摘要:

AbstractBulk samples of perennial ryegrass and white clover were deep frozen immediately after harvesting. Within 2 days one portion was freeze‐dried, one was oven dried at 108 ºC, and the remainder was stored intact at −16 ºC. The two dried samples, after grinding, were stored either in air at ambient temperature, or under nitrogen at −16 ºC. Portions of the deep‐frozen, intact sample were withdrawn after storage for 2, 4 1/2 and 9 months, freeze dried and ground, immediately prior to analysis. Determinations of the total higher fatty acids (HFA) by titration and individual higher fatty acids by gas‐liquid chromatography, were made on all samples after storage for the above periods.HFA in the dried and ground ryegrass or clover fluctuated throughout the experimental period under all conditions of storage. The greatest deterioration was exhibited by freeze‐dried, air‐stored ryegrass which lost linolenic acid at a rate of 0.55 mmol 100 g−1month−1. Negligible changes in total nitrogen occurred in all dried samples after 9 months storage. Non‐protein nitrogen extracted from clover, however, was significantly higher after oven‐drying as compared with freeze‐drying.The most satisfactory mode of storage was to store the intact, undried herbage at −16 ºC and then freeze dry and grind immediately before analysis. Under these conditions, HFA

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250602

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe α‐ and β‐purothionins, which differ slightly in amino acid composition and have slightly different mobilities in gel electrophoresis, were not different in other physical properties. Molecular weights determined by sedimentation equilibrium were 5100 and 5300, respectively, by osmotic pressure, 6100, and by gel permeation chromatography, about 7500. Circular dichroism (c.d.) spectra were compatible with about 40% α‐helical structure for the purothionins. An unusually strong negative band near 268 nm was found in the near‐u.v. region of the c.d. spectrum. The optical activity in this region may be attributed primarily to the high disulphide content of the molecule, since the purothionins contain no tryptophan and only a single tyrosine residue which appears to contribute some fine structure in the 270 to 290 nm region of the c.d. spectrum. The u.v.‐fluorescence spectrum was characteristic of tyrosine, but the low quantum yield was indicative of quenching by disulphide or other groups in the protein. An intrinsic viscosity of 2.7 cc/g suggests a compactly folded, globular structure for the purothionins. Mobilities of 11 × 10−5cm2V−1s−1at pH 3.1 and 7.2 × 10−5cm2V−1s−1at pH 8.6 were obtained from fre

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250603

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractDry matter contents of 41 high moisture roughage samples and 31 samples of faeces were determined by toluene distillation, freeze drying, microwave drying and oven drying at 70 and 100 ºC. Significant differences were recorded between the results on roughages, with a toluene distillation method giving the most accurate results. The dry matter values of faeces were not significantly different for faeces from low intake levels. Further work is needed to resolve the influence of intake level on dry matter losses incurred during the drying of faeces

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250604

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractA detergent extraction technique was applied to quantitatively separate the outer layers of the wheat grain from the starchy endosperm. These layers were examined under the light microscope which showed that the cellular structures were intact and the contents of the aleurone cells had not been extracted. Milling studies demonstrated that the extraction technique allowed an accurate estimate to be made of the flour‐yielding potential of a wheat provided that the milling system was capable of fully realising this flour‐yielding capacity. The small‐scale nature of the test allows it to be applied in wheat breeding programmes at an early stage as a predictive test for flour

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250605

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractA rapid method is described for the determination of potassium in mixtures containing potassium salts and basic slag. Four Geiger Muller tubes connected in parallel are used to measure the natural radioactivity of40K and the potassium contents of the mixtures are evaluated from a previous calibration. The effects of variation of particle size of both the potassium source and the basic slag are demonstrated, the count rate varying in different directions as the fineness increases in the two cases.Use of the technique in the production of a mixture of potassium chloride and basic slag has shown that the results from the method are comparable with those of the flame photometer.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250606

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractExtracts of the steam volatiles of cooked potatoes and of a dehydrated, granular potato product have been prepared. High‐boiling fatty acids preponderated and were removed prior to concentration and examination of the resulting essences by combined gas chromatography‐mass spectrometry‐odour assessment. Thirty‐five components were identified in potato essences and 20 in a potato granule essence. Chemical and retention data indicated that 2‐methoxy‐3‐ethylpyrazineFor clarity in this paper, the methoxy substituent is assigned the 2‐position in pyrazines, and is written first, irrespective of the rules of nomenclature.was present in potato volatiles and mass spectral evidence was obtained of its presence in potato sprout essence. Synthetic work confirmed the known characteristic raw potato odour of 2‐methoxy‐3‐ethylpyrazine and demonstrated that isomers do not possess it. Lack of volatiles rather than off‐flavour is believed to account for the differences between the flavour of cooked potatoes and of the

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250607

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractA surface‐active principle of the nature of a globulin and an arabogalactan type polysaccharide have been shown to occur in the black gram. The polysaccharide does not exhibit surface activity, but confers thermal stability on the foam formed by the protein and prevents its disruption by heat. Together, these two components appear to be responsible for the characteristic soft, spongy texture of leavened foods containing the legum

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250608

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractA procedure for direct gas chromatographic analysis of volatile constituents present in the headspace above wines has been developed. Samples of wine (100 ml) and its headspace were conditioned for specified times and temperatures so as to reach air‐liquid equilibrium in a special large syringe (2000 ml) designed in our laboratory. The headspace volatiles were collected directly, freed from water and ethanol in a short trap packed with Porapak Q connected to the syringe. The vapour passed from the syringe to the precolumn through a container holding the internal standard under strictly defined conditions of temperature, pressure and flow rate. The elution of volatiles from the traps was accomplished directly into the oven of the gas chromatograph. The operating parameters of the system are discussed. This procedure allows the qualitative (and quantitative) determination of different volatile compounds present in the headspace above wines. The factors which influence the air‐liquid partition of volatile compounds present in wine are also exami

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250609

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe fatty acid compositions of extracted and commercial samples of cottonseed oil, groundnut oil, sesame oil and butter fat were determined by gas‐liquid chromatography. These fats were subjected to frying temperature (195 ºC) for 3 hours and the peroxide value, iodine value, free fatty acid content and the carbonyl value were determined at hourly intervals. The stability of the oils did not correlate well with the ratio of C18:2 to C81:1 nor with the degree of unsaturation. Also, it was not a function of the susceptibility of these oils and fat to hydrolyse during the heating process. The data suggest that the fatty acids, present in these oils and fat, influence each other's oxidation and thus affecting the rate of oxidation. It appears that one of the major predisposing factors in the degradation of these oils and fat is the amount of saturated fatty acids which are present in contact with unsaturated and peroxidised fatty acids. This explanation has been discussed in relation to the degree of unsaturation of the oils used in the experiments and their vitamin E conten

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250610

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractParboiling decreased the thiamin content of rice. Nevertheless, milled parboiled rice contained more thiamin than milled raw rice at the same degree of milling because parboiling caused thiamin to diffuse inwardly. Both the degree of loss and the degree of diffusion depended on the severity of the heat treatment. Bran‐polish of parboiled rice had a higher fat and protein content than bran‐polish of raw rice at the same degree of milling because the starchy endosperm of parboiled rice had a greater resistance to milling and so the bran and the germ were more effectively removed. Milled parboiled rice tended to have lower protein content than milled raw rice. Starch content was lower in bran‐polish from parboiled

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250611

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY