摘要:

AbstractQuantitative methods are presented for distinguishing rheologically‐important thiol and disulphide groups of wheat dough from those which are unimportant. The determinations are carried out in the farinograph and the use of extracting solvents is completely avoided. Dithiothreitol andN‐ethylmaleimide are used as respective titrants of disulphide and thiol groups.Less than 4% of the total disulphide is involved in determining development time; 11 to 13% is involved in the resistance to mixing. About 25 to 35% of the total thiol is involved in both development and tolerance to mixing. A positive relationship between the content of rheologically‐important disulphide and development time has been shown in flours from several varieties of wheat.It was further found that the addition of iodate can rapidly increase the resistance to mixing of a partly reduced dough.The nature of the rheologically‐important thiol and disulphide groups is discussed in relation to current knowledge of their distribution among large and small molecules, their importance in maintaining structure and their involvement in thiol‐disulphide exchange reactions duri

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250102

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractChanges in the amino acid fraction of buffered extracts of cod muscle during incubation in the presence of α‐ketoglutarate have been studied using a14C‐labelled amino acid mixture. The patterns of radioactive amino acids pre and post incubation suggest that transamination reactions are responsible for marked changes in the levels of aspartic acid, glutamic acid, alanine, valine, leucine and iso‐leucine. No changes were noted in the levels of threonine, serine, proline, glycine, lysine and arginine. Slight falls in the concentration of tyrosine and phenylalanine were seen after extended incubation

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250103

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe kinetics of radioactive SO2uptake byS. cerevisiaevar.ellipsoideus, the effect of temperature on the uptake, the irreversible thermal inactivation of the uptake and the specificity for the molecular form of SO2in the process indicate that mediated transport is operative in this uptake. Both the transport and toxicity of SO2in this yeast are strongly pH‐dependent and the dependence is based on the determining effect pH exerts on the distribution of the forms which SO2assumes in solutio

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250104

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractFusel oils from Australian grape wines (Vine sp.Vitis vinifera) have been found to consist substantially of ethanol,n‐propanol, isobutanol (2‐methyl‐1‐propanol), isoamyl alcohol (3‐methyl‐1‐butanol) and active amyl alcohol (2‐methyl‐1‐butanol). In addition there are present large numbers of aliphatic esters, believed to be of considerable importance to grape brandy and spirit flavour and quality. The quantities and occurrence of these esters have been found to follow a systematic pattern. The major esterified alcohols are related to the free alcohols present and the major esterified acids occur as a series of acids of even carbon number with a maximum concentration at then‐decanoic acid. These relationships provide a basis for calculating the approximate ester com

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250105

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractMethods for the determination of 2–6‐diaminopimelic acid (DAPA) and 2‐aminoethylphosphonic acid (AEP) are described. The DAPA method consists of hydrolysing the sample, its purification on charcoal columns, separation of DAPA from proline on columns of an anionic resin, and the determination of DAPA with acid ninhydrin. The AEP method consists of hydrolysing the sample with hydrochloric acid, separation of AEP from inorganic phosphate on columns of a cationic resin, hydrolysis of the P‐C bond in AEP with perchloric acid and the determination of AEP as phosphate. Examples of analysis of foods, gut contents and microbial fractions ar

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250106

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractExperiments were conducted to study the effect of killing procedures on the biochemical metabolites of broiler chicken breast muscle.The degree of struggle at death profoundly affected the onset ofrigor mortisboth in intact carcases and in muscles stored off the bird. Evidence was obtained that the amount of ATP present in the muscle, and hence the time of onset ofrigor, could be estimated by measurement of the pH value of the muscle.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250107

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractAmylase isozymes were studied in six varieties ofAvena sativaL. using agar gel electrophoresis. Three distinct zymograms were detected in aqueous extracts of endosperm of 4 to 5‐day old seedlings. No intravarietal variation was observed. These results indicate that amylase zymograms may be useful markers for helping in the identification of oat varieties. Using the varieties Maris Tabard and Maris Titan it was found that all the isozymes in 4 to 5‐day old seedlings, except one, had the properties of α‐amylase. The zymograms of extracts from ungerminated grains of these two varieties, although apparently identical to those of 4 to 5‐day old seedlings, differed in that all the α‐isozymes in the former were found to be heat labile whereas in the latter they were

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250108

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe sorption of iodide by several soil component materials was examined over a range of pH values and compared with sorption by a surface soil. A compost, prepared from grass roots which had been allowed to decompose for 24 weeks, sorbed substantial amounts of iodide from solution and showed changes in sorption, due to pH and drying, similar to those shown by the soil. Freshly precipitated hydrated ferric oxide also sorbed substantial amounts of iodide from solutions of pH<5.5 but the amount decreased to zero as the pH approached 7. Sorption by freshly precipitated hydrated aluminium oxide was impossible to assess at pH<5 owing to its solubility but at pH 5.5 to 7.5 its sorption was similar to that of ferric oxide. No sorption of iodide was detected by kaolinite, montmorillonite, chalk or limestone.Drying markedly reduced the capacity for iodide sorption of the compost and soil and had a smaller effect on the ferric and aluminium oxides.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250109

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractA comparative experimental study of thawing of frozen pork legs of different weights in air, water and vacuum steam heat systems has been made with respect to thawing time, weight loss and appearance, and a mathematical model and computer programme have been developed which enable accurate prediction of thawing time for any weight of leg under any thawing condition. Very good agreement has been obtained between computed figures and experimental results.Thawing in water is faster than in air at any given temperature but vacuum thawing is not appreciably faster than water thawing. The pork legs increased in weight by 1 ± 0.3% under all conditions except high velocity air and higher vacuum thawing temperatures when losses of up to 1% were recorded. The appearance of legs thawed in air was superior to those from water and vacuum systems. Satisfactory microbiological results were obtained at a thawing temperature of 10 ºC in all system

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250110

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractA radiotracer technique, employing [35S]sulphur, has been used to determine the fate of sulphites added to hard sweet biscuit doughs. The results show that about 93% of the sulphur added to the dough as sulphite or metabisulphite remains in the biscuit. This figure is made up of about 30% sulphur as inorganic sulphate and 63% sulphur combined in an organic form; some evidence is presented to suggest that this sulphur may be combined with the biscuit protein asS‐sulphoprotein. Less than 0.2% of the sulphur remains as inorganic sulphite in the finished biscui

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250111

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY