title: Decreased gelling and emulsifying properties of myofibrillar protein from repeatedly frozen-thawed porcine longissimus muscle are due to protein denaturation and susceptibility to aggregation.
abstract: The effects of freeze-thaw cycles (FT, 0, 1, 3 and 5 times) on protein functional properties of porcine longissimus muscle were investigated. FT increased gapping between muscle fibres and tore muscle fiber bundles. Myofibrillar protein (MP) isolated from FT muscle showed an increased hydrophobicity (P<0.05), reduced thermal transition temperatures (T(max)) and enthalpy of denaturation (DeltaH) (P<0.05), and enhanced susceptibility to thermal aggregation. These structural changes resulted in major losses in protein functionalities, e.g., 41-43% reductions (P<0.05) in MP emulsifying capacity and emulsion stability after five FT cycles. The ability of MP to form a viscoelastic gel network, as analyzed by small-strain oscillatory rheological testing, also attenuated with FT cycles. The FT process lowered (P<0.05) water-holding capacity (WHC), whiteness, and texture (hardness, springiness, chewiness and cohesiveness) of MP gels. Overall, repeated FT had a detrimental effect on the general functionality of porcine MP, and protein denaturation and aggregation were implicated in the functionality losses.
authors.affiliation: College of Food Science, Northeast Agricultural University, Harbin, Heilongjiang 150030, China.
authors.forename: Xiufang
authors.initials: X
authors.lastname: Xia
authors.forename: Baohua
authors.initials: B
authors.lastname: Kong
authors.forename: Youling
authors.initials: Y
authors.lastname: Xiong
authors.forename: Yanming
authors.initials: Y
authors.lastname: Ren
mesh_terms: D000818:Animals; D004044:Dietary Proteins; D004655:Emulsions; D005511:Food Handling; D005615:Freezing; D005782:Gels; D057927:Hydrophobic and Hydrophilic Interactions; D008460:Meat / Q000592:standards*; D009124:Muscle Proteins / Q000737:chemistry*; D018482:Muscle, Skeletal / Q000737:chemistry*; D011489:Protein Denaturation; D013552:Swine; D013696:Temperature
chemical_list: D004044:Dietary Proteins; D004655:Emulsions; D005782:Gels; D009124:Muscle Proteins