为研究渗透脱水后黑加仑浆果的微波真空膨化特性及其工艺参数确定,文章通过单因素试验,研究微波功率、真空度、初始含水率及处理量对黑加仑浆果膨化特性的影响;通过二次回归正交试验,分析微波强度、真空度、初始含水率、膨化时间与黑加仑浆果膨化率的关系,优化工艺参数。在微波真空条件下,黑加仑整果的体积膨胀过程有迅速增长和缓慢增加两个阶段,符合Exponent rise to maximum函数规律,每个因素对整果膨胀系数和动力系数的综合作用,决定微波真空膨化黑加仑整果膨化率;各因素对膨化率影响的主次顺序为膨化时间、真空度、微波强度、初始含水率。研究结果可为微波真空膨化浆果的工业化生产提供技术依据。
To improve the industrial utilization of corn soaking water, the yeast protein powder was produced by microwave-assisted foam drying. Firstly, preparation experiments were carried out, which included the foaming characteristic experiments of fermentation broth and that about the effects of carbon and nitrogen ratio on solid content in the fermentation broth. Secondly, the drying characteristics experiment of corn soaking water was studied, which selected the microwave power, material amount and thickness as the influencing factors for the single experiment. The results showed that the final moisture content (d.b.) and drying rate were significantly affected by those factors.
Li QiangSun YuXu Xiang-wenZhang Qin-qinZheng Xian-zhe
Process parameters of microwave assisted extraction (MAE) of the polysaccharides from pumpkin viz. extraction temperature, time and liquid-solid ratio were studied by using single factor and response surface methodology method. The results showed that the liquid-solid ratio was the most important factor in polysaccharides yield, followed by extraction time, and the extraction temperature was the least important factor. The optimum microwave assisted extraction conditions for the highest polysaccharides yield from pumpkin (16.76%±0.38%) were obtained by using the response surface methodology with extraction time of 29 min, an extraction temperature of 79℃ and a liquid-solid ratio of 22 mL · g-1. Validation experiment result well agreed with predicted value.
ZHENG Xianzhe YIN Fangping LIU Chenghai XU Xiangwen
The kinetic mechanism for the preparation of silymarin from milk thistle seeds was studied during the microwave-assisted extraction (MAE) process. The results showed that the transfer rate of silymarin from milk thistle seeds increased with the microwave output power and temperature during MAE processing. The apparent extraction rate constant k (s-1) was 1.2028×10-2 , 1.2248×10-2 , and 1.2485×10-2 , and diffusion coefficient D (m2·s-1 ) was 4.21×10-10, 4.29×10-10 , and 4.37×10-10 at the microwave temperatures of 383, 393, and 403 K, respectively, in the silymarin MAE process. With the help of scanning electron microscopy (SEM), the microstructures of the samples extracted by MAE were observed. The results revealed that the increased efficiency and rate of MAE of silymarin could be attributed mainly to the subsequent cell change resulting from superheating effects during MAE.
