Effect of Freezing Temperature on Re-steaming Quality and Component Properties of Frozen Whole Wheat Steamed Bread

Abstract

The effects of different freezing temperatures (–20 ℃, –40 ℃, –80 ℃) on the re-steaming quality and component properties of frozen whole wheat steamed bread with different whole wheat flour replacement rates (30%, 50%, 100%) were analyzed. The results showed that the specific volume retention of the re-steamed whole wheat steamed bread was higher and the texture quality of the re-steamed whole wheat steamed bread was better with the lower freezing temperature and the faster freezing speed. Freezing temperature had no significant effect on the height/diameter ratio of frozen steamed bread with different whole wheat flour replacement rate. At –20 ℃, the hardness of frozen steamed bread with different whole wheat flour replacement rate was significantly higher than that of fresh steamed bread after re-steaming. At –80 ℃, the hardness of steamed breads is similar to that of fresh steamed bread after re-steaming. With the decrease of freezing temperature, the starch gelatinization enthalpy of frozen whole wheat steamed bread was lower, and the index value of starch gelatinization characteristics of 100% frozen whole wheat steamed bread was similar to that of fresh steamed bread, 30% and 50% whole wheat steamed bread were closer to that of fresh steamed buns at –40 ℃ freezing temperature. The lower the extractability of gluten protein was in frozen steamed buns at lower freezing temperature, the smaller the damage of gluten protein structure was. The damage to the internal microstructure of whole wheat steamed buns was smaller at lower freezing temperature, and its quality was closer to that of fresh steamed buns. In short, the lower freezing temperature is conducive to keeping the better quality of whole wheat steamed buns. To provide basis and reference for frozen whole wheat steamed buns processing and quality improvement.

Keywords

• freezing temperature
• frozen whole wheat steamed buns
• re-steaming quality
• component properties
• protein secondary structure
• microstructure