酶催化木薯淀粉表面松香酸酯化改性及表征

以木薯淀粉为原料,松香酸为酯化剂,氯仿为溶剂,以液态脂肪酶为催化剂,在两相体系中直接在原木薯淀粉表面进行酯化修饰合成松香淀粉酯(RAS),并利用傅里叶红外光谱(FT-IR)、电子扫描显微镜(SEM)、X-射线衍射(XRD)、热重差分析(TGA)、接触角、乳化能力及乳化稳定性等对RAS的结构及理化性能进行分析。结果表明:与原淀粉相比,FT-IR谱图中RAS在1728 cm^-1附近出现羰基特征峰,SEM图中RAS表面的酯化斑点表明木薯淀粉表面成功接上了松香酸基团;XRD和TGA结果显示木薯淀粉经松香酸修饰后结晶度下降;对比原木薯淀粉,RAS(DS=0.0502)的接触角提高了63.40%,乳化能力、乳化稳定性分别由原木薯淀粉的1.53%、1.50%,提高至31.91%、23.08%。且随着DS的升高,RAS疏水性能及乳化性能也随之提高。

Enzyme-catalyzed Modification and Characterization of Rosin Esterification on Cassava Starch Surface

Cassava starch was used as raw material,rosin acid as esterifying agent,chloroform as solvent,and liquid lipase as catalyst to synthesize rosin starch ester(RAS)directly on the surface of native cassava starch in two-phase system.The structure and physical and chemical properties of samples were analyzed by fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),X-ray diffraction(XRD),thermo gravimetric analyze(TGA),contact angle,emulsifying ability and emulsion stability.The results showed that the characteristic carbonyl peak of RAS near 1728 cm-1 in FT-IR spectrogram and the esterified spots on the surface of RAS in SEM spectrogram indicated that the rosin acid group successfully attached to the surface of the cassava starch.XRD and TGA results showed that the crystallinity of tapioca starch decreased after modification with rosin acid.Compared with the native cassava starch,the contact angle of RAS(DS=0.0502)increased 63.40%.The emulsifying ability and emulsion stability increased from 1.53%and 1.50%of the native cassava starch to 31.91%and 23.08%,respectively.And as the DS increased,the hydrophobic properties and emulsifying properties of RAS also increased.