title: On the water-holding of myofibrils: Effect of sarcoplasmic protein denaturation.
abstract: The role of heat-denatured sarcoplasmic proteins in water-holding is not well understood. Here we propose a new hypothesis that in PSE-like conditions denatured sarcoplasmic proteins aggregate within and outside myofilaments, improving the water-holding of denatured myofibrils. The process is compartmentalized: 1) within the filaments the denatured sarcoplasmic proteins shrink the lattice space and water is expelled; and 2) between the myofibrils and in the extracellular space, the coagulated sarcoplasmic proteins trap the expelled water from interfilamental space. The effect of sarcoplasmic proteins on the water-holding of myofibrils following incubation for 1h at 21 to 44°C was investigated. Our results were consistent with the new hypothesis. Myofibrils without sarcoplasm had the poorest water-holding. With increasing amount of denatured sarcoplasmic proteins, the water-holding of heat-denatured myofibrils improved proportionally. X-ray diffraction was used to measure the lattice space between the filaments. Precipitated sarcoplasmic proteins shrank (P<0.001) the lattice spacing by 6.3% at 44°C.
authors.affiliation: Department of Food and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland.
authors.forename: Jiao
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, SE 171 77 Stockholm, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Arner
authors.affiliation: Department of Food and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland.
authors.forename: Eero
authors.initials: E
authors.lastname: Puolanne
authors.affiliation: Department of Food and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland. Electronic address: per.ertbjerg@helsinki.fi.
authors.forename: Per
authors.initials: P
authors.lastname: Ertbjerg
mesh_terms: D000818:Animals; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008460:Meat; D009124:Muscle Proteins / Q000737:chemistry*; D009210:Myofibrils / Q000737:chemistry*; D011489:Protein Denaturation; D012519:Sarcoplasmic Reticulum / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D009124:Muscle Proteins; D014867:Water
keywords: Heat denaturation; PSE; Protein aggregation; Water-holding capacity; X-ray diffraction