摘要:

AbstractFour mature Suffolk × half bred wether sheep, fitted with rumen fistula and re‐entrant cannulae at the proximal duodenum and terminal ileum were given in sequence, a control diet (diet 1) and that diet supplemented with either 20 or 40 g saliva salt kg−1(diets 2 and 3 respectively). The addition of 20 g salt kg−1failed to alter significantly the rumen fermentation pattern and dilution rate. In contrast, the feeding of diet 3 resulted in a significant increase in the molar proportions of ruminal acetate, a non‐significant decrease in propionate and a significantly higher rumen dilution rate (D), which was positively correlated with the molar proportions of acetate. Ruminal NH3‐N concentration tended to increase with salt supplementation, with the greatest concentration being observed at the highest level of salt inclusion. The presence of the salts significantly reduced the degradability of the feed protein within the reticulorumen. The dietary inclusion of the salts resulted in a non‐significant increase in total amino acid N (TAA‐N) and a significant increase in the organic matter entering the s

ISSN:0022-5142    

DOI:10.1002/jsfa.2740331102

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractExperiments by Rothamsted staff over 20 years show that N (protein) concentration in wheat grain is influenced considerably by several husbandry treatments other than total fertiliser N. Even small differences can be of practical importance if values lie close to the minimum standard for bread wheat. In 15 experiments which tested timing of fertiliser N, an extra 60 kg ha−1would have been needed in autumn to increase grain‐N concentration by 0.1% on average, but only 43 kg in early and 30 kg in late spring. The response to autumn N was similar in a ley‐arable rotation experiment Fertiliser N applied to a previous potato crop gave a grain‐N% increase equivalent to a quarter of the fresh application on a silty clay loam soil but none on a sandy loam. Cumulative annual dressings of farmyard manure benefited grain‐N% as did residues from FYM applied to a previous potato crop, which gave increases equivalent to those from 16 kg ha−1of fresh fertiliser N. In ley‐arable rotation experiments, wheat after arable cropping did not reach bread‐quality standard with the largest amount of fertiliser N (150 kg ha−1), but after lucerne N% values exceeded the threshold value of 2.14% N with all rates. Benefits from lucerne and a grass‐clover ley were still considerable when wheat was grown as a second test crop after potatoes. Yield responses to these husbandry treatments tended to be small and positive, except that in the presence of larger dosager of fertiliser N farmyard manure sometimes

ISSN:0022-5142    

DOI:10.1002/jsfa.2740331103

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractDetermination of the protein contents of 14 varieties of Italian millet revealed considerable varietal differences. The total protein of the 14 varieties was fractionated into albumin‐globulin, prolamin and glutelin fractions. The prolamin fraction constitutes the major storage protein of the grain. There is a positive correlation between protein content and the prolamin levels of the seeds and the increase in protein content is largely due to an increase in the prolamin content. The amino acid composition of each of 14 varieties of the millet and the individual protein fractions from three varieties were determined. The limiting amino acids are lysine followed by tryptophan and the sulphur containing amino acids, methionine and cystine. The lysine content of the grain decreases with increase in protein content. The total protein has a rather high content of leucine. SDS‐polyacrylamide gel electrophoresis of the protein fractions indicated similarities in the prolamin fraction and differences in the albumin‐globulin and glutelin fractions of the different vari

ISSN:0022-5142    

DOI:10.1002/jsfa.2740331104

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractA trypsin/α‐amylase inhibitor (TAI) and a chymotrypsin/trypsin inhibitor (CTI) were isolated in homogeneous forms from ragi grains by affinity chromatography using immobilised chymotrypsin and immobilised trypsin. Both the inhibitors were capable of inhibiting the caseinolytic and amidolytic activities of bovine trypsin whereas the esterolytic activity of the enzyme was only weakly affected. While TAI had no action on chymotrypsin, the CTI exerted an inhibitory effect on the caseinolytic activities of bovine α‐, β‐, γ‐ and ş‐chymotrypsins. Both the inhibitors could inactivate the proteolytic actions of bovine as well as human crude pancreatic preparations, TAI showed inhibitory activity against human pancreatic, porcine pancreatic and human salivary amylase in the ratio of 6.5:5:1. The possible practical application of TAI for the purification of α‐amylases by affinity chromatography is indicated based on the demonstration of the dissociation of porcine pancreatic amylase from a ‘trypsin‐TAI‐amylase’ trimer complex in the presence of maltose. The antichymotryptic activity of CTI was less stable than its antitryptic activity at high temperature, acidic pH and on treatment with pepsin. Modification of arginine residues by 1,2‐cyclohexane dione led to a preferential inactivation of its antitryptic activity. Treatment of CTI with trinitrobenzene sulphonic acid or pronase, however, caused almost identical loss of both antitryptic and antichymotryptic activities. The mode of inhibition of CTI was non‐competitive for trypsin but was uncompetitive for chymotrypsin. The CTI could bind to immobilised trypsin or chymotrypsin but not to immobilised TPCK‐c

ISSN:0022-5142    

DOI:10.1002/jsfa.2740331105

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe precipitate (thermal aggregates) formed in the presence of sulphydryl compounds>0.01M[β‐mercaptoethanol (ME), gutathione (reduced form) (GSH), and cysteine (oxidised form) (Cys)] consisted of a basic monomer subunit and oligomerised sub units but did not contain polymerised subunits. The content of the basic subunits in the precipitate increased with increasing concentrations of sulphydryl compounds, and on addition of 0.5MME reached a level of 90% or more of the precipitate. The time course of the formation of the basic monomer subunit and oligomerised subunits showed that basic monomer subunits tended to be precipitated at the initial stages of heating. This was followed by the formation of oligomerised subunits. Heating an 11S globulin solution containing sulphydryl compounds accelerated the precipitation reaction. However, this did not produce a high degree of polymerisation due to sulphydryl‐disulphide interchange. A scanning electronmicroscope image of thermal aggregation induced in the absence of any sulphydryl compounds showed, however, that polymerisation has a major role in the formation of a network structure. The mechanism of oligomer and polymer formation is discussed

ISSN:0022-5142    

DOI:10.1002/jsfa.2740331106

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractCharacteristic post‐mortem changes in subcellular structures are described which are caused by the penetration of acetic acid during incubation of cocoa seeds in aqueous media. In the storage cells lipid is agglomerated and separates from hydrophilic portions in proportion to the acetic acid concentration and pH. This effect is less pronounced at 50°C than at 40°C. In the absence of acetic acid or with very low concentration of undissociated acetic acid other substructural characteristics dominate in most of the cells. At 50°C Post‐mortem changes do not induce lipid agglomeration. At 40°C the intact protein vacuole swells and its matrix structure becomes spongy as a response to in‐vivo water absorption. Finally, it is shown that a concentration gradient persists in whole seeds for most of the time required for fermentation, because of the slow diffusion of acetic acid. The results are compared with temperature effects on subcellular structures and are discussed in relation to their significance for proteolysis in cocoa seeds during fer

ISSN:0022-5142    

DOI:10.1002/jsfa.2740331107

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractDuring anaerobic incubation in citric acid/NaOH (35 mmol; pH 5.5) at 40°C the fresh weight of ripe cocoa seeds (without testae) increases considerably (17–27% within 40 h) by water absorption. This is similar to water uptake during germination at 25–30°C. At 50°C in the same medium, weight increase (3.5–7.3% within 40 h) as well as net water uptake is low. Subcellular compartmentation is destroyed at 50 but not at 40°C. Since water uptake is greatly reduced or is impaired at 40°C in the presence of osmotically active substances like sucrose, it is concluded that intact vacuoles in the cotyledons are responsible for high water absorption. In the presence of acetic acid (200 mmol; 50°C) weight increase is low but loss of dry matter is increased by exudation. These findings are discussed with respect to protein vacuole swelling and proteolysis during fermentation and

ISSN:0022-5142    

DOI:10.1002/jsfa.2740331108

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractWith the aid of a 1.5% sodium dodecyl sulphate solution (SDS) the proteins of two Dutch wheat flours were separated into an SDS‐soluble and an SDS‐insoluble fraction. The SDS‐soluble fraction was fractionated with the aid of ethanol precipitation and gel filtration chromatography into albumins, globulins, gliadins, glutenins II and III, and glutelins I, II, III and IV. The SDS‐insoluble proteinaceous material was separated into glutenins I and glycoproteins. The protein fractions were identified with the aid of SDS‐polyacrylamide gel electrophoresis and amino acid analysis. The glutenins I and II consist of A, B and C subunits. Their molecular weights ranged from about 600 000 to 10 million. The glutenins III consist only of B and C subunits and their molecular weights ranged from 300 000 to 600 000. A hypothesis explains how the glutenins III are the precursors for glutenins I and II and how they contribute to gluten's structure. The glutelins I consist of α β and γ subunits and their molecular weights ranged from about 600 000 to several millions. The glutelins II consist also of α β and γ subunits with a molecular weight of about 300 000 to 600 000, while the molecular weights of the glutelins III and IV ranged from 10 000 to 200 000. All glutelins are insoluble in 70 % aqueous ethanol and 5Murea, but soluble in SDS and 0.1MNaOH. Only the glutelins III and IV are soluble in 0.1MHAc. The globulins consist of a heterogeneous fraction of components, their molecular weights arranged from 98 000 to 10 000. The gliadins form a heterogeneous but homologous group of polypeptides with an average molecular weight of 35 000. The albumins consist of components with molecular weights lo

ISSN:0022-5142    

DOI:10.1002/jsfa.2740331109

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractActomyosin was purified from post‐rigor fish stored for various times on ice and was characterised by Mg2+‐ATPase activity, ATP‐sensitivity and SDS‐polyacrylamide gel electrophoretic patterns. It had a similar reduced viscosity to that of the myofibrillar extract and the viscosity of both extracts fell in a similar manner as the time of storage of the whole fish on ice increased. No changes in the extractability, the Mg2+‐ATPase activity or the electrophoretic pattern of actomyosin were detected when extracted from fish muscle held for up to 11 da

ISSN:0022-5142    

DOI:10.1002/jsfa.2740331110

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractChanges were observed in the fluorescence of skeletal muscle of many species of fish during storage in the frozen state. As intrinsic pyridine nucleotide fluorescence associated with degree of freshness, faded, two other visible fluorochromes developed. Production of the latter was favoured by minimal pre‐freezing delays, protection from air, low pH and high cold‐store temperatures. The results suggest that careful visual examination of fish muscle fluorescence, before and after thawing, could be useful in the assessment of cold storage hist

ISSN:0022-5142    

DOI:10.1002/jsfa.2740331111

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY