处理方法对超高压改性酸解玉米淀粉结晶结构的影响

Effect of Treatment Methods on Crystal Structure of Ultra-high Pressure Modified Acid-hydrolyzed Corn Starch

25℃条件下,质量分数30%的玉米淀粉悬浮液经2.0 mol/L盐酸溶液温和酸解24 h,得到酸解玉米淀粉。将酸解后的玉米淀粉配制成质量分数5%的淀粉悬浮液,在500 MPa压力下处理15min,然后分别立即处理、回生3 d(4℃)、冷冻(-20℃)及回生3 d后冷冻处理,最后再进行干燥处理。利用X射线衍射仪对样品的结晶度进行测定,结果表明:天然淀粉经过24 h的酸解之后相对结晶度有所提高,500 MPa高压处理酸解24 h的玉米淀粉,能使淀粉颗粒内部的大部分结构发生水合而被破坏,冷冻处理能强化这种破坏作用,但同时又形成了新的B型结晶结构,样品高压后回生3 d处理,可以使样品基本上恢复到高压之前的状态。在一定压力范围内,淀粉的高压水合是一个可逆过程。

The corn starch was hydrolyzed in 2.0 mol/L HCl at 25℃ for 24 h to obtain the acid-hydrolyzed corn starch. Acid treated corn starch-water suspensions （5%） were subject to high pressure treatment at 500 MPa for 15 min. The samples were dried after being immediately treated, retrograded for3 d （4℃）, freezed （ -20℃ ） for24 h and retrograded for3 d, and then freezed and dried. The X-ray diffraction was used to determine the crystallinity of UHT-treated samples. The result showed that the relative crystallinity of native starch was increased in a certain extent after treating by acid for 24 h. The most structures in acid-hydrolyzed starch （24 h） granules were destroyed as a result of hydration after acid-treating at 500 MPa for 24 h. Freeze treatment could intensify this action while form new B-type structure. The Ultra-high pressure samples were stored for 3 d, and the state of starch could comeback basically. The process of high pressure hydration was reversible in a certain range of pressure.