Abstract: In order to investigate the effect of konjac glucomannan (KGM) on the gelling properties of shrimp myofibrillar protein (SMP), composite gel systems were prepared with different ratios to KGM and SMP (1:50, 1:20 and 1:10, m/m), named as SK50, SK20 and SK10, respectively. The surface hydrophobicity, endogenous fluorescence, turbidity, particle size, rheological properties, Fourier transform infrared (FTIR) spectra, protein composition and microstructure of the composite systems were investigated. The results showed that the surface hydrophobicity, turbidity and particle size of SMP and SMP-KGM composite systems increases with increasing KGM addition. Rheological analysis showed that shear thinning occurred in both SMP and SMP-KGM composite systems, and the storage modulus (G’) value of SK20 was the highest, indicating that the gel network in SK20 had the highest structural stability. FT-IR analysis showed the characteristic spectral bands of SMP and SMP-KGM composite systems were similar. SDS-PAGE analysis showed that addition of KGM did not significantly change the bands of SMP. After heating, the band densities of myosin heavy chain, paramyosin and actin were significantly decreased compared with the unheated group, indicating that the three proteins underwent aggregation during heating. Scanning electron microscope and fractal dimension analysis showed the formation of a dense and ordered gel with increasing KGM content. In general, adding an appropriate amount of KGM can improve the gel strength, and the product quality of shrimp surimi.

Key words: Litopenaeus vannamei; myofibrillar protein; konjac glucomannan; gel properties; rheological properties