Impact of Pressure Reduction Rate on the Quality of Steamed Stuffed Bun

Effects of three pressure reduction rates (PRR) of 103 Pa s-1, 197 Pa s-1, and 347 Pa s-1 on temperature distribution and variation, moisture content, and sensory quality of steamed stuffed buns were investigated after vacuum cooling. The distributions and variations of surface temperatures were determined by the thermal infrared imaging method. The temperature profiles presented significant differences in the average cooling rates of the different parts, depending on the PRR. Results showed that the greatest mass loss of 8.1% and the shortest cooling time of 288 seconds were found with the quickest PRR of 347 Pa s-1, while the least mass loss of 5.96% and the longest cooling time of 955 seconds were observed in the case of the slowest PRR of 103 Pa s-1. The pressure reduction rates had little influence on the changes of moisture contents in the crumb and stuffing. The sensory quality scores of vacuum-cooled buns at 103 and 197 Pa s-1 were higher than those at 347 Pa s-1.