Abstract:The changes in the enzyme activity and structure of α-amylase/λ-carrageenan complex during freeze-thawing were studied. The influences of complex on the properties of frozen dough and the steamed bread were analyzed through the fermentation performance, pore size distribution, and texture. The results showed that the fluorescence quenching was observed after three cycles of freeze-thaw and the α-amylase activity was significantly decreased to 54%. The formation of α-amylase/λ-carrageenan complex could further reduce the enzyme activity. The addition of α-amylase effectively changed the quality of steamed bread, such as increasing the specific volume, reducing the hardness, and improving the elasticity. But the complex of λ-carrageenan/α-amylase insignificantly affected the texture of steamed bread. The number of pores in steamed bread treated with α-amylase and complex was significantly higher than that in blank group, but pore wall became thicker, indicating that α-amylase and complex made the internal structure of steamed breads finer and more stable. In summary, α-amylase/λ-carrageenan complex did not improve the quality of steamed bread as well as the addition of α-amylase alone. The polysaccharide was speculated to mask the activity site of α-amylase and weaken the improvement effect on the quality of steamed bread after the formation of α-amylase and λ-carrageenan complex.
