结晶场对蔗糖晶体着色的影响及其机理探讨

The Effect of Crystallization Field on Sucrose Crystal Colouration and Its Mechanism Exploration

研究发现:蔗糖晶体对色素具有选择性,其选择顺序是还原糖氨基酸褐变产物>酚铁络合物>焦糖;晶体着色受结晶场的制约,缓慢结晶以吸附形式着色、中速结晶以吸附形式为主并伴有包裹形式着色、高速结晶以包裹形式着色为主;在特定结晶场内有临界结晶速度存在,处于此速度下,晶体着色最少;糖厂甲膏的结晶速度因操作阶段而异,上述三种速度均可出现,但以全罐而言,属于中速结晶范围,晶体着色仍以吸附形式为主。通过上述研究,在机理上探明糖厂白砂糖着色以吸附形式为主。据此可找到降低砂糖色值的有效途径:力求减少煮糖原料中的色素量和易被吸附的色素(如还原糖氨基酸褐变产物);尽量控制在着色量最少的临界结晶速度下操作;可利用临观结晶速度粗略地推算出煮糖最适时间,力争在最适时间内完成煮糖任务,以减少砂糖着色。

It is detected by the research that the sucrose crystal has electivety to the colourants,the elective order is R.S.-amino acid browning reaction products>Phenol-ferrous complex>Caramel.The colouration of the crystal is restricted by the crystallization field.Under slow crystallization rate, colouration is mainIy caused by adsorption ; when the crystallization rate increases,this main way is accompanied by occlusion;under the high crystallization rate,the main way of colouration is replaced by occlusion. There is a critical rate within the crystallization field,under this rate,the colouration is the least.The crystallization rate of “A”massecuite varies with different boiling steps and three rates mentioned above all may appear. But,as far as its whole boiling process is concerned,the crystallization rate is medial and the main way of the colouration is adsorption. According to the theory that the main way of the colouration of the sucrose crystal is adsorption,we can work out an effective way for lightening the colouration:try the best to reduce the amount of the colourants, especially the colourants which is easyer to be adsorpted(such as the R.S. -amino acid browning reaction products),from the syrup material;try to control the sugar boiling process under the critical rate which would cause the least colouration;and,try to finish the sugar boiling within the suitable time which may be estimated by using the critical rate.