title: Raman spectroscopic study of structural changes in Hake (Merluccius merluccius L.) muscle proteins during frozen storage.
abstract: This paper examines changes in the structure and functionality of fish muscle proteins at frozen storage temperatures known to render very different practical storage lives (-10 and -30 degrees C). Apparent viscosity and dimethylamine (DMA) content showed drastic temperature-related differences during storage. Raman spectroscopy revealed the occurrence of some structural changes involving secondary and tertiary protein structures. The changes in secondary structure were quantified, showing an increase of beta-sheet at the expense of alpha-helix structure. The nuC-H stretching band near 2935 cm(-)(1) increased in intensity, indicating denaturation of the muscle proteins through the exposure of aliphatic hydrophobic groups to the solvent. These structural changes were more pronounced at -10 degrees C but occurred at both storage temperatures, whereas changes in apparent viscosity and DMA only occurred in storage at -10 degrees C. The possible utility of these structural changes for quality assessment is discussed.
authors.affiliation: Instituto del Frío (CSIC), Jose Antonio Novais, 10, Ciudad Universitaria, 28040 Madrid, Spain, and Instituto de Estructura de la Materia (CSIC), Serrano 121, 28006 Madrid, Spain.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Herrero
authors.forename: Pedro
authors.initials: P
authors.lastname: Carmona
authors.forename: Mercedes
authors.initials: M
authors.lastname: Careche
mesh_terms: D000818:Animals; D004123:Dimethylamines / Q000032:analysis; D005399:Fishes; D005519:Food Preservation; D005615:Freezing; D009124:Muscle Proteins / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013059:Spectrum Analysis, Raman; D014783:Viscosity
chemical_list: D004123:Dimethylamines; D009124:Muscle Proteins; C034516:dimethylamine