摘要:

AbstractIn three separate experiments, the effects of rooting medium pH (pH 4.0, 5.3 and 6.5), root temperature (5, 10 and 15 C) and shoot temperature (6 and 17 C) on the growth, in‐vivo nitrate reductase activity and nitrogen status of winter barley were investigated. Except where temperature was specifically studied, air and/or root temperatures were maintained at 10 C to simulate the typically cool conditions which prevail during the early growing season for cereals in northern Europe.Although growth, nitrate uptake and nitrate reductase activity were markedly affected by variations in temperature and pH. the Nitrogen Response Index, which is the quotient of in‐vivo induced and endogenous nitrate reductase activities in shoot or root material, was unaffected and uniquely reflected the N status of the pl

ISSN:0022-5142    

DOI:10.1002/jsfa.2740500402

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe effect of four types of shaker, extraction time and temperature on the quantity of phosphate extracted by neutral ammonium citrate was evaluated at two research laboratories. Six unprocessed phosphate rocks, and five partially acidulated and four fully acidulated phosphate fertilisers were investigated. Compared with the more than 10‐fold variation in the solubility of the two reactive phosphate rock materials, Sechura and North Carolina, that resulted from using different types of shaker, the solubility of the unreactive phosphate rock materials and the partially and fully acidulated phosphate fertilisers in citrate was influenced to a much smaller degree by the action of the shaker. Sechura was less soluble in citrate that all four unreactive phosphate rock materials when either of the two horizontal shakers were used. This is totally at odds with the documented differences in the chemical reactivity' and agronomic effectiveness of these phosphate rock materials. Not until a wrist‐action shaker was used did the solubility of Sechura and North Carolina exceed that of the unreactive materials and approach that obtained with a full end‐over‐end shake. The neutral ammonium citrate procedure needs to include a more precise definition of the type of shaker and its speed. In laboratories where temperature‐controlled extraction is not available, a 24‐h shake at 20°C using an orbital or end‐over‐end apparatus could be an alternative to the standard 1‐h

ISSN:0022-5142    

DOI:10.1002/jsfa.2740500403

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractDuring the period 1979‐1985, incoming feed ingredients (some of imported origin) for duck diets were screened for their aflatoxin level. As a result. records of aflatoxin data from 533 corn, 88 rice, 136 rice bran, 47 wheat pollard, 207 soya bean meal. 55 copra meal and 166 fish meal samples were obtained.AflatoxinB1was the predominant form, the incidence of samples containing it ranging from 69 to 94%; then accompanied by aflatoxin G1, 37 to 81%: byB2, 33 to 70%; by G2, 13 to 66%.Levels of total aflatoxin>20 μg kg−1were most frequently encountered in corn (71%) and copra meal (58%), followed by soya bean meal (20%), wheat pollard (15%), rice bran (12%), fish meal (10%) and rice (4%). Most feed ingredients contained aflatoxins<100 μg kg−1except in corn of which 202 samples (38%) had a higher level. Corn is concluded to be the main source of alfatoxin contamination in corn‐based mi

ISSN:0022-5142    

DOI:10.1002/jsfa.2740500404

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe major effect ofLactobacillusinoculation on laboratory cassava (Manihot esculentaCrantz) silage was a change from a heterofermentative pattern observed in natural silage to a homofermentation. Small amounts of starter culture (1% v/w) were required to produce a high level of lactic acid (>28 g kg−1DM) and to reach a pH of at least 4. The Gompertz model was used to evaluate the effect of inoculation level on the lactic formation based on kinetic criteria. Also an empirical pH lactic acid correlation was proposed to monitor the progress of ensiling, based solely on pH measurements. The simulation model may be used to improve guidelines for silo safety and to evaluate the effect of lactobacilli inoculant

ISSN:0022-5142    

DOI:10.1002/jsfa.2740500405

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractNear infrared reflectance spectroscopy (NIRS) was evaluated for the prediction of the protein content in samples of grassland herbage taken at different stages of maturity (flowering to fruiting stage) in ‘Dehesa’ zones of Central‐Western Spain. A Technicon Infra Alyzer model 500 scanning monochromator interfaced with a Hewlett‐Packard 1000 minicomputer was used for the study. Protein content was predicted with NIRS data treated as log I/R using six or seven wavelengths. Calibrations were evaluated by comparing Kjeldahl analyses with those predicted by NIRS. The prediction of protein was found to be acceptable, the standard error carying between 0.56 and 0.68% in a range of protein content from 6.76 to

ISSN:0022-5142    

DOI:10.1002/jsfa.2740500406

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe lipid composition of dry edible beans (Phaseolus vulgarisL) was characterised and the variability between four US market classes (navy, dark red kidney, pinto and Black Turtle Soup) was determined. The total lipid content of the beans ranged from 1–8 to 2–6 g per 100 g dry weight. Triacylglycerol esterified sterified glucoside and phosphatidylcholine were identified as the major lipid class components of the neutral lipid, glycolipid and phospholipid fractions, respectively. The fatty acids were highly unsaturated: linolenic acid was the major fatty acid. Three sterols, campesterol, stigmasterol and β‐sitosterol, were identified. The lipid and fatty acid contents of the bean classes were significantly (P<0–05) different. Principal component analysis of the total lipid components resulted in the extraction of four factors, which accounted for 93.3% of the variability of the data set. These factors were characterised as the (I) fatty acid. (II) sterol. (III) lipid class, and (IV) oleic acid

ISSN:0022-5142    

DOI:10.1002/jsfa.2740500407

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe exocellular β‐glucosidases of Candida molischiana andCandida wickerhamiiare able to hydrolyse geranyl, neryl, citronellyl, linalyl and α‐terpinyl‐β‐D‐glucopyranosides. The nature of the aglycone residue greatly affects the rate of hydrolysis. Glucosides with a tertiary alcohol as aglycone residue are more slowly hydrolysed than those with a primary alcohol. The β‐glucosidase fromC molischianais also able to hydrolse α‐L‐arabinofuranosides. This results in the release of monoterpenols from a glycoside extr

ISSN:0022-5142    

DOI:10.1002/jsfa.2740500408

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractDecrease in solubility of volatile compounds (octan‐l‐ol, octanal, ethyl hexanoate, octane and d‐limonene) into a film liner was studied after electron beam irradiation up to 20 Mrad of ethylene vinyl acetate copolymer (EVA) film. The solubility coefficient decreased gradually during ageing despite no change immediately after the irradiation. In all films dosed with 5‐20 Mrad the sorption was depressed about 40% in comparison with the unirradiated one after 4 months. The behaviour was consistent with that of the decay of the radicals in the films. The enthalpy change in sorption (ΔH) was −18.0 kJ mol−1for 5 Mrad ethylene vinyl acetate copolymer film compared with −48.1 kJ mol−1for the unirradiated one. In a homologous series, sorption was significantly depressed with increasing carbon chain length of the volatile compound. The specific sorption depression effect was observed for low polarity compounds such as hydrocarbons, aliphatic esters and d‐limonene. The diffusion coefficient of the sorbed compounds increased about 1.6 times after 3 months when irr

ISSN:0022-5142    

DOI:10.1002/jsfa.2740500409

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe volatiles of six strawberry (Fragaria ananassaDuch) cultivars, both fresh and deep‐frozen, were isolated by direct dichloromethane extraction. Sixty compounds were identified and quantified by GC—MS.Characterisation of cultivars was achieved by applying principal component analysis to the chromatographic data. Great differences were observed. Maxim and Directeur Paul Wallbaum are rather low in volatiles while Gariguette and Tioga are rich in mesifurane (2,5‐dimethyl‐4‐methoxy‐2,3‐dihydrofuran‐3‐one), furaneol' (2,5‐dimethyl‐4‐hydroxy‐2,3‐dihydrofuran‐3‐one) and nerolidol. Esters are the major compounds in Senga Sengana and Vicomtesse Hericart de Thury. This last cultivar is also characterised by high concentrations of γ‐decalactone. Trans‐hex‐2‐enal and hexanal are found mainly in fresh fruits.Determinations of volatiles in stored frozen fruits have shown only slight influence on mesifurane and furaneol while the concentration of nerolido

ISSN:0022-5142    

DOI:10.1002/jsfa.2740500410

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe effects of various postharvest treatments on the sensory qualities of eating‐ripe kiwifruit (Actinidia deliciosavardeliciosa(A Chev) Liang et Ferguson cv Hayward) were compared. When fruit from early harvests (5.3, 6.4% w/v soluble solids (SS) at harvest) were treated with ethylene immediately after harvest, eating‐ripe fruit were more juicy and generally had fewer off‐odours than fruit not ripened by ethylene.A short period (4‐6 weeks) of storage at 0° C was beneficial to fruit quality, particularly when applied to fruit from early harvests. Flavour intensity was enhanced, and off‐flavours, greenness and acidity were decreased.There was variation in fruit quality between orchards. The poorest quality fruit were those from one orchard after storage at 4° C for 4 weeks or at 0° C for 12 weeks prior to ripening. The fruit stored at 4° C was notable for its lack of sweetness and high incidence of earthy off‐flavours. Fruit from both these treatments also had a higher incidence of caramel/burnt sugar flavours than fruit from other treatments.There was no relationship between perceived sweetness and fruit sugar content, SS or sugar/acid ratios, and only a minimal relationship between perceived acidity/tang/sourness and concentrations of each acid. Some suggestions are offered to explain

ISSN:0022-5142    

DOI:10.1002/jsfa.2740500411

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY