摘要:

ABSTRACTSarcoplasmic reticulum was isolated from P. major (white) and B. femoris (red) and assayed for calcium uptake and ATPase activity. The activities did not decline at 4 hr postmortem (rigor onset) and only slightly decreased with 24 hr aging. The prerigor P. major sarcoplasmic reticulum preparation had the lowest calcium uptake and ATPase activity, and mixtures of this fraction with others resulted in a lower activity than expected from the proportionate composition. Sarcoplasmic reticulum from B. femoris was affected more than that from P. major by decreasing temperatures. Freeze‐thawing the muscles did not destroy calcium uptake abilit

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1978.tb02387.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTIn order to test the hypothesis that the zinc to copper ratio is an important factor in determining the plasma level of cholesterol (Klevay, L.M. 1973. Am. J. Clin. Nutr. 26:1060–1068), White Leghorn laying hens were fed normal energy (2764 kcal/kg) and low energy (2470 kcal/kg) practical diets containing varied ratios of zinc to copper. The levels of zinc and copper used were selected such that neither was nutritionally limiting nor toxic. No significant differences were observed between the control diet (fed for 4 wk before commencing the actual experiment) or any of the experimental diets with the cholesterol levels averaging 13.3 mg/g for egg yolk and 84.1 mg% for the plasma example

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1978.tb02388.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTOne pass through a mechanical tenderizer improves the tenderness of Good grade beef semimembranosus roast. When comparing roast that had been tenderized four times with untenderized roast, cooking drip was increased (P<0.01), cooking evaporation was decreased (P<0.01) and cooking rate was faster (P<0.01). Both aerobic and anaerobic microbial numbers were higher (P<0.01 and P<0.05, respectively) for samples tenderized four times than untenderized controls or those tenderized one or two times. Taste panel acceptability at 4 wk was decreased (P<0.05) compared to acceptability at the initial period or following 2 wk of storage.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1978.tb02389.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTExperiments were designed to determine the effect of the chemical state of myoglobin and presence of ascorbate on the conversion of nitrite to nitrate. In model systems, nitrate was not formed when nitrite was incubated in the presence of either metmyoglobin or ascorbate. However, most of the added nitrite was converted to nitrate when both ascorbate and metmyoglobin were present. It is suggested that ascorbate reduces metmyoglobin to myoglobin, and then, the myoglobin is oxidized simultaneously with nitrite to form nitrate. In cured meat products, a detectable level of nitrate was formed in the absence of ascorbate, but in the presence of ascorbate the level of nitrate formed was greater. The explanation suggested was that endogenous reductants in meat could play the same role as ascorbate in model systems. Such endogenous reductants were responsible for more than half of the nitrate formation in meat products containing sodium ascorbate.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1978.tb02390.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTCervical, thoracic, lumbar and sacral vertebrae, plus rib and femur bones were removed from 13 bovine of a wide age range (89–2783 days) to elucidate changes in bone composition as a function of age and anatomical location. Percent dry matter, ash, calcium and phosphorus increased with age while nitrogen and sulfur decreased. The calcium/phosphorus ratio remained relatively constant during growth. Dry matter, ash, calcium and phosphorus percentages increased from the anterior to the posterior of the vertebral column, while sulfur and nitrogen decreased. Thus, bone ossification advanced from the posterior to the anterior vertebrae. The femur contained the largest proportion of ash, calcium and phosphorus of the six bone types investigate

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1978.tb02391.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTTwo preparatory techniques for electron microscopy were employed to investigate ultrastructural changes in bovine muscle during postmortem aging. The ultrastructural changes in aged muscle prepared by ultrarapid frozen thin sectioning procedures were less extensive than those observed in fixed, dehydrated, and embedded muscle, and this suggested that the preparation procedure may affect observed structural characteristics. The major changes observed in unfixed, frozen hydrated muscle were evident as alterations in electron scattering in the striations of the myofibrils indicating that ion redistribution occurred during postmortem aging. Structural alterations observed in aged tissue prepared by standard techniques included disruptions in the Z line, breaks at the Z‐I junction and fading or disappearance of the M lin

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1978.tb02392.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTEndocellular enzymes fromPseudomonas fragi(ATCC 4973) had a significant (P<0.05) effect on the color of sterile beef and sterile aqueous beef extract stored at 21°C and 4°C. There was no evidence of protein degradation or lipid oxidation in samples treated with endocellular enzymes. Our findings indicate that glucose oxidase present in the endocellular enzyme preparations fromP. fragimay be an important factor in causing oxidation of the meat pigment oxymyoglobin to metmyoglobi

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1978.tb02393.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTFactors influencing tyramine formation and the presence of tyrosine decarboxylase activity in natural microflora and starter (Pediococcus cerevisiae) fermented sausages were determined. Maximal levels of tyrosine decarboxylase were found during the period of rapid acid development in the natural microflora fermentations. Higher levels of decarboxylase were present in the natural fermented sausages compared to the starter fermented sausages. Tyrosine decarboxylase activity increased during the drying treatment in the natural microflora sausages but remained low in the starter fermented sausages. Greater tyramine contents were found in the natural microflora sausages which had free L‐tyrosine added prior to fermentation. Tyramine contents of the natural microflora and starter fermented sausages without added L‐tyrosine generally reached similar tyramine levels. In the starter fermented sausages, tyramine and tyrosine decarboxylase development comparable to the amounts found in natural microflora fermented sausages occurred only in a sausage which contained added L‐tyrosine that was inoculated with a tyrosine decarboxylase positiveStreptococcus faecalis. The study indicated that the natural meat microflora developed during the aging of salted meat can develop tyrosine decarboxylase activity necessary for rapid conversion of tyrosine to tyramine. The use of a starter culture such asP. cerevisiaeappears to decrease the possibility of development of a microflora during fermentation that would possess both tyrosine decarboxylase activity and proteolytic activity necessary to produce fermented sausages with potentially hazardous tyramine concentr

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1978.tb02394.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTThe protozoanTetrahymena pyriformisW was used to assess protein quality in two cultivars and three experimental lines of lentils. Cooked, freeze‐dried lentil powders and two protein fractions (legumin albumin) were evaluated and showed small but significant (P<0.05) differences. The protein in whole (nonfractionated) lentil powder supported 15–19% of the growth supported by the control protein, casein; two of the experimental breeding lines supported moreTetrahymenagrowth than did the cultivars. The albumin fractions supported almost three times more growth and the legumins supported slightly growth than did the lentil powders. Supplementation studies with intact lentil powders showed sulfur‐containing amino acids to be first limiting. Lentil powders with essential amino acids added to simulate casein produced less than half as much growth as did c

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1978.tb02395.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTBoth green beans and seeds formedn‐hexanol,n‐hexanal and 1‐octen‐3‐ol as the principal volatile compounds from U‐14C‐labeled linoleic acid but at proportionately different ratios. With U‐14C‐labeled linolenic acid, green beans developed mainlytrans‐2‐hexanal, 1‐penten‐3‐ol, 3‐penten‐1‐ol,trans‐2‐hexenol andcis‐3‐hexenol, while seeds produced largely 1‐penten‐3‐ol and 3‐penten‐3‐ol with a small amount oftrans‐2‐hexenal. Green beans showed the highest lipoxygenase activity of the several fruits and vegetables compared. Though alcohol oxidoreductase was relatively low, rapid reduction of aldehydes/ketones to alcohols was found in green beans. Green bean lipoxygenase was inhibited by cyanide and a small fraction appeared to be quite heat stable, compared to alcohol oxidoreductase which was much more unstable. The optimal acti

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1978.tb02396.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY