摘要:

AbstractA gas chromatographic method has been developed for the analysis of saponins in quinoa (Chenopodium quinoaWilld). The method, which involves separation and quantitation of the trimethylsilylated sapogenols, has been applied to the analysis of the UK‐grown crop obtained by selection from lowland Chilean ecotypes. Total saponin contents of 1·03 and 1·19% were found for material grown in 1987 and 1988. The major aglycone in the quinoa saponin mixture was identified as phytolaccagenic acid (>40% total), with hederagenin (∼25%) and oleanolic acid (30%) aglycones also being present. The effects of washing and abrasion on total and individual saponin content were investigated; the data obtained suggest differential cellular locations of the individual saponins. The processing of quinoa led to changes in sensory characteristics; removal of saponins was associated with reductions in bitterness and astringency. Microscopic analysis revealed considerable differences in washed and abraded samples, both before and after cooking; in particular the abraded samples showed a greater degree of cellular disru

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540202

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe efficacy of a commercial inoculant, Natuferm, which contains multiple strains of lactic acid bacteria, was examined in seven experiments using 6 m3pilot‐scale silos. Samples taken during the fermentation period were analysed and compared with samples from untreated controls and formic acid silages. Good quality silages were obtained with crops of low dry matter content (12–14%) and with a water soluble carbohydrate content of 1·5% related to fresh weight. The addition of Natuferm resulted in increased lactic acid levels (50–90%) during the initial fermentation, and pH dropped faster compared with the untreated controls. Compared with the formic acid silages the level of enterobacteria declined rapidly in both the inoculated and untreated silages. In two of the experiments a pronounced difference in enterobacterial count was observed between the Natuferm and control silages on day 2. The effluent volumes were recorded, and the pH and the dry matter content of the effluent were determined. Compared with the formic acid silages, a 40% average reduction of the effluent flow was observed from Natuferm silages, and in most experiments there was also a reduced effluent volume compared with the controls. Analyses of 174 Natuferm silages and 73 formic acid silages from full scale (farm) silos revealed no significant differences in silage quality between the two additives. Natuferm silages with a dry matter content below 20% were not significantly different from silages with a dry matter content abo

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540203

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractNear infrared reflectance (NIR) spectroscopy is a rapid, cheap, simple technique which can be used to make quantitative analyses of the concentrations of nutrients in plant tissue. The application of NIR to determine nitrogen in rice was examined. The absorbance spectrum of rice (Oryza sativaL) shoot tissue was similar to that of the temperate cereal wheat even though rice tissue has a much higher silica content.A 19‐filter NIR instrument was calibrated to estimate the nitrogen content of rice shoots with between 0·8 and 3·50% N by the Kjeldahl technique. The calibration model developed used three wavelengths to account for 96% of the variation in sample Kjeldahl nitrogen concentration. This model was validated using 67 samples comprising five rice varieties grown on farms in two seasons in southern New South Wales. The standard error of prediction of the model was 0·15% N. A tissue testing service using this NIR calibration is now operational for rice crops in southern New South W

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540204

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractSamples of internodes and leaf blades from normal and bm3 maize (Zea maysL) harvested at dough to glazing stage were studied separately to determine their dry matter content, wall composition (NDF, ADF and ADL) and digestibilityin sacco. For examination by light and scanning electron microscope, fragments 0·5 cm long were cut halfway along the internode beneath the female ear and on the corresponding blade. The wall and lignin contents of the bm3 maize were lower than in normal maize. The bm3 maize had a greater extent and faster rate of internode and blade disappearance in the rumen than normal maize samples. The histological structure of the two maizes was the same, but after 24 h in the rumen the parenchyma of the bm3 maize had degraded faster and the secondary walls of the fibres of its vascular bundles were degraded whereas those of normal maize had remained intact. After 72 h in the rumen the sclerenchyma of normal maize had changed little whereas that of the bm3 maize had much thinner walls and was abundantly colonised by rumen bacteria

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540205

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractTaste testings and saponin estimation by a simple afrosimetric method showed that quinoa containing 0·11% saponins or less (corresponding to foam heights of 1·0 cm or less) can be considered sweet. A variation of the standard afrosimetric method is described which reduces total analysis time from 73 to 7 min. Used with the proper precautions, this rapid method, in which quinoa producing foam heights of 1·3 cm or less is considered sweet, is suitable for selecting promising low‐saponin varieties in field trials and for monitoring the efficacy of abrasive dehulling (polishing) as a debittering pro

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540206

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractAflatoxin contamination in two varieties of mustard (Brassica junceaL), Varuna and BR‐40, sown on three planting dates (1, 15 and 30 November) under two different cropping patterns, viz monocropping and mixed cropping (along with the UP‐262 variety of wheat), was examined in rabi (winter) crops of 1987–1988 and 1988–1989. Analysis of variance showed a significant effect of planting date and cropping pattern as well as a combined effect of planting date × cropping pattern. Delayed planting (30 November) resulted in a very high level of aflatoxin contamination. The level of aflatoxin was low when mustard was cultivated along with wheat (mixed cropping). Varuna was more susceptible to aflatoxin than BR‐40. The maximum number of fungi was recorded in mixed croppi

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540207

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractEnzymic browning in apricots (Prunus armeniacaL) was found to be catalysed by a catechol oxidase (o‐diphenol oxidase) and a laccase (p‐diphenol oxidase), both acting on catechin and chlorogenic acid as the natural substrates. The laccase was identified as such by substrate specificity tests and the effects of selective inhibitors. The enzymes were tightly bound to the fruit tissue and were inactivated by holding at 80°C for 10 min. The levels of phenolic compounds in healthy and rotted apricot tissue were compared by paper chromatography; the levels of catechin and chlorogenic acid were reduced in the rotted ti

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540208

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractMaize (Zea maysL) germplasm is needed with resistance to infection byAspergillus flavusand/or subsequent contamination by aflatoxin B1(AFB1). A select group of maize populations were evaluated for their resistance to AFB1contamination at three locations. Four populations (Ibadan B and three others derived from crosses between Corn Belt inbreds and diploid perennial teosinte.Zea diploperennis) were compared with a susceptible hybrid check in a randomised complete block experiment with 10 replicates in Georgia, Missouri and South Carolina for two years. Ears were not inoculated, and naturally occurring concentrations of AFB1in harvested grain were analysed for population differences. Ibadan B and Mo2 W ×Z diploperennishad significantly lower average amounts of AFB1, 19 μg kg−1and 18 μg kg−1, respectively, than other test entries. Backcrossing to susceptible Corn Belt inbreds produced populations as susceptible as the check when resistance was measured as the concentrations of AFB1in the grain. The consistency and significance of low AFB1concentrations for Ibadan B and Mo20W ×Z diploperennissuggest that these may be useful sources of res

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540209

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe effect of temperature, salt concentration and dielectric constant of the medium on the liquid/liquid equilibrium in broad bean vicilin/sodium chloride/water and pea vicilin/sodium chloride/water systems was investigated, and the upper critical points were obtained. The critical protein concentration and critical exponents for vicilin‐containing systems are compared with those for legumin‐containing systems. Phase separation in the vicilin solutions was observed at a lower salt concentration than phase separation in the legumin soluti

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540210

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe effects of attaching a hydrophobic amino acid residue, valine, to the ϵ‐amino groups (lysine residues) of bovine serum albumin (BSA) on the physicochemical and functional properties were assessed. The valyl groups were attached using an N‐carboxyvaline anhydride derivative. The valine content of BSA was increased from 27 mol mol−1protein to 47·91 or 53·72 mol mol−1. The number of lysine residues acylated was dependent on the pH of the reaction mixture as was the degree of polyvalylation. Attachment of polyvalyl chains resulted in improved whipping and gelling properties compared with a control sample of ultrafiltered BSA, and interfered with the formation of α‐helices. Hydrophobicity measurements using the fluorescent probecis‐parinaric acid revealed increased hydrophobicity values only after the modified samples had been

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540211

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY