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Post‐Mortem Changes in Extractability of Myofibrillar Protein from Chicken Pectoralis
Author(s) -
SAYRE R. N.
Publication year - 1968
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.1365-2621.1968.tb09084.x
Subject(s) - myofibril , myosin , chemistry , ionic strength , alkali metal , actin , residue (chemistry) , extraction (chemistry) , biochemistry , sarcoplasm , pectoralis muscle , chromatography , salt (chemistry) , biophysics , anatomy , biology , endoplasmic reticulum , organic chemistry , aqueous solution
SUMMARY Protein extractability from chicken pectoralis was measured after the muscle had aged in ice for various periods from 30 min to 24 hr post‐mortem. The extraction solution was KCl in phosphate buffer at pH 7.0 and ionic strength 1.0. Residue from the salt extraction was treated with 0.1 N NaOH to remove additional myofibrillar proteins and the remainder was considered stromal protein. Sarcoplasmic protein, non‐protein nitrogen and stromal protein remained constant for all aging periods at 33%, 16% and 7% of the total nitrogen, respectively, Myosin extractability decreased rapidly during the first 3–4 hr of aging while the alkali soluble protein increased and actomyosin was extracted at a low, constant level. Following 4–6 hr of aging the alkali soluble protein became constant, and actomyosin appeared in the extract in increasing quantities as myosin continued to decline. The sum of myosin, actomyosin and alkali soluble protein was constant for all aging times at 44% of ihe muscle nitrogen. Actomyosin formation was accompanied by increased hydration of the myofibrillar proteins as indicated by increased swelling of the residue from salt extraction with greater aging time. The initial accumulation of alkali soluble protein and subsequent release of actomyosin correspond to the time course of toughening and tenderization in chicken muscle. Both of these observations may reflect initial binding of myosin to the nonextractable thin filaments, followed by disintegration or detachment of these filaments from the Z membrane.