Research on Hard-Core of the Steamed Bread Caused by Microwave Heating

Microwave heating has been extensively used in the area of food handling, and many investigators have been studying the effect of microwave heating on the quality of food. However, the phenomenon concerning on the hard-cores in steamed breads caused by microwave heating is poorly understood. A series of experiments are designed in this paper to investigate the impact of microwave heating on the quality of steamed breads under different heating conditions. The experiment results show that the hardness and cohesiveness can be used to measure the hard-core of steamed breads. The mechanism of hard-core caused by microwave heating is discussed. According to the results of experiments, the hardness of the steamed breads increases with the increment of the power, the duration and the times of microwave heating. The cohesiveness of the steamed breads shows a trend, which drops at first, then increases, and decreases finally with the duration of microwave heating. According to the experiment data, a hard-core in a steamed-bread appears under the following conditions: when it is heated for 50s with the power of 900W when the overheating time is 20s, for 65s with the power of 720W when the overheating time is 25s, or for 80s with the power of 540W when the overheating time is 30s. Heated twice with the same heating time, the steamed bread begins to appear hard-core phenomenon under the following conditions: when it is heated for 55s with the power of 540W, for 40s with the power of 720W, or for 30s with the power of 900W.