Gelling properties of vacuum-freeze dried surimi powder as influenced by heating method and microbial transglutaminase

Effects of heating method and addition of microbial transglutaminase (MTGase) on properties of gels made from vacuum-freeze dried silver carp surimi were investigated. After vacuum-freeze drying, surface hydrophobicity of surimi proteins obviously increased, Ca2+-ATPase activity slightly decreased, while α-helix percentage significantly decreased, indicating the surimi proteins were partially denaturated. Consequently, the dried surimi formed gels (D gel) with significantly lower breaking force, penetration distance and water holding capacity as compared with those of gels made from frozen surimi (F gel) under all the heating methods. With addition of MTGase, breaking force of the D gels heated at 40 °C/60 min and 90 °C/30 min was not significantly different from those of F gels, while was slightly lower under the heating of 40 °C/60 min + 90 °C/30 min. After adding MTGase, water holding capacity of the D gel under 90 °C heating increased significantly, while the gels under the other heating methods slightly deceased. Heating method obviously influenced color parameters of D gels while MTGase addition did not. Setting (40 °C) and MTGase addition induced covalent cross-linking of myosin heavy chains of D gels. MTGase addition reduced the uniformity of the water distribution in D gels.