微波辅助萃取的微波吸收系数与吸收功率密度

1、 第 4期 韩光泽 等 : 微波辅助萃取的微波吸收系数与吸收功率密度 57 Absorption Coeff ic ien t and Absorption Power D en sity of M icrowave i n M icrowave2 A ssisted Extraction Han Guang 2ze Chen M ing 2dong Guo P ing 2sheng L i S hao2x in 1 1 2 1 ( 1. School of Physics, South China Univ . of Tech. , Guangzhou 510640, Guangdong,

2、China; 2. College of Physics and Electronic Engineering, Guangxi Nor mal Univ . , Guilin 541004, Guangxi, China Abstract: The absorp tion coefficient and absorp tion power density of m icrowave are two important physical quanti2 ties to esti m ate the efficiency of m icrowave 2assisted extraction. T

3、he former demonstrates the total p roportion of m i2 crowave energy absorbed by the solution, and the latter rep resents the conversion strength of ther m al energy from m icrowave energy at any space point in the solution. In this paper, on the basis of the p ropagation law of m icro2 wave, an exp

4、ression of absorp tion coefficient is derived as a function of solution perm ittivity . Then, according to the interaction bet w een m icrowave and solution, an analytical exp ression of absorp tion power density is also derived, which is a function of the perm ittivity and the space coordinates . T

5、he two p roposed exp ressions p rovide theoretical guidance for the selection of solvents in m icrowave 2assisted extraction and the selection of m icrowave frequency in a specified solution. Key words: m icrowave 2assisted extraction; absorp tion coefficient; absorp tion power density; m icrowave f

6、requency; dielectric constant (上接第 41 页 12 张本山 ,高大维 ,林勤保 , 等 . 高交联马铃薯淀粉非晶 of high cross2linking on non2crystallization of photo starch J . Journal of the Chinese Cereals and O ils A sso 2 ciation, 1999, 14 ( 1 : 19 222. 化特征研究 J . 中国粮油学报 , 1999, 14 ( 1 : 19 222. Zhang Ben 2shan, Gao Da 2 wei, L in Q

7、in2bao, et al . Effect Prepara tion of Non 2 Crysta l Granular Starch by A lcoholic2 A lka lin e Trea t m en t X u L i2hong Z hang B en 2shan Yang L ian 2sheng Gao D a 2 w ei 1 2 2 2 (1. School of Chem ical Science, South China Univ . of Tech. , Guangzhou 510640, Guangdong, China; 2. School of L igh

8、t Industry and Food Sciences, South China Univ . of Tech. , Guangzhou 510640, Guangdong, China Abstract: A method to p repare non 2crystal granular starches from maize starch by alcoholic 2alkaline treatm ent was reported. In the p reparation, native starches were first treated w ith the m ixture of

9、 ethanol and NaOH solution to s well starch granules . Next, the treated starches were neutralized. After being washed using ethanol solution w ith certain content, the starches were then dried to form non 2crystal granular starches . The structural change of the p roduct was finally observed by m eans of polarized m icroscope and XRD. It is concluded that non 2crystal granular starches can be p repared by treating the starches in al