摘要:

AbstractInterest in potassium (K) manuring has decreased in recent years because applying K leads to no environmental problems, few soils are K deficient and K is cheaper than N. However, fresh K optimises yields, especiatly with high‐yielding crops and through its interaction with N, and K residues benefit crops in a way that often cannot be offset by fresh K. To achieve a rational basis for K manuring, the various sources of K and demands for K by the crop must be considered and used, together with soil and crop analyses, to predict K fertiliser requirements. K should be applied annually, perhaps as an NK compound, on light‐textured soils. On heavier soils it can be applied at any convenient point in a rotation, probably just before the most K‐sensitive crop is grown. Applications should match or slightly exceed crop requirements. There is little to gain from omitting K and every reason, both economic and agronomic, to include it. Such a rational policy will provide due reward in current crop yields and quality and in future soil product

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460102

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460103

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract2,6‐Dibromophenol was identified as the cause of an iodoform‐like off‐flavour in the endeavour prawn,Metapenaeus endeavouri. In prawn meat this compound was detected by its characteristic flavour at a concentration of only 60 ng kg−1. However, quantitative analyses by gas chromatography‐multiple ion monitoring‐mass spectrometry of extracts of whole off‐flavoured prawns showed that, in some samples of this species, the concentration of this compound exceeded 200 μg kg−1. In addition, marine algae and bryozoa, which probably contribute to the diet of the endeavour prawn, were shown to contain the off‐flavour compound in comparable concentrations. 2,6‐Dibromophenol was also identified as the cause of an iodoform off‐flavour in the eastern king prawn,Penaeus plebejus. Furthermore, this compound was shown to be present in relatively low concentrations in five species of prawn not usually affected by this problem. 2‐and 4‐Bromophenol, 2,4‐dibromophenol and 2,4,6‐tribromophenol were also identified in all species of prawn examined. Handling and processing procedures which could reduce the severity of the off‐flavour in s

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460104

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThis study examined whether delayed bleeding at slaughter affected the overall appearance and residual blood content of beef. Three muscles were analysed for residual blood content, and when delayed bleeding was performed only the forequarter muscle showed high blood levels indicating that engorgement occurred where blood had gravitated within the carcass. Electrical stimulation of the carcass immediately before delayed bleeding did not expel any of the retained blood. In terms of the overall appearance of the carcass, the worst sites for blood engorgement were the thymus, lungs and subcutaneous fat at the brisket and neck. A trial was also conducted which showed that inducing a cardiac arrest helped to reduce the expression of bruises inflicted at stunning or slaughter.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460105

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractSeveral hexaploid derivatives of wild emmer wheatTriticum dicoccoidesL developed in Israel possessed a high molecular weight glutenin subunit having slightly lower mobility in sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE) than theGlu‐Alasubunit of the reference cultivar, Hope. The lower mobility subunit appears to have been inherited from the tetraploid wild emmer G25, a parent used in developing the derivatives. Two‐dimensional electrophoresis indicated that the lower mobility subunit from the wild emmer G25 and from the derivatives consisted mainly of two components more basic than the components of theGlu‐Alasubunit from the 20 reference cultivars examined. In 49 wild emmers examined by SDS‐PAGE, at least seven different mobilities were distinguished among the least mobile subunits. Three emmers had a subunit of comparable mobility to the G25 upper band, and one had a subunit of similar mobility to theGlu‐Alasubunit. Two‐dimensional electrophoresis confirmed the match of the former three, but demonstrated a difference between the isoelectric point of the latter and theG

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460106

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractTea was processed from leaves grown on un‐shaded, artificially shaded andGrevillea robustaCunningh shaded plots at four different levels of nitrogen application (0 to 270 kg ha−1year−1). Tea grown under artificial shade produced black tea with higher theaflavin and reduced thearubigin concentrations and with a better flavour index and tasters' evaluation than did tea grown without shade. The heavier (artificial) shading gave teas better than those derived fromGrobusta shaded teas. No statistically significant effects on the caffeine contents were observed. The data presented suggest that the removal of shade from tea gardens leads to a loss in quality. The need for a more complete economic evaluation is disc

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460107

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractSome nutritional and anti‐nutritional characteristics of mucuna (Mucuna utilis(Wight) Burck) bean seeds were studied. The mature seeds contained 264 g crude protein, 63 g crude fibre, 41 g crude fat, 37 g ash and 595 g carbohydrates kg−1DM. The essential amino acid profile compared well with the FAO/WHO scoring pattern except for a deficiency of sulphur‐containing amino acids. Mineral composition was similar to those reported for most tropical grain legumes.Raw mucuna seed samples contained moderately high levels of anti‐tryptic activity (2170 trypsin units inhibited g−1DM), but this was completely destroyed by cooking. The other anti‐nutritional factors (phytate, cyanide and tannins) are probably of little nutritional significance provided that the beans are properly processed. The in‐vitro protein digestibility of raw and cooked beans were 71·5 and 80·3 %, respectively. In view of the high L‐DOPA contents reported in some mucuna cultivars, overconsumption of mucuna beans should be viewed with some caution until suitable processing meth

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460108

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA method for preparing dry powders from fish muscles is described. The muscle dry powders (MDP) were extracted with low ionic strength buffer and compared with sarcoplasmic extracts of raw muscles by isoelectric focusing on ultra‐thin layer (100 μm) polyacrylamide gels. The protein patterns of MDP extracts corresponded to the patterns of the acidic proteins of raw muscle extracts. Because of the species specificity of the patterns, MDP can be used as reference material for fish species identification.The acidic proteins remained extractable after storage of MDP for several months at room temperatu

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460109

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe coalescence stability of protein‐stabilised emulsions was estimated by measuring the degree to which the oil content could be extracted by hexane. The hexane extraction method is an empirical one but it correlates well with both an absolute method, such as increase in droplet size, and with another ‘accelerating’ technique, oil separation by centrifugation. Moreover, the hexane extraction method is capable of measuring coalescence stability over a wide range of instability, whereas the centrifugation method only provides information about the final stages of emulsion instability.Among the proteins studied, caseinates were generally the best stabilisers, especially at pH 6. Soya proteins gave rise to emulsions of minimal stability, whereas whey protein concentrate and blood plasma resulted in emulsions of medium stability.The coalescence instability of the protein‐stabilised emulsions, viewed overall, was significantly and positively related to the droplet size, the degree of flocculation and the amount of protein in the membrane. High values of these emulsion parameters were due mainly to frequent recoalescence and bridging during emulsification. To minimise these effects emulsifying conditions creating high protein: surface area ratios should be used, as well as proteins that quickly change their conformation at an interface and have low aggregation numbers in s

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460110

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractPolyphenoloxidase (EC 1.10.3.1) in eggplant (Solatium melongenaL) was purified by ammonium sulphate fractionation, DEAE‐Cellulofine and DEAE‐Toyopearl chromatography and Sephadex G‐100 gel filtration. The enzyme was purified about 110‐fold with a recovery of 5%. The purified enzyme more quickly oxidised chlorogenic acid (5‐caffeoylquinic acid, IUPAC) than 10 other substrates used. The Kmvalue for the enzyme was found to be 0·50 mM with respect to chlorogenic acid; the optimum pH of the enzyme was about 4 with enzyme stability between pH 5 and 8. The enzyme was completely inactivated after heat treatment at 75°C for 30 min or 80°C for 5 min. Sodium metabisulphite, potassium cyanide and sodium fluoride markedly inhibited the enz

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460111

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY