摘要:

AbstractBoth α‐ and β‐purothionins of wheat were readily hydrolysed by chymotrypsin into peptides which were separable by ion exchange chromatography. Hydrolysis occurred rapidly at the single tyrosine residue but there was no apparent cleavage at the phenylalanine residue. Leucine residues were hydrolysed at a slower rate. Reduction and alkylation of the purothionins increased the rate at which they were hydrolysed by chymotrypsin. Seventeen peptides were isolated from α‐purothionin digests and β‐purothionin yielded 15. From amino acid analyses of the chymotryptic peptides, there were at least four differences in the primary structures of the purothionins with β‐purothionin containing 2 Asx, 1 Lys and 0.5 Leu residues which had replaced 2 Gly, 1 Arg and 0.5 Ileu residues of α‐purothionin. Tyrosine is probably the thirteenth residue from the amino terminus of both α

ISSN:0022-5142    

DOI:10.1002/jsfa.2740270302

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractPoppy seed oil (P. Somniferum) contains palmitic (12%), stearic (3%), oleic (20%) and linoleic acid (65%). Lipolysis with pancreatic lipase indicates the following glyceride composition: S3(tr), S2U (5%), SU2(34%) and U3(61%) or saturated dilinolein (19%), oleo‐dilinolein (25%), and trilinolein (27%

ISSN:0022-5142    

DOI:10.1002/jsfa.2740270303

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractAnalysis of the sterol and triterpene alcohol fractions of polyunsaturated margarine, normal butter and soft butter by gas chromatography–mass spectrometry revealed that the major components in margarines were β‐sitosterol, stigmasterol, Δ7‐stigmasterol and campesterol, while cholesterol was the major sterol in butter. The hydrogenation process used in the manufacture of margarines had no effect on the composition of the unsaponifiable components of the parent oils. Crystallisation as used in the manufacture of soft butter did not affect the quantity of cholesterol present in this

ISSN:0022-5142    

DOI:10.1002/jsfa.2740270304

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractChemical procedures, suggested by methods formerly used to prepare yeast RNA, or in the analysis of nucleic acids, were applied to the preparation of nucleic acid‐reduced baker's yeast. Water at 80–100°C extracted nucleotides but no nucleic acid from the cell, with a loss of 20% total solids and 16% total nitrogen. Water at 120°C removed part of the nucleic acid, and nearly all was extracted by 5% NaCl solution at 120°C. At room temperature, 0.5N‐HC1 removed RNA from a suspension of heatkilled yeast. NaOH at a pH of about 12.5 extracted RNA from suspensions of fresh or of heat‐killed yeast. In both cases the cells lost 25–35% solids and a similar proportion of crude protein (Kjeldahl N). The RNA‐reduced yeast preparations may require further treatment, such as extraction with organic solvents, to improve appearance o

ISSN:0022-5142    

DOI:10.1002/jsfa.2740270305

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractEight sheep fitted with both rumen and duodenal re‐entrant cannulae were used to investigate the digestion of a diet consisting of 60% molassed sugar beet pulp and 40% ground barley. Molar proportions of acetic acid in the rumen varied from 55 to 66%, of propionic acid from 15 to 26% and of butyric acid from 12 to 19%. On average, 69.1 ± 1.2% of the dietary organic matter was digested in the rumen and 89.9 ± 0.4% in the whole digestive tract. Corresponding figures for gross energy were 64.4 ± 1.4% and 87.4 ± 0.4%, for cellulose 82.8 ± 1.4% and 86.3 ± 0.8% and for α‐linked glucose polymers were 91.6 ± 0.9% and 100 ± 0%. There were only small differences in the extent of digestion of these constituents in the rumen between animals and the mean production of total short‐chain fatty acids was 55.5 ± 1.6% of the digestible energy.The mean daily amount of nitrogen entering the duodenum was 11.1 ± 5.1% greater than the dietary intake and the apparent digestibility of nitrogen was 76.7 ± 1.0%. Calculation of bacterial protein using α‐±‐diaminopimelic acid as a marker, indicated that bacterial protein constituted about 80% of the total protein entering the duodenum and that the average efficiency of rumen protein synthesis was 14.31 ± 0.75 g crude protein/100 g OM “disappearing” in the rumen. With the exception of one animal in which the rumen ammonia concentration was especially high, the efficiency of protein synthesis varied between animals over only a narrow range and there was no evidence that efficiency was influenced by variation in the pattern

ISSN:0022-5142    

DOI:10.1002/jsfa.2740270306

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractDeoiled herring silage contained an average of 17.6% dry matter (DM) and per 100 g DM: 1.86 MJ GE, 12.1 g N, 5.5 g available lysine and 3.7 g oil. The apparent digestibility coefficients for growing pigs of gross energy (GE) and nitrogen (N) for a diet containing 25% herring silage DM and 75% barley meal DM were 0.83 and 0.91, and the efficiency of retention for digested N was 0.42. The digestible energy (DE) value for the deoiled herring silage was 17.9 MJ DE/kg DM and the digestible nitrogen (DN) value was 119 g DN/kg DM.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740270307

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractA study has been made of the effect of holding temperature on the ageing of beef sternomandibularis muscle. Ageing rate increased exponentially up to 40°C, rose more slowly to a maximum at 60°C, and then decreased sharply to approach zero at 75°C. The temperature coefficient of ageing was 2.4 and was constant over the range 0–40°C. This highQ10was reflected in the high positive enthalpy of activation, (61.5 kJ). The extent of ageing was also sensitive to holding temperature; maximal extent of ageing was achieved up to ∼60°C, above this, the extent fell to a minimum at ∼65°C, despite the fact that the initial ageing rate at this temperature was still

ISSN:0022-5142    

DOI:10.1002/jsfa.2740270308

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractWhen beef sternomandibularis muscle was subjected to prolonged cooking, toughness, measured by shearing force across the grain, was reduced by about 50%. The shortened state of the muscle determined the final shear‐force value attained as in normal cooking, being considerably higher in meat at 40% shortening, than in either unshortened meat or in meat shortened by 60%. The tenderising effect of ageing was additional to that from long cooking. Ageing reduced the tensile strength of the myofibrils as measured by resistance to the shearing stresses of homogenisation. Cooking tenderising resulted from a breakdown in the collagen of the interstitial connective tissue. In cooked meat distinct linkages were shown to exist betweenZ‐lines of adjacent myofibrils. The mechanical strength of cooked meat is ascribed to the tensile strength of the fibrous components of muscle and these lateral linka

ISSN:0022-5142    

DOI:10.1002/jsfa.2740270309

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractExperiments have been carried out in which bacon rashers were fried to a final temperature of 140°C either whole or after division into lean, fat and rind. Where rashers were fried whole, similar levels ofN‐nitrosopyrrolidine were found in the lean, fat, rind and exuded fat of individual bacon sides, although there was up to a ten‐fold difference between bacon from different sides. When the lean, fat and rind were fried separately, theN‐nitrosopyrrolidine was found almost exclusively in the residual fatty tissue and the exuded fat, with only just detectable quantities being found in the lean and rind of a few s

ISSN:0022-5142    

DOI:10.1002/jsfa.2740270310

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractSamples of juice from both early and later season New Zealand grapefruit have been analysed for the presence of three enzymes that have been reported in some overseas citrus varieties. While both early and late season juice contained pectinesterase, neither polygalacturonase nor ascorbic acid oxidase was detected in juice extracted from early or late season fruit.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740270311

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY