摘要:

AbstractThree accessions of winged bean [Psophocarpus tetragonolobus(L.) DC] tuberous roots from Thailand were examined for their crude protein (N × 6.25), non‐protein nitrogen and starch contents. The roots were further analysed for their trypsin inhibitor and urease activities and for the presence of tannins and cyanogenic compounds. Crude protein was found to be high in comparison with other root crops (5.7–6.7% fresh weight) and this contained a high proportion of non‐protein nitrogen (7.4–15.0%). Amino acid content of the crude protein, when compared with mature winged bean seeds, revealed a deficiency in the sulphur‐containing amino acids but an exceptionally high aspartic acid content. Starch was the major carbohydrate present in the flesh of the roots (21.7–32.1% fresh weight). Root samples were found to contain high levels of trypsin inhibitory activity (13.5–30.1 TIU mg−1fresh weight). No urease activity or cyanide could be detected in any of the root ac

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330202

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractIncreases in the total grain nitrogen of barley (cv. Julia and Bomi), resulting from increased N fertilisation, are accompanied by decreases in the relative lysine content of the grain proteins. Extraction of the grain proteins shows that the high‐N grain have increased relative and total amounts of the lysine‐poor storage protein (hordein) fraction. There are only small increases in the total amounts of the other more lysine‐rich protein fractions (salt‐soluble proteins and glutelin+residue proteins). There is also little or no effect on the amino acid compositions of the fractions. Consequently, it is concluded that the decreased relative lysine content of the whole grain is due to the increased synthesis of hordein. Further evidence for this hypothesis comes from similar studies with the high‐lysine mutant, Risø 1508, in which the high‐lysine character results from a decrease in the relative and total amount of hordein. The hordein fraction does not increase disproportionately with increasing grain N, nor does the relative lysine content of the grain decrease. There is no effect of grain N on the polypeptide compositions of the salt‐soluble proteins of either line. However, in Bomi and Julia increased grain N does result in an increase in the relative amount of sulphur‐poor ‘C’ hordein polypeptides in the hordein fraction. It is speculated that this results from limitatio

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330203

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractSeveral gels used for gel filtration were compared for their effectiveness in separating protein from lucerne (alfalfa) extracts. Separations of protein and non‐protein components on Sephadex G‐50 and Bio‐Gel P‐10 were good at loading levels up to 35% of column volume. This separation was maintained upon concentrating the extract in an ultrafilter. The lyophilised protein concentrates were cream coloured, were very soluble, and had a good balance of amin

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330204

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractSpecific weight, 1000 grain weight, and percentages of grain held by a 2.5 mm sieve and passing through a 2.2 mm sieve were measured in husbandry trials carried out on spring barley at Craibstone, Aberdeen, from 1975 to 1979. Sowing date had the greatest influence on these properties, apparently due more to poor crop development than to increased foliar disease following late sowing. Fungicide treatment, particularly a spray application of tridemorph, resulted in an improvement, but growth regulators, especially when applied late or at high rates, had the reverse effect and both chemicals affected specific weight less than other parameters. The mean specific weight, 1000 grain weight and grain size of a number of varieties declined at nitrogen application rates above 50 kg ha−1, but there were significant differences between varieties, with short‐strawed, small‐grained varieties such as Midas and Maris Mink being most affected. Different levels and application methods of phosphatic fertiliser had little effect on the parameters mea

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330205

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330206

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe digestibility of the carbohydrate components and the metabolisable energy (ME) values of two yeasts grown on hydrocarbon (BPG and BPL yeasts) and a filamentous fungus grown on carbohydrate waste (RHM fungus) have been investigated in rats and chicks. The microbial products were included at three different levels. Mannan, and chicks, and glycogen have been shown to be the major constituent polysaccharides of these microbial products. Glycogen in the three samples tested was found to be completely digested by both animals. Mannan, β‐glucan and chitin were less digestible and their utilisation varied according to the level of inclusion in the diet. The difference in the ability of the animals to digest the cell wall carbohydrates or to metabolise the gross energy from the test ingredients was significant (P0.001). Rats digested up to 68.1 % chitin, 47.4% β‐glucan and 41.8% mannan but the highest value obtained for chicks was 12.9% for mannan. Chitin had the lowest digestibility in chicks varying between 0.7 and 2.9%, whilst values for β‐glucan were between 3.3 and 11.7%. Uncorrected ME values for BPG yeast, BPL yeast and RHM fungus, respectively, were 13 617, 13 190 and 12 194 kJ kg−1dry matter for chicks and 16 380, 15 903 and 14 107 kJ kg−1DM for rats. Correction of these values to zero nitrogen retention lowered the values by about 18% in chicks and 8 % in rats. Adjusting the values to 30 and 50% nitrogen retention for rats and chicks, respectively, resulted in values which were very close to uncorr

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330207

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractSystematic studies of factors that inactivate soya bean trypsin inhibitors showed that thiols facilitate heat inactivation, as illustrated by the following examples. Heating soya flour in an aqueous medium in a water‐bath from 25 to 93°C for 1 h showed that heat alone does not begin to inactivate the inhibitor until about 55°C (around 10% inactivation). The corresponding value at 85 °C is 60%. In contrast, inactivation in the presence ofN‐acetylcysteine proceeds more rapidly, as shown by 70% inactivation at 55 °C and 94% at 85 °C. These results, and additional data, illustrate the complementary co‐operative effect of heat and thiols in inactivating soya bean trypsin inhibitors in commercial soya flour. The thiol treatment also strikingly enhances the in‐vitro digestibility of soya proteins by trypsin. The results are discussed with reference to the role of disulphide bonds in the mechanism of enzym

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330208

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe extractability of nitrogenous material from the seeds of 12 winged bean accessions has been investigated. Little variation in nitrogen content and extractability in water or salt solution was obtained, although decortication considerably reduced the levels of extraction. The effect of three oil extraction procedures on the extractability of nitrogenous material at different pH values is reported. Protein isolates were prepared and simple laboratory tests were used to evaluate their functional properties. The prepared winged bean isolates possessed very low bulk densities and high fat absorption values and the relationship between these factors was investigated further. Winged bean isolates showed high (100%) nitrogen dispersibilities and were able to form heat‐stable emulsions. They did not form gels under the conditions used except in the presence of CaCl2. Isolates prepared from unheated winged bean flour formed stiff but unstable foams. The relationship between the oil extraction procedure and isolate yield, purity and functional properties is discusse

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330209

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractA method to measure dietary fibre in oranges has been developed. Pectin was extracted from the food sample using heat, acid and a cation‐exchange resin. This was followed by enzymic digestions, using pepsin and pancreatin, of the remaining residue. Optimal levels of resin, pH, time and temperature for maximum pectin extraction were found. Optimal levels of enzymes and pH for maximal enzyme digestion was also found. Other food products tested for dietary fibre content were: cauliflower, oranges, pole beans, carrots and whole wheat flour. Values found were greater than those for other fibre analyses; however, most other methods fail to measure the water‐soluble indigestible components, such as pec

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330210

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe advantages of a commercial constant‐stress viscometer (the Deer Rheometer) for monitoring the kinetics of starch degradation are presented. The concentric cylinder arrangement is particularly appropriate for studying non‐Newtonian dispersions at the early stages of degradation. The rates of dissolution of wheat and ‘soluble’ starches in dimethylsulphoxide at 25°C are clearly distinguished, and the sensitivity of the extent of dissolution to the degree of agitation is demonstrated. The instrument provides a precise and convenient technique for following the hydrolysis of ‘soluble’ starch by α‐amylase. The reliability is confirmed by observing that the viscometrically determined optimum enzymic activity agrees with that found by c

ISSN:0022-5142    

DOI:10.1002/jsfa.2740330211

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY