摘要:

AbstractA model system of egg albumin and herring oil was studied during storage at 21 ºC and ‐20 ºC. Chemical changes in the oil and protein were monitored by determinations of ether‐extractable lipid, iodine value, peroxide value, thio‐barbituric acid value, ultraviolet absorption of the oil,in vitrodigestibility and available lysine. The model system showed greater changes during storage with respect to both protein and oil than did either the albumin or the oil stored separately. Similar determinations were made on a freeze‐dried herring meal stored at 21 ºC in nitrogen and on a sample of the presscake (from which the meal was made) stored at ‐20 ºC.Available lysine level was a more sensitive criterion of protein alteration during storage than was pepsin‐digestibility. The absorption at 233 nm of extractable lipid from both the model and the natural systems was associated with the loss in lysine availability during the storage period. Ultraviolet absorbance of the lipid more closely reflected the rate at which lysine availability declined than did TBA or

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250802

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractHerring meals prepared with and without the addition of 0.025% of 1,2‐dihydro‐6‐ethoxy‐2,2,4‐trimethylquinoline (EQ) were stored for ten months at ‐20 ºC and 21 ºC. Storage changes in the biologically determined energy and protein values of the meals were monitored and related to changes in the chemical characteristics of the meal. Antioxidant treatment stabilised the meal lipid against oxidative changes resulting in loss of solubility, decline in iodine value and formation of peroxides and malonaldehyde. The effect of storage temperature on the course of oxidation depended upon whether the meal was treated with EQ. Lipid in meals without EQ tended to show greater change early in the storage period at ‐20 ºC. Antioxidant‐treated meals showed protection of the protein against changes leading to reduced digestibility and lysine availability. Either antioxidant treatment or storage at ‐20 ºC protected the biological availability of the energy‐supplying nutrie

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250803

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe lignin content of 50 samples of five grasses of knownin vivodigestibility were determined by the methods of van Soest and Wine,1and of Edwards2which utilise the solubility of lignin in potassium permanganate and in HCl‐activated trigol, respectively, and of Christian3in which the sample is refluxed with acid detergent after treatment with 72% sulphuric acid without any preliminary extraction. Mean lignin values for the three methods were 4.97, 5.57 and 7.24 and the errors in predicting dry matter digestibility were ±3.9, ±4.5 and ±2.4, respectively. When compared with the error of ±2.1 previously obtained on the same samples with thein vitrotechnique of Tilley and Terry4only the method of Christian3appeared favou

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250804

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractAcid detergent fibre was determined on 50 grass samples of knownin vivodry matter digestibility with and without a preliminary extraction with neutral detergent. Pretreatment with neutral detergent reduced the mean yield of acid detergent fibre from 41.5 to 36.8%. This decrease in acid detergent fibre was mainly due to a reduction in the level of ash which accounted for 57% of the difference in fibre level.The error in predicting dry matter digestibility of all feeds from acid detergent fibre was ±3.5 digestibility units and was increased to ±3.8 units following neutral detergent pretreatment. When acid detergent fibre was expressed on an ash‐free basis the corresponding residual standard deviations were ±4.4 and ±4.5 units, respectively. It was concluded that a pretreatment with neutral detergent or expressing results on an ash‐free basis did not improve the accuracy in predicting dry matter digestibility from acid detergen

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250805

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe amino acid compositions of the seed meals of four varieties of yam bean and one variety of lima bean have been compared with the F.A.O.1standard.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250806

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractToughness in lamb is determined by the extent of cold shortening occurring during chilling, and thaw shortening induced during cooking.Cold shortening sufficient to cause toughening is avoided by placing pre‐rigor carcasses in a standing posture. Muscles are then largely restrained from shortening, though stimulated to do so by cold.Thaw shortening with its potential to toughen is eliminated as a problem merely by holding frozen lamb in storage (‐12 ºC) for 20 days or more.These techniques for avoiding cold and thaw shortening can be compounded to form the basis of a simple processing method ensuring a uniform and high degree of tenderness, while still involving early freezing after slaughter. Carcasses are placed in a standing posture after dressing to prevent cold shortening during freezing. They are then held in frozen storage for a period to eliminate the possibility of thaw‐rigor shortening on c

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250807

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractToughness development in beef sternomandibularis muscle during cooking has been measured by a tenderometer, cleaving samples at right angles to the fibre direction. Since the muscles had been set in rigor mortis in an unshortened state, such toughening was not related to that induced by pre‐rigor contraction.Two distinctly separate phases of toughening develop with increasing cooking temperature. A three‐ to fourfold toughening occurs in the first cooking phase between 40 and 50 ºC, followed by a further doubling in the second phase between 65 and 75 ºC. The first phase is associated with loss of myosin solubility, presumed to indicate denaturation in the contractile system. The second is closely associated with collagen shrinkage. This apparently induces shortening along the meat fibre, forcing out meat

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250808

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractCooking loss has been studied in beef rectus abdominis and sternomandibularis muscles. The form of these muscles, the first a flat sheet and the second a rod of elliptical cross‐section, both bounded by intact surfaces, has allowed systematic patterns of cutting, giving differing distances along the fibre between cut ends. The cooking loss increases as the distance between cut ends is reduced, and is similar in both muscles. Mince has a lower cooking loss than 1 cm or 2 cm slices. The evidence strongly suggests that loss is almost exclusively along the fibres to the cut ends. The greatest loss is in the 2 cm adjoining the cuts. The large variation in loss with length is not reflected in the shortening along the fibre during cooking, which remains close to 25% irrespective of length.The lower loss in longer pieces of M. sternomandibularis is associated with a slightly higher level of tenderness. Freezing increases cooking loss in 4 to 16 cm lengths but not in shorter pieces or minc

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250809

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractA method is described for the prediction of thein vivodigestibility (d.m.d.) andin vivocell wall digestibility of grasses: it involves incubating grass cell walls with a commercial cellulase for 16 h and measuring the optical density of the filtrate at 324 nm (O.D.). The prediction equation is based on a highly significant correlation (r= 0.978) between O.D. and d.m.d. using a total of 27 samples of three species of grass with d.m.d. between 60 and 83. The method could not be used for the prediction of d.m.d. of red clover and sainfoin due to their filtrates having low O.D. values. A second method for the prediction of d.m.d. of grasses is also described and is based on a highly significant correlation between d.m.d. and the percentage of cell walls digested by cellulase (r= 0.962): similar comparisons for the legumes gave lower correlation coefficients. Using either the O.D. or gravimetric method, inclusion of cell wall content in the regression equations reduced the S.D. of d.m.d. predictions.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250810

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractSeed hulls from both sweet and bitter varieties of lupins (Lupinus angustifolius) have been analysed for constituent polysaccharides. The hulls contained 15 to 32% oxalate‐soluble pectic polysaccharide, excluding pentose, 12 to 14% hemi‐cellulose, 44 to 51% cellulose, 0.3 to 0.4% lignin, 2.7 to 3.8% protein and 2% ash. “Crude fibre” was 54.9%. In agreement with the low lignin values all of the hemicellulose was extractable with alkali without prior delignification and 70 to 80% of the polysaccharide in depectinated hulls was hydrolysed by cellulase plus hemicellulase, likewise without delignification. Sweet lupin seed hulls, added to a complete basal diet up to 40%, did not depress growth of young rats significantly; compensatory increase in food consumption occurred. With 60% hulls in the diet growth and food efficiency were reduced. Ground hulls did depress food and protein digestibility in direct proportion to their amount in the diet, possibly because of physical entrapment in the excessive bulk in the gut. The digestibility of the “crude fibre” of the hulls was 33% when the diet contained 20% hulls; this decreased to 22% when the content of hulls in the diet was incre

ISSN:0022-5142    

DOI:10.1002/jsfa.2740250811

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY