摘要:

AbstractPerennial ryegrass (Lolium perenneL) was ensiled in laboratory silos after addition of glucose or xylose at rates of 0, 25, 35 and 45 g kg−1fresh grass. In addition, an inoculum of Lactobacillus plantarum, supplying 106organisms g−1fresh grass, was applied to all treatments. Silos were opened after 7, 21 and 100 days and the silage was subjected to chemical and microbiological analysis. AH silages were well fermented with pHs between 3·60 and 3·70 and low NH3‐N concentrations (0·80) of the glucose that disappeared could be accounted for in ethanol formation but the xylose consumed could be accounted for only if the lactic acid produced in its fermentation was metabolised further to acetic acid; indeed, for the two higher doses of xylose, the concentrations of lactic acid were reduced from the control value of 177 g kg−1DM to 140 and 120 g kg−1DM, respectively. The results indicate that the provision of extra sugar, as hexose or pentose, allows yeasts to assume a more prominent role in the fermentation with consequent wasteful fermentation of sugars. Furthermore, the suggestion is that xylose may indirectly, via a stimulation of lactate‐assimilating yeasts, encourage further metabolism o

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460202

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract‘Finger drop’, which is the dislodgement of individual banana ‘fingers’ from the bunch during ripening and marketing, was shown to be related to the conditions during fruit ripening. At high ripening temperatures fruit are generally softer than those ripened at temperatures of 20°C or lower when they reach eating ripeness. This is reflected in the strength of the fruit pedicel and can result in their having a strength sufficiently low that the fruit can easily be dislodged in handling and transport during marketing. However, ripening at very high temperatures (40°C) did not result in development of finger drop, but fruit ripened at this temperature were unmarketable. No consistent effects of ripening humidity were shown on the development of finger drop. Prolonged exposure of fruit to ethylene gas during ripening could increase finger drop in certain circumstances. Possible reasons as to how finger drop might be related to the ripening physiology of the fruit are discussed, and recommendations are made for furthe

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460203

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractBracken (Pteridium aquilinumL Kuhn) is one of the most successful weeds of the world. In the UK it covers almost 700 000 ha, and is expanding its area by 1–3 % per annum. Not only does bracken limit the usefulness of marginal land but toxic principles in the plant may cause serious illness and even death in stock animals consuming its rhizomes or fronds. Bracken‐derived acute thiamine deficiency disorders occur in pigs and horses, and acute haemorrhagic syndrome, bovine enzootic haematuria and ‘bright blindness’ are all responsible for significant losses of livestock. A great deal of research has resulted in the isolation and identification of a number of natural components of bracken, and the evaluation of their biological effects using laboratory animal models and farm livestock has been carried out in detail. One compound contributing significantly to the toxicity of bracken is the carcinogenic and mutagenic norsesquiterpene, ptaquiloside. The effects on stock and laboratory animals of bracken, its extracts or ptaquiloside are discussed in this paper; the risk to human health from consumption of bracken fronds, milk and dairy products containing bracken carcinogens or their metabolites and drinking water supplies containing bracken leachates is considered from the standpoint of the UK and beyond. Options for the control of bracken are described briefly, and the final section indicates areas of bracken research deserving of furthe

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460204

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractDripped, congealed and a mixture of dripped and congealed papaya latexes of varying charge sizes were dried in a rock‐bed solar dryer over a temperature range of 40–60°C. The time taken for the fresh latex to dry from an initial moisture content of between 73 and 80% (wet basis) to an equilibrium moisture content of between 6 and 8% varied from about 1·5 to 36 h depending upon the charge size. The latex, whether dripped or congealed, dried as pale yellow flakes which could easily be powdered and had a proteolytic activity slightly higher than that of the fresh

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460205

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractSamples of hay, silage, untreated and ammonia‐or alkali‐treated barley straw were subjected to mild and strong acid hydrolysis, and the liberated monosaccharides were analysed by gas‐liquid chromatography as theirO‐isopropylidene derivatives. From the mild acid hydrolysis, the total fructose content of the material and the amount of easily hydrolysed glucose were determined, allowing the content of non‐structural carbohydrates to be estimated. In the same operation, the content of mannitol and arabinotol in the feed samples can be determined. From the strong acid hydrolysis, the total amounts of each aldose in the forage materials were d

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460206

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe reflectance spectrum of beta‐carotene dissolved in ethanol in front of barium sulphate powder was measured with a portable fibre‐optic spectrophotometer based on a xenon flash unit and a photodiode array. Maximum absorbance (minimum reflectance) was from 470 to 490 nm. The same result was found with white adipose tissue in place of barium sulphate. Samples of subcutaneous adipose tissue from 13 cattle were measured. With a range from white to pale yellow adipose tissue, the maximum divergence of reflectance spectra was at 460 nm. With a range from pale to lemon yellow, the maximum divergence was at 410 nm. Reflectance spectra of adipose tissue had evidence of absorbance from 410 to 420 nm and at 540 and 580 nm, which might have been caused by residual oxyhaemoglo

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460207

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractChapatis and parathas were made from different combinations of durum (Triticum durumDesf) and aestivum (Triticum aestivumL) wheat to test for their organoleptic acceptability. The best accepted durum/aestivum (40:60) combination was supplemented at 10, 20, 30 and 40% levels with Bengal gram (Cicer arietinumL) flour and soya protein (Glycine maxL) concentrate. Raw and cooked samples were analysed for some amino acids and trypsin inhibitor activity. The most acceptable cooked products were fed to growing rats for estimation of protein efficiency ratio, apparent digestibility and plasma proteins. Cooking resulted in considerable losses in cystine, available lysine and trypsin inhibitor activity. The losses were greater in paratha than in chapati. Protein efficiency ratio and apparent N digestibility of chapatis were significantly higher than those of parathas. However, protein quality of soya‐supplemented parathas was better than that of chapati

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460208

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractVolatiles produced in model systems consisting of a crude enzyme preparation from Brussels sprouts (Brassica oleraceaeL varbullatasubvargemmiferaDC), sinigrin, ascorbic acid and 2‐mercaptoethanol were investigated using gas chromatography‐mass spectroscopy. 2‐Propen‐1‐yl isothiocyanate was the only breakdown product of sinigrin in the absence of 2‐mercaptoethanol but in its presence 1‐cyano‐2,3‐epithiopropane and small amounts of 2‐propen‐1‐yl cyanide also were formed. The identification of the 1‐cyano‐2,3‐epithiopropane was confirmed by comparison with a standard produced by autolysis ofCrambe abyssinicaL seed and with published mass spectra. The presence of 1‐cyano‐2,3‐epithiopropane in volatile extracts of unblanched, frozen store

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460209

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractRoasted macadamia (Macadamia integrifoliaStorey) nuts were salted at various levels up to 19 g kg−1and presented to a taste panel. The results showed that the assessors could be divided into 'salt dislikers', to whom perceived quality decreased linearly with increase in salt content, and 'salt likers', to whom perceived quality increased as the salt content increased. It follows that the nuts can be produced to suit these two market segments separately, or else a single lightly salted compromise product can be offered to both group

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460210

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPrevious studies suggest that phospholipid affects the production of volatile heterocyclic compounds during cooking by participating in the Maiilard reaction, and also plays an important role in the formation of the characteristic aroma of cooked meat. These effects can be mimicked using aqueous model systems. The identities of 109 volatile products of model Maillard reactions involving glycine and ribose, with and without phospholipid, have been investigated using gas chromatography‐mass spectrometry and the individual odours of these systems noted during sensory assessment of the effluent from the gas chromatograph. The incorporation of phospholipid increased the overall number of volatile compounds and variety of odours produced, as well as altering the nature of the dominant components and aroma

ISSN:0022-5142    

DOI:10.1002/jsfa.2740460211

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY