摘要:

AbstractA comparison was made between the effects of three consecutive years of either direct drilling or ploughing, on the distribution of extractable soil phosphate and potassium, and the distribution of roots of a spring barley crop in the upper 20 cm of the soil. Samples were collected from a clay soil (Evesham series) in June 1975 when the crop was mid‐way through the phase of stem extension (Feeke's growth stage 7–8). With ploughing, the concentration of nutrients was approximately uniform to the maximum depth of cultivation (20 cm). With direct drilling there were markedly higher concentrations of phosphate and potassium in the upper 5 cm of the soil, but at depths between 10 and 20 cm the concentrations of potassium, and particularly phosphate, were lower than with ploughing. Root weight and length, per unit soil volume, in the upper 5 cm, were also greater with direct drilling than with ploughing. However, the more superficial distribution of phosphate and of roots with direct drilling did not restrict phosphate uptake by the crop, despite the dry summer. The results are discussed in relation to factors contributing to differences in the distribution of nutrients and roots in land receiving contrasting cultivations, and possible consequences for crop growth are indica

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290302

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractManganese in lucerne (Medicago sativaL.) exists as a cationic complex of low molecular weight. It migrates as a single band on paper electrophoresis, cation exchange chromatography and gel exclusion chromatography. It exhibits no strong association with protein. The complex tends to be unstable in alkaline solution.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290303

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractUnripe Cavendish banana fruits were stored at 5–7°C under normal or 0.14 normal atmospheric pressure for two weeks, with or without a continuous supply of ethylene, prior to ripening at 20°C. Pulp/peel ratio, colour index and production of volatile were measured following prestorage at chilling temperature, and after reaching ripeness at 20°C. CO2and C2H4production were also measured at 20°C. The results show that green fruits had lower pulp/peel ratios than treated green fruits while the reverse was true following ripening at 20°C. Yellow colour development was retarded by 5°C pretreatment, and low pressure storage had no noticeable effect on colour index. Prestorage at 7°C, however, improved colour development slightly. Acetates, butyrates and alcohol produced by fruits prestored at chilling temperature and 0.14 normal atmospheric pressure showed both qualitative and quantitative differences compared with those produced by non‐chil

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290304

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractAn apparatus for sampling and trapping the air in potato stores was developed and used to study the accumulation of volatile substances in a modern large store over a season. Isopropyl‐N‐(3‐chlorophenyl) carbamate (CIPC, chlorpropham), together with two isomers of tetrachlorobenzene, was present at all times after its application as a sprout suppressant, although the concentration fell with time. None of the known volatile substances associated with potatoes nor metabolites of isopropyl‐N‐(3‐chlorophenyl) carbamate was detected. 2,3,4,6‐Tetrachloroanisole and pentachloroanisole were present at all times even before the store was filled, but did not reach levels at which taint occurred in the processed products. Eight commercial samples of isopropyl‐N‐(3‐chlorophenyl) carbamate were analysed and the only major variation found was the presence of isopropyl‐N‐phenyl carbamate (IPC, proph

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290305

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe protein quality of newly evolved high‐yielding Indian varieties of rice, namely, Improved Sabarmati, Pusa 2‐21, Jaya and Padma has been evaluated and compared with an old existing popular variety i.e. Basmati‐370. All the new varieties were found superior in their limiting amino acid content (lysine, tryptophan and methionine) and the ratio of various fractions of proteins. The animal feeding tests for biological value (BV), true digestibility (TD), net protein utilisation (NPU) and utilisable nitrogen (UN) also showed their superiority over Basmat

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290306

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe protein quality of common Indian pulses, namely soybean (Glycine max), red gram (Cajanus cajan), green gram (Phaseolus aureus) and black gram (Phaseolus mungoRoxb) has been evaluated with respect to their limiting amino acids (methionine and tryptophan) and the protein fractions. Feeding experiments conducted on wistar albino rats showed a significant improvement in the biological value (BV) on rice‐pulse mixed diets as compared to rice alone. However, significant reduction in the true digestibility (TD) of rice‐pulse diets was observed when rice was mixed with black gram and red g

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290307

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractA method has been developed for the separation, identification and estimation of six mycotoxins in foods at the μg kg−1level. The food is extracted by using aqueous acetonitrile and the extract is then washed with 2,2,4‐trimethylpentane and any mycotoxins re‐extracted into chloroform. The extract is then purified using grooved t.l.c. plates coated with silica gel. After chromatography, any fluorescent bands are removed and examined by h.p.l.c. using a fluorescence detector. The method has been tested using a range of foods including total diet samples. Recoveries at twice the detection limit varied from 40

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290308

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractA method is described for the estimation of 3 u.v.‐absorbent mycotoxins in foods by using semi‐preparative and analytical h.p.l.c. columns. The foodstuff is extracted using aqueous acetonitrile and fatty matter is removed from the extract by partition into 2,2,4‐trimethylpentane. Mycotoxins present in the fat‐free extract are then back extracted into chloroform and separated into two fractions on a silica gel column using (a) diethyl ether and (b) chloroform: methanol. Further purification on a semi‐preparative alumina column is described prior to measurement of mycotoxin content on analytical h.p.l.c. columns. Recoveries of zearalenone, patulin and penicillic acid added at 2 to 4 times the detection limit to samples of meat, dairy products and cereals ranged from 5

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290309

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe thermal precipitation and denaturation of conalbumin was studied separately at different pH values, low concentrations of an anionic detergent and salt concentrations relevant to food products. Sodium dodecylsulphate (SDS) was used as a model detergent and was found to lower the limit for thermal precipitation from pH 10–11 to pH 6–8 leaving a neutral pH region open for heat processing without any decrease in solubility. This protection against precipitation took place at the expense of a reduced thermal stability of conalbumin. Analysis at linearly increasing temperatures was shown to be a productive method to study the coupling between the thermal precipitation and denaturation processes. This coupling was examined at two heating rates, 10 and 1.25°C/min, respectively. Two types of precipitation behaviour were identified, a rapidly and a slowly sedimenting one. At the lower heating rate and under conditions where rapidly sedimenting precipitates were formed there was a close correlation between precipitation and denaturation. The precipitation was, however, always completed prior to denaturation. When approaching conditions where no precipitation took place, which also implied a successive transition towards slowly sedimenting precipitates, the precipitation process became delayed compared to denaturation. Precipitation could thus be registered at temperatures far above those of complete denaturation. The precipitates formed showed a considerable variation in particle size and water holding capa

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290310

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe kinetics of heat inactivation and reactivation of peroxidase were examined in extracts of carrots, spinach and apricots. The enzyme from carrots was the most heat‐stable and showed the highest reactivation during storage whereas the peroxidase from apricots was the most heat‐sensitive and showed no reactivation during storage. Higher rates of reactivation were generally observed for samples stored at ‐ 5°C compared to those stored at 4 and 18°C. The optimal pH for reactivation of peroxidase from spinach and apricots was pH 8.0. The presence of sodium chloride resulted in higher rates of reactivation during storage whereas sucrose had no significant

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290311

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY