Thermal phase transitions and mechanical characterization of Atlantic cod muscles at low and ultra-low temperatures

• Published in: Journal of food engineering 2014-05, Vol.128, p.111-118
• Main Authors: Tolstorebrov, I., Eikevik, T.M., Bantle, M.
• Format: Article
• Language: English
• Subjects: DSC; Foods; Gadus morhua; Glass transition; Marine; Mathematical analysis; Mechanical properties; Melting; Moisture content; Muscles; State (computer science); State diagram; Young’s modulus
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2013.12.025

•Thermal transitions of cod were determined in the range between 25 and −150°C.•The glass transition was found in the range between −84.2 and −69.6°C.•State diagram was obtained.•Young’s modulus, rupture stress were determined at freezing temperatures.•The brittle–ductile transition was explained by the glass transition. The glass transition of fresh cod were detected in the temperature range between −69.6 (1.5) and −84.2 (1.3)°C. The unfreezable moisture content was 5.1 (0.2)% wet basis (w.b.). The onset of ice melting was at −33.5 (0.6)°C. The state diagram was obtained as a consequence of using the Gordon–Taylor and modified Clausius–Clapeyron equations. The maximal freeze concentration was measured at 75.6% solids. The rupture stress and Young’s modulus increased linearly with the decreasing of temperature; their abrupt changes were observed between −80.0 and −85.0°C, when both values increased sharply and then were stable until −130.0°C. The rheological properties correlated with the thermal phase transition in the cod’s tissues, and with the water state in the product. The abrupt changes in rapture strength and Young’s modulus were related to the low temperature glass transition. The cod tissues in the glassy state showed only brittle properties.