水剂法提取油茶籽油形成的乳化液中 蛋白的分离及其结构表征Structural characteristics of proteins derived from the emulsion formed during aqueous extraction of oil-tea camellia seed oil

Abstract

水剂法提取油茶籽油时产生严重的乳化，是制约其应用的“瓶颈”。为明确其乳化液产生机制，对水剂法提取油茶籽油产生的乳化液中主要蛋白进行了分离与结构表征。结果表明：提取的粗蛋白在pH 2.0、4.0、6.0、8.0和pH 10.0条件下均表现优良的乳化特性；经初步纯化的蛋白组分（PEP）主要为7个分子质量为10～35 kDa的条带，其中13 kDa蛋白最多；PEP中谷氨酸、精氨酸和天冬氨酸含量较高，分别为（40.36±0.14）%、(14.51±0.09)%、(7.74±0.03)%；二级结构中α-螺旋、β-折叠、β-转角和无规卷曲含量分别为25.71%、31.55%、19.07%和23.83%，其中β-折叠含量最高；PEP溶液具有较高的内源荧光强度和表面疏水性。推测PEP为水剂法提取油茶籽油过程中乳化液形成的重要因素之一。It is unavoidable emulsification in the process of aqueous extraction of oil-tea camellia seed oil. To explore the generative mechanism of emulsion, the proteins in the oil-tea camellia seed oil emulsion were separated and its structural characteristics was investigated. The results showed that the crude proteins separated from the emulsion had excellent emulsifying properties at pH 2.0,4.0,6.0,8.0 and pH 10.0. The purified proteins(PEP) were seven major subunits/proteins with a molecular weight arranged from 10 kDa to 35 kDa, among them, the 13 kDa protein was the most. The PEP was rich in Glu, Arg and Asp, and their contents were (40.36±0.14)%, (14.51±0.09)% and (7.74±003)%, respectively. The contents of α-helix, β-folded, β-corner and random coil in PEP were 25.71%, 31.55%, 19.07% and 23.83%, respectively, among which the content of β-folded was the most. Moreover, the solution of PEP exhibited a high endogenous fluorescence intensity and surface hydrophobicity. It is hypothesized that the PEP is one of the important factors in the formation of emulsion during the extraction of oil-tea camellia seed oil by aqueous method.

Keywords

• 水剂法；油茶籽油；乳化液；蛋白；结构特征
• aqueous extraction; oil-tea camellia seed oil; emulsion; protein; structural characteristics