total fatty acid content and the fatty acid composition of each sample was determined either by direct esterification of the fatty acids with methanolsulphuric acid or by extraction into chloroform‐methanol followed by esterification with sodium methoxide. When the mixture containing both oil and chromic oxide was heated at 100°C, about 25% of the polyunsaturated fatty acids were lost when they were directly esterified and about 50% when the fat was first extracted from the mixture. It is concluded that this loss is probably due to oxidation of the polyunsaturated fatty acids by the chromic oxide and that the additional loss observed when the extraction method was used is due to partial insolubilisation of the triglyceride by these oxidised fatty a

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330404

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractMeasurements of the specific activity of plants grown in32P‐labelled soils have frequently been used to estimate soil labile phosphorus (L‐values). It is usually assumed that the plant‐P uptake is totally derived from soil‐P. The contribution of seed‐P to plant‐P uptake andL‐values is seldom considered. This paper describes results of an experiment which measured the effects of seed‐P onL‐values and how correction for seed‐P effects may be made when only the tops of plants are analysed.L‐values were obtained from three harvests of ryegrass grown in three soils of very low, low and medium P status (soils I, II and III), containing 4, 14 and 37 mg initial NaHCO3‐soluble P kg−1soil, and supplied with increasing amounts of added P. Ryegrass, supplied with increasing amounts of32P‐labelled31P, was simultaneously grown in P‐free sand, under identical experimental conditions to the soil‐grown plants. The seed‐P in the tops of the sand‐grown plants, at increasing dry matter yields, was calculated and used to make appropriate corrections for seed‐P in the tops of soil‐grown plants. After correction for seed‐P effects,L‐values were reduced at the first harvest by 69% in soil I, 18% in soil II and 10% in soil III, at the second harvest by 27, 11 and 5%, and at the third harvest by 18, 6 and 4%, respectively. Increasing the amount of added P to soil‐grown plants also caused some reduction inL‐values in soil I but the effect was much less in soils II and III. The reduction inL‐values at higher rates of added P in soil I was probably a result of increased P uptake diluting the effects of seed‐P. In the other two soils, plant‐P uptake was much greater, at

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330405

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractDetermination of moisture, crude fibre, fat, ash, total nitrogen and carbohydrates was carried out on almond hulls. The contents of P, K, Mg, Cu, Zn, Fe, Mn, NO3‐ and B were also determined. Amino acid composition was established. The results are compared with analytical data on almond nut

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330406

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractA procedure for the analysis of total dietary fibre (including non‐starchy polysaccharides and Klason lignin) is described. The method consists of extraction of homogenised and/or milled foodstuffs with 80% ethanol and chloroform, and analysis of acidic and neutral polysaccharide constituents, starch and Klason lignin in the residue. Uronic acid constituents were determined by a decarboxylation method, neutral sugar constituents as alditol acetates by a gas‐liquid chromatographic method, starch by an enzymic method, and Klason lignin gravimetrically. The sum of anhydrosugars, anhydrouronic acids and Klason lignin from which the starch content is subtracted provides a measure of the total dietary fibre. The method described is reproducible, fairly rapid and gives informative quantitative characterisation of the fibre constitue

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330407

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe development and refinement of a technique, based on gas chromatography, for the amino acid analysis of fish‐meal are described. Emphasis is placed on streamlining the procedure to facilitate handling samples on a routine basis. Experiments are described from which data are assessed for precision. Results from these experiments confirm that the hydrolysis step contributes significantly to the reduced precision encountered in this type of analysi

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330408

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractA group of ten dairy cows were treated for warble‐fly with the organophosphorus pesticide, crufomate. The persistence of crufomate in the milk of the cows after treatment was determined by gas‐liquid chromatography with a phosphorus‐specific thermionic detector. The mean crufomate concentration in milk dropped below the Codex maximum limit of 0.05 mg kg−1within 24 h of treatment. Crufomate was found to accumulate in the fat fraction of milk, giving rise to a higher concentration of crufomate in milk products, relative to the concentration in who

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330409

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractTests on Golden Delicious and Cox's Orange Pippin apples, evaluated in five and three seasons, respectively, between 1972 and 1980, indicated that method of soil management was still influencing fruit quality 15 years after commencement of the experiment, although to a lesser extent than in the earlier years. In 1973, the soluble solids content, skin colour and yield values of Golden Delicious differed between treatments but no differences were observed for fruit firmness in any of the five seasons when fruit were tested. Acidity values differed in 1972, 1973 and 1980. Overall herbicides gave the highest yields in 1973 and 1975 and the lowest levels of soluble solids. The yield of Cox's Orange Pippin fruit varied considerably between seasons; yields between treatments within seasons were only different in 1975. Correlation coefficients between yield and soluble solids were negative and ranged from ‐0.51 to ‐0

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330410

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractLipoxygenase from the germ of bread wheat was purified to near homogeneity by a classical scheme. After extraction at pH 4.5 from defatted germ, lipoxygenase activity was precipitated by 40% saturation (NH4)2SO4from a 25% saturation supernatant. After dissolution in a phosphate buffer at pH 7 and extensive dialysis against this buffer, the extract was submitted to gel filtration on Ultrogel AcA 34. The final step of DEAE Sephadex A50 chromatography gave three peaks (L1, L2and L3) with lipoxygenase activity. The total yield of the purification procedure was close to 30% and the degree of purification varied from 200 to 300 depending on the fraction considered. The three isoenzymes were also detected by disc electrophoresis using a specific staining method and were isolated by isoelectric focusing in a liquid medium. The molecular weight for each isoenzyme was determined to be 90 000–95 000 by gel filtration and 110 000 by electrophoresis in a gradient of acrylamide concentration. The stability, pH optimum and calcium effect have been studied. L2and L3were less stable than L1. Optimum pH ranged between 6–6.5 and neither isoenzyme activity was affected by calcium ions. L1was twice as active towards β‐carotene as L2and L3for the same level of oxygen uptake, but in comparison to lipoxygenase from horsebean the co‐oxidising power of wheat lipoxygenase was v

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330411

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY