摘要:

AbstractIn this review the major nitrogenous components of herbage have been identified and the effects of both plant and microbial enzyme activity on these components during the ensilage process have been described. In particular, the specific effects of the lactic acid bacteria and clostridia on amino acid degradation and the end products of such microbial activity are summarised. The effect of formaldehyde in preventing proteolysis is also discussed.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290602

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractFree and protein amino acid contents of whole‐plant maize ensiled with or without urea were determined at intervals during the fermentation process. The free amino acid content of both untreated and urea‐treated silage increased with time in storage, but the increases were generally larger in the treated silage. The true protein of untreated silage decreased with time in storage. In urea‐treated silage many individual amino acids increased considerably. Among those were the essential amino acids isoleucine, lysine, threonine and valine. The result was a net gain of several amino acids in the treated silage while there was a general decline of most amino acids in the untreated silage. Urea‐treated silage at day 20 contained 38% more true protein and 150% more free amino acids than did untreated silage. The implications of these changes for dairy cattle nutrition are di

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290603

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractIn‐vitro experiments have indicated that the soluble lignin‐carbohydrate complex (LCC) produced in the bovine rumen is not significantly affected by further digestion in the rumen after passing into solution. The LCC has been shown to precipitate at the low pH of the abomasum and is present in the solid fraction of the faeces. It is concluded that digestion of the LCC is not likely to be significant after it passes from the ru

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290604

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe rate of release of N, S, P, Ca, Mg, K and Na from four milled tropical hays in nylon bags in the rumen of cattle over a 168 h period were measured. The hays were:Medicago sativa, Stylosanthes humilis, Chloris barbataandHeteropogon contortus. Three ways were used to express results: (a)element as % of element initially present; (b) element as % of dry matter initially present, and (c) element as its concentration in residual dry matter. The proportions of elements removed during digestion were positively related to initial concentration of the elements in the hays, with the exception of P inC. barbatahay. High proportions of Mg and K were released within 48 h in all hays. Only about 60% of N, P and Ca initially present was removed even after 168 h in the rumen. Amounts of elements remaining became constant for each element after 48 h and were for N, 6.0; Ca, 3.0; K, 1.0; P, 0.7; Na, 0.7; S, 0.5 and Mg, 0.3 g element kg−1DM initially present. Concentrations of elements in the residual dry matter after decreasing in the first 24 h, increased in the latter stages of digestion, even though cell wall digestion continued. The four hays released the seven elements differently. Generally, the elements inMedicagowere most soluble and those inHeteropogonthe least. However, the extent of solubilisation inStylosanthesand inChlorisvaried with the element concerned. InHeteropogonhay, which had low element concentrations initially, less than half of the N, S, P, Ca and Na were released even after 168 h digestio

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290605

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractSpirit derived from heap‐fermented grape marc was found to owe its undesirable odour to a series of unsaturated carbonyl compounds present in trace amounts. The principal odoriferous aldehydes in the spirit includedtrans‐2‐octenal,trans,trans‐2,4‐heptadienal,trans‐2‐nonenal,trans,trans‐2,4‐nonadienal,trans‐2‐undecenal andtrans,trans‐2,4‐decadienal. The same compounds were found in a sample of autoxidised grape‐seed oil. This implied that oxidation of the polyunsaturated fatty acids in the grape‐seed oil was responsible for off‐odours of the marc spirit. The odorous carbonyl compounds could be removed by passing the marc spirit through a strong anion‐exchange resin in the bisulphite form. By analysing total acetaldehyde concentration in the treated spirit and relating this to the sensory characteristics of the spirit, an indirect analytical monitor of the efficiency of the deod

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290606

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe firmness of fruit of tomato cultivars Sonato, Grenadier, Adagio, Extase and Exquise obtained from growers was significantly different at time of harvest and after storage for 7 and 14 days at 19‐23°C. However, all fruit had firmness values above 1000gforce on day 7 and above 700gforce on day 14, which are postulated minima for sale of fruit at retail level and use in the home respectively. There is no evidence to downgrade fruit of Sonato from a firmness point of view. Variation in fruit firmness within a sample was considerable for most cultivars on each testing date, and coefficients of variation were calculated to quantify this. Correlation coefficients between Hunter a/b ratio and firmness for the different cultivars ranged from ‐0.91 to ‐0.97. Regression lines relating a/b ratios to firmness fell into two groups. Firmness tests on samples of tomato fruit purchased from retailers suggested that all samples were adequately firm and had a firmness shelf‐life of at leas

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290607

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe component acids of lipids extracted from the liver of roach, powan, brown trout, perch, pike, sea trout, salmon, ice fish, dog fish and cod, the flesh of capelin, haddock, herring and mackerel, and the digland of octopus have been examined. Differences between lipids from freshwater and marine sources and between those obtained from male and female species are noted. Particular attention is directed to a group of furan‐containing acids present at low levels (up to 5%) in most of the samples. These unusual acids tend to concentrate in the cholesterol esters. In two starved cod the proportion of furanoid acids rose dramatically to 34 and 48% respectivel

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290608

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractAssuming a random distribution of Cys residues within a glutenin polypeptide chain it has been calculated that about one sixth of an average chain (allowing for an intra‐chain SS loop) would be available for unfolding under stress. It is postulated that, because the unfolding of chains under stress has a magnifying effect on the effective molecular length of glutenin, a comparatively small range in the average number of chains per molecule (DP) is sufficient to encompass the levels of dough tenacities encountered in practice. Since the DP depends inversely on the concentration of Theologically active SH groups, according to the linear glutenin hypothesis, an explanation is provided for the great sensitivity of doughs to reducing agents and improvers, and for the indifferent correlation of dough properties with flour SH conten

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290609

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe apparent viscosities of dilute solutions ofK‐carrageenan and sodium carboxymethylcellulose have been measured and the intrinsic viscosities calculated. Added glucose, sucrose and glucose syrup increase the apparent viscosities of the solutions but give lower values for the intrinsic viscosity. In the presence of glucose syrup the macromolecules exhibit the behaviour associated with neutral macromolecules. This is attributed to the presence of inorganic cations in the glucose syrup which, by interaction with the polyanion, prevent dissociation of the ionic groups in the polysaccharide

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290610

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe gum exudate ofKhaya grandifoliolahas only limited solubility in water. Analysis of the gum showed that approximately 50% was in the free acid form and the remainder was largely the calcium salt. The gum dissolves in sodium carbonate solution with removal of calcium ions. This significantly alters the viscosity of the solution but it may be controlled by addition of calcium ions.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740290611

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY