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  • 1
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 32 (1967), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: SUMMARY— A study was made of the fine structure of myofibril suspensions prepared from seven heifers immediately after death and after various times post-mortem. Studies on myofibrils sampled immediately after death showed that sucrose isolation gave the best structural preservation as indicated by maintenance of Z-line structure. Although the appearance of resting muscle was maintained in both sucrose and KCI preparations, several myofibrils from the KCI-treated preparations showed stretched sarcomeres. Glycerol-treated myofibrils usually had shorter sarcomere lengths than myofibrils prepared with the other two solvents. Although fibrillar preservation seemed adequate when glycerol was used, Z-line structure was seldom well-preserved with glycerol.Myofibrils from muscle sampled 24 hr post-mortem at 2°C were supercontracted with thick filaments pushed against or through the Z-line, and no trace of l-bands remained. Myofibrils from muscle sampled 24 hr post-mortem at 16°C were contracted, but to a much lesser extent than 2°C-24 hr myofibrils. Storage at 2°C for 312 hr after death resulted in myofibrils that were contracted and that were structurally in a much poorer state of preservation than their 16°C counterparts. The 16°C-312 hr myofibrils were slightly contracted as indicated by the absence of H-zones and the presence of prominent, although narrowed, I-bands. All observations showed that shortening accompanying rigor mortis caused changes in banding patterns similar, and probably identical, to those predicted by Huxley's sliding filament model for contracting muscle.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: SUMMARY– Investigations were conducted on the effect of three storage temperatures, 2°, 16°, and 37°, on the changes and relationships of certain chemical and physical properties of post-mortem bovine semitendinosus and psoas muscle. Post-mortem muscle shortening was measured with the isometer. Isometric tension development was maximal at 2°, minimal at 16°, and at 37° tension was approximately one-half that developed at 2°. The large tension development at 2° very likely originates from the same events as those in “cold shortening.” Differences in isometric tension parameters were noted between muscles in that psoas muscle developed tension and lost the ability to maintain tension more quickly than did the semitendinosus. Loss of ability to maintain tension was observed only at 2°, and this could correspond to a “resolution” of rigor mortis. Adenosine triphosphate (ATP) degradation was measured by two methods, ammonia production and bioluminescent enzymic method; the bioluminescent method proved to be the more satisfactory. A common relationship was observed between pH and ATP for both muscles and the three temperatures studied. No direct relationship was found between ATP degradation and shear resistance with the possible exception of muscle stored at 37°. Isometric tension parameters and shear resistance were related somewhat at 2° in semitendinosus muscle, but no relationship existed at 16° and 37°. Although considerable tension developed in psoas and semitendinosus muscle at 37°, shear resistance values decreased continuously, indicating that factors other than shortening are more important at high temperature and that these factors are temperature-dependent.The role of ATP degradation in tension development was difficult to interpret, since at 2°, only a small change occurred in ATP level during large tension development, and the level of ATP at 2° did not differ from ATP level in muscle stored at 16° which developed little tension.Differences in post-mortem muscle shortening at 2 and 37 are discussed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 28 (1963), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Age-associated changes in the chemical composition of bovine biceps femoris muscle were studied. Veal muscle had significantly lower Kjeldahl nitrogen and higher moisture contents than muscle from the three older age groups studied. Muscle from veal and from the oldest group (cows, 10 years) possessed less fat than muscle from the two intermediate groups (steers, 1–2 years, and cows, 5 years). A modified procedure for determination of hydroxyproline and its use directly on mean hydrolysates are described. Use of this technique failed to reveal any significant differences in the hydroxyproline content, and presumably the connective-tissue content, of muscle from the four groups. Warner-Bratzler shear-force values of cores from biceps femoris steaks from the three oldest groups indicated that tenderness decreased with age. A method is given for isolation of large quantities of connective tissue from biceps femoris. Chemical analyses of these connective-tissue residues are presented, and the possibility is discussed that the veal connective tissue contains large amounts of reticulin.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 35 (1970), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: SUMMARY– Effects of postmortem storage of rabbit muscle at 25° on the properties of α-actinin and tropomyosin-troponin-containing fractions prepared from this muscle were studied. Postmortem storage did not affect the amount of α-actinin or tropomyosin-troponin that could be extracted from rabbit myofibrils by water washes or by a 3-day, pH 8.5, low-ionic strength extraction. Myosin B prepared from postmortem muscle underwent turbidity development much faster than myosin B prepared from muscle immediately after death. This increased rate of turbidity development was probably not due to postmortem changes in α-actinin, since the ability of α-actinin to accelerate the ATPase (for abbreviations used in this paper, see list under References) activity or the turbidity response of reconstituted actomyosin suspensions gradually decreased, rather than increased, during postmortem storage. However, even after 14 days postmortem at 25°α-actinin retained some activity in both the ATPase and turbidity tests. Moreover, the increased rate of turbidity development of postmortem myosin B was probably not due to degradation of the tropomyosin-troponin complex, since postmortem storage affected the activity of this complex only slightly and, even after 14 days post-mortem, the tropomyosin-troponin complex still conferred some Ca++-sensitivity on reconstituted actomyosin suspensions. Myosin B prepared from postmortem muscle did not contain more active α-actinin than myosin B prepared from muscle immediately after death, but the F-actin-tropomyosin-troponin interaction was gradually weakened during postmortem storage without any evident degradation of F-actin and the tropomyosin-troponin complex themselves. The weakened F-actin-tropomyosin-troponin interaction probably caused loss of Ca++-sensitivity in myosin B prepared from postmortem muscle. Results of this study indicate that postmortem changes in α-actinin and the tropomyosin-troponin complex per se are not the primary cause of postmortem modification in the actin-myosin interaction.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: SUMMARY– A study was done on the effects of in vitro storage of purified α-actinin, troponin, tropomyosin, and the tropomyosin-troponin complex on the activity of these protein fractions in the ATPase and superprecipitation assays. Storage was done at various combinations of temperatures between 0 and 40°C and pH values between 5.7 and 7.0. Even after 40 hr of storage, activities of purified tropomyosin and the tropomyosin-troponin complex were not affected by any combination of temperature and pH included in this study, but activities of purified α-actinin and troponin were almost completely lost after 16 hr at 40°C and pH 5.7. Storage for 40 hr at low pH (5.7) and low temperatures (0°C) did not affect the activity of either α-actinin or troponin, but 40 hr of storage at high temperatures (40°C) and neutral pH caused some loss in activity for both these proteins. This loss of activity caused by 40°C, pH 7.0 storage was much more noticeable in the case of troponin than in the case of α-actinin. Storage periods of 40 hr or longer were required before any loss of α-actinin activity could be detected at pH 7.0 and 40°C. Since most meat animal carcasses are chilled soon after exsanguination and attain muscle temperatures of 25°C or lower before the pH falls below 6.2, it is probable that α-actinin and tropomyosin-troponin activity remain almost unchanged in meat handled through normal market channels. However, myofibrillar tissue in those porcine animals whose musculature undergoes a very rapid post-mortem decline in pH so that values of 5.7 or less are reached while muscle temperatures are still 37°C or higher may lose much of its α-actinin and tropomyosin-troponin activity during the first 24 hr post-mortem.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 48 (1983), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The accuracy and precision with which Ca++-dependent proteinase (CAF) activity can be assayed in skeletal muscle tissue was determined by using two experimental approaches: (1) repeated sampling of a homogeneous batch of minced rat skeletal muscle to estimate variation among CAF assays done on fractions made from the same muscle tissue and to ascertain the effect of sample size on assays of CAF activity; and (2) comparison of CAF assays done on muscle samples of similar weights obtained from different animals that had been treated alike. Muscle CAF activity can easily be detected in 0.5g muscle samples, but the measured activity is not accurate and increases with increasing sample size. The decreased CAF activity assayed in small muscle samples seemed to originate from failure to extract all the CAF in these samples, possibly because of the different homogenizer that must be used to homogenize small samples. If a Waring Blendor is used at 8000 rpm, muscle samples must be 19g or larger to obtain accurate assays of CAF activity. The coefficient of variation for duplicate assays of CAF activity on the same P045 crude CAF fraction was 5.85% (assay variation); for assays of CAF activity on different samples of the same muscle tissue, 7.18% (sampling variation and variation in procedure for preparing crude CAF fractions); and for assays of CAF activity on muscle tissue obtained from the different groups of animals that had been treated alike, 10.30% (animal variation). Hence, CAF activity can be measured with acceptable precision in skeletal muscle tissue, but treatments designed to alter muscle CAF activity must cause changes of at least 20% to be detectable against the natural variation of muscle CAF activity in different animals.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 37 (1972), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 32 (1967), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The structural appearance of homogenized myofibril suspensions from seven heifers was studied using phase microscopy at various times post-mortem with three different extracting solutions: 1) 0.25M sucrose, 1mM ethylenedi-aminetetraacetic acid (EDTA), 0.05M Tris-(hydroxymethyl) aminomethane (Tris), pH 7.6; 2) 0.15M KCI, 1mM EDTA, 0.05M Tris, pH 7.6; and 3) 50% glycerol, 1miZl EDTA, 0.05M Tris, pH 7.6. Samples were examined at death and 24 hr and 312 hr post-mortem with storage at 2 and 16°C. The 16°-24-hr samples exhibited a marked thickening of the A-band, a shortening of the l-band, and a replacement of the H-zone by a dark line or band. The 2°.24-hr samples showed only alternating light and dark bands of nearly equal width, which has been described as a typical supercontracted pattern. At 312 hr, more variability in banding pattern and fragmentation is encountered, but the trend is to preserve the pattern observed in the 24.hr samples. Occasionally, a narrow H-zone is seen in the center of a thickened A-band in the glycerol preparations sampled 312 hr post-mortem. The results suggest that cold shortening of bovine muscle is structurally identical to contraction and substantiate the view that shortening is minimal at 16° storage temperatures.The sucrose extracting solution consistently gave the best preservation and was used for subsequent experiments. Although banding patterns at death and in the 24-hr samples obtained with glycerol showed reliable consistency, these preparations at times exhibited a disturbing fuzziness. Results with KCI solutions were least desirable, because of repeatedly poor structural preservation, as indicated by variability in sarcomere lengths within and between fibers, as well as lack of clarity in banding.
    Type of Medium: Electronic Resource
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