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Dynamic rheological measurements on heat‐induced myosin gels: An evaluation of the method's suitability for the filamentous gels
Author(s) -
Egelandsdal Bjorg,
Fretheim Kristen,
Harbitz Ole
Publication year - 1986
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740370916
Subject(s) - rheology , rheometer , dynamic mechanical analysis , suspension (topology) , viscoelasticity , ionic strength , materials science , dynamic modulus , myosin , strain (injury) , slippage , phase (matter) , repeatability , analytical chemistry (journal) , rheometry , modulus , chemistry , chromatography , polymer , composite material , biochemistry , organic chemistry , anatomy , medicine , mathematics , homotopy , aqueous solution , pure mathematics
Formation of bovine myosin gels (10 mg ml −1 ) by heat treatment at pH 6 and an ionic strength of 0.24 M has been monitored by using the Bohlin Rheometer System in the oscillatory mode. Rheological thermograms were determined with a general repeatability of about 2% for a given suspension. A pronounced maximum and an accompanying minimum in storage modulus ( G ′) were found at about 50 and 55°C, respectively. The thermograms for the loss modulus ( G ″) and the phase angle (δ) displayed complex behaviour as well, suggesting a multitransition process. Presumably, denaturational events in parts of the molecule are responsible for the complex rheology observed. This complexity is not related to trivial wall slippage as data obtained from cells with different gap sizes were highly reproducible and consistent with other measurements. A decrease in heating rate from 2.5 to 0.1°C min −1 had a large effect on G ′; it increased from 905 to 1600 N m −2 for gels at 75°C. The phase angle was also affected by the heating rate, especially at about 55°C. The effect of increasing the strain from 0.003 to about 0.1 was significant in two temperature regions; G′ at temperatures higher than 65°C and δ at temperatures lower than 54°C increased with increasing strain.