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Molecular Properties of Post‐Mortem Muscle. II. Phase Microscopy of Myofibrils from Bovine Muscle
Author(s) -
STROMER MARVIN H.,
GOLL DARREL E.
Publication year - 1967
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1967.tb01323_32_3.x
Subject(s) - tris , myofibril , hydroxymethyl , glycerol , sucrose , chemistry , fragmentation (computing) , chromatography , anatomy , biochemistry , biology , stereochemistry , ecology
SUMMARY— 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.