3.3. Transmission electron microscopy (TEM)Surimi gels with peanut oil have the highest breaking force(Fig. 1), while gels with corn oil have the lowest. Thus, gels withthese two type oils were selected for the TEM observation. Fig. 3shows the microstructures of surimi gels with peanut oil or cornoil in the concentrations of 10, 30 and 50 g/kg, respectively. Thecontrol was surimi gel without vegetable oil (Fig. 3a). The followingtypical surimi gel structures can be observed in all samples: acontinuous protein matrix permeated by oil droplets with differentsizes (Fig. 3). As oil concentrations increased in gels, the number ofoil droplets was increased. The sizes of peanut oil and corn oildroplets in diameter in surimi gels were 4.85 1.84 mm and4.92 2.22 mm, respectively. There was no significant difference inthe droplet size between peanut oil and corn oil. When fish oil wasadded into the surimi, different sizes of oil droplets were formed inthe gels due to different mixing speeds (Okazaki, Yamashita, &Omura, 2002).