School of Life Science, Shanxi Engineering Research Center of Microbial Application Technologies, Shanxi Normal University, Taiyuan, 030031, Shanxi, People's Republic of China.
Bioprocess Biosyst Eng. 2024 Nov;47(11):1903-1914. doi: 10.1007/s00449-024-03076-3. Epub 2024 Aug 12.
Spray drying is an important industrial method for the preparation of B. thuringiensis powder from fermentation liquor. The effect of spray drying on the crystal proteins, however, has not been reported in the literature so far. The present study systematically investigated the effect of inlet air temperature, outlet air temperature, atomizing air pressure and additives (including organic and inorganic auxiliaries) on the thermal destruction of crystal proteins of B. thuringiensis. The results indicated that the content of crystal proteins of B. thuringiensis powder decreased with increased inlet air temperature, outlet air temperature and atomising air pressure. The pseudo-z values for inlet air temperature, outlet air temperature and atomizing air pressure were 826.4 ℃, 204.0 ℃ and 4.74 MPa, respectively. Among them, the outlet air temperature was a major parameter influencing the thermal destruction of crystal proteins, therefore, the decrease of the outlet air temperature was beneficial to increase the protein content in powder. Although the spray drying had an adverse effect on crystal proteins, the crystal protein content in spray-dried powder approached that in freeze-dried powder when the inlet air temperature of 165 ℃, outlet air temperature of 70 ℃ and atomizing air pressure of 0.15 MPa were employed. The addition of some organic and inorganic auxiliaries to fermentation liquor can protect the crystal proteins from heat damage.
喷雾干燥是从发酵液中制备苏云金芽孢杆菌粉末的重要工业方法。然而，迄今为止，文献中尚未报道喷雾干燥对晶体蛋白的影响。本研究系统研究了进口空气温度、出口空气温度、雾化空气压力和添加剂（包括有机和无机助剂）对苏云金芽孢杆菌晶体蛋白热破坏的影响。结果表明，随着进口空气温度、出口空气温度和雾化空气压力的增加，苏云金芽孢杆菌粉末中晶体蛋白的含量降低。进口空气温度、出口空气温度和雾化空气压力的伪 z 值分别为 826.4℃、204.0℃和 4.74MPa。其中，出口空气温度是影响晶体蛋白热破坏的主要参数，因此降低出口空气温度有利于提高粉末中蛋白含量。尽管喷雾干燥对晶体蛋白有不利影响，但当进口空气温度为 165℃、出口空气温度为 70℃、雾化空气压力为 0.15MPa 时，喷雾干燥粉末中的晶体蛋白含量接近冷冻干燥粉末中的晶体蛋白含量。向发酵液中添加一些有机和无机助剂可以保护晶体蛋白免受热损伤。
