Abstract:
Six different thawing methods, air thawing, low-temperature thawing, hot water thawing, ruuning water thawing, ultrasound thawing and microwave thawing were used, in order to investigate the effects of different thawing methods on the quality of frozen fish ball. In this study, the thawing time, water holding capacity, color, pH, total volatile basic nitrogen (TVB-N) content, thiobarbituric acid-reactive substance (TBARS) content, texture characteristics and microstructure were measured to evaluate the effects of thawing on frozen fish balls. The results showed that the microwave thawing could make the balls thawed rapidly, but the water holding capacity and texture index of the balls after thawing were poor, with local overheating being obvious. Ultrasound thawing led to a better water holding capacity, and its thawing loss, TVB-N content and TBARS content were being lower (only 2.60%, 3.85 mg/100 g and 0.54 mg MDA/kg, respectively). Compared with other thawing methods, low-temperature thawing had the lowest thawing loss and cooking loss (2.24% and 1.97%, respectively), with the hardness, springiness, gumminess and chewiness value being better than others. The results of scanning electron microscopy showed that the muscle structure of the fish balls thawed at a low-temperature was compact, with minimal damage. Air thawing promoted a high degree of protein degradation, with the TVB-N content being the highest (5.60 mg/100 g). The running water thawing also enhanced protein degradation and its TVB-N content was insignificantly different from that for air thawing. There were no significant differences in the color and pH among the fish balls thawed by different methods. Taken together, ultrasound thawing could maintain the water holding capacity and had a relatively smaller effect on protein and lipid, thus it was an ideal thawing method for defrosting fish balls. However, the parameters of ultrasound thawing still need to be studied. The low-temperature thawing led to a texture property, thus, may be suitable for normal cooking by consumers.
