Fish muscle, rigor

Hudson, L., Harford, J. J., Denny, R. C., and Squire, J. M. (1997). Myosin head configuration in relaxed fish muscle Resting state myosin heads must swing axially by up to 150 A or turn upside down to reach rigor./. Mol. Biol. 273, 440-455. 

Fig. 15. Intensity profiles along the equator of the bony fish muscle low angle X-ray diffraction pattern from muscles at rest (A), fully active (B), and in rigor (C). The indexing in (A) is based on the hexagonal A-band lattice, and the arrows indicate peaks that come from the Z-band. (C) to (F) are computed electron density maps based on the amplitudes of the A-band peaks in (A) to (A), respectively. The simple lattice unit cell is outlined in (D). (From Harford and Squire, 1997.)...

Connective Tissue Proteins. Collagen comprises the major material of skin and myocommata. Love and his co-workers studied the problem of gaping in which slits or holes appear in the muscle and sometimes the fillet falls apart. This defect is related to the behavior of myocommata proteins (83-87). Gaping is more severe in fishes frozen in-rigor than in those frozen pre-rigor, and the seriousness of this defect varies with the biological condition of the fish (influenced by season, size, age, and whether the fish is healthy or starved), and the fish species. 

Based on a graphical deconvolution of spin-spin experiments, values of 230 m.sec (15%), 40 m.sec (65%) and 10 m.sec (20%) were obtained. Derbyshire and Duff report biphasic spin-spin decays in porcine muscle with relative fractions dependent on the degree of rigor ( ). Derbyshire and Woodhouse found complex relaxation in fish, porcine, frog and human muscle was confirmed by Hazelwood et al. (W and Pintar et al. (5). 

Martinsen et al. (2000) presented measurements of the electrical properties of haddock muscle from 1 Hz to 100 kHz as a function of time after the fish was sacrificed (Figure 4.28). Clear a- and (3-dispersions were found. Most of the a-dispersion disappeared after a few hours. The low-frequency resistance of the (3-dispersion increased during the first 5 h as the fish went into rigor and then decreased as cell destruction developed. 

Low field NMR has become a valuable tool in the research of muscle structure of meat and fish and has given valuable information about the water behaviour in such biological systems. The aim of this paper was to study the differences in farmed and wild cod muscle as indicated by low field relaxation measurements and how these results can be related to more traditional measurements of physical, chemical and sensory analysis and how different processing, such as filleting pre or post rigor mortis, salting and superchilling affected these parameters. 

Yield measurements could therefore be summarized by the facts that the best salt uptake was gained by salt injection and that salt addition was most effective in wild post rigor mortis cod muscle. Drip measurements also showed that superchilling had a positive effect on the yield, in correlation to slower spoilage mechanisms than in the chilled samples. Salt injections also showed some positive effect on the drip loss, especially in the pre rigor fish. 

The chemical spoilage indicators of total volatile base nitrogen (TVB-N) and trimethylamine (TMA) first became evident in the chilled samples on storage days 9-13 and not until on day 15 for superchilled pre rigor muscle (both salted and non salted). It could therefore be seen that superchilling had a positive effect on the slowing down the spoilage of the fish. 

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