Decreased gelling properties of protein in mirror carp (Cyprinus carpio) are due to protein aggregation and structure deterioration when subjected to freeze-thaw cycles

• Published in: Food hydrocolloids Vol. 97; p. 105223
• Main Authors: Li, Fangfei, Wang, Bo, Kong, Baohua, Shi, Shuo, Xia, Xiufang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2019
• Subjects: Ca2-transporting ATPase; Cyprinus carpio; enzyme activity; fish; Freeze-thaw cycle; freeze-thaw cycles; frozen storage; gelation; gelling properties; Gelling property; gels; hydrocolloids; mechanical damage; Mirror carp; Myofibrillar protein; Protein structure; protein tertiary structure; solubility; Freeze-thaw cycle; Myofibrillar protein; Mirror carp; Protein structure; Gelling property
• ISSN: 0268-005X; 1873-7137
• DOI: 10.1016/j.foodhyd.2019.105223

The changes in the gelling property and structural integrity of mirror carp protein that was induced by freeze-thaw (F-T) cycles were discussed. The strength, whiteness and water-holding ability of myofibrillar protein (MP) gel, the solubility and Ca2+-ATPase activity of MP were all significantly reduced after 5 F-T cycles (P < 0.05). The transverse relaxation time peak (T2) of samples under repeated F-T cycles exhibited a significant redshift (P < 0.05). The MP film surface became rough and irregular, as observed using atomic force microscopy (AFM) during the multiple F-T cycles. Additionally, the state and the weight of molecular distribution evidenced that F-T cycles caused protein aggregation and mechanical damage. The alterations in primary, secondary and tertiary protein structure revealed that the protein structure integrity of fish was destroyed under repeated F-T cycles. These findings indicated that repeated F-T cycles should be avoided during the freezing storage of fish to improve gel quality and sustain protein structural integrity. [Display omitted] •Gel property and structural integrity of fish protein induced by F-T cycles were discussed.•The change of protein gel surface was observed by the atomic force microscopy.•The change of protein molecular weight was measured by size exclusion chromatography.•Decrease in fish protein gel property was explained by the protein structure change.•Mirror carp was avoided to subject repeated freeze-thaw during frozen storage.