元宝枫籽蛋白的营养性及理化性质

Nutritional and Physicochemical Properties of Acer truncatum Seed Protein

以元宝枫籽为原料,分别采用碱溶酸沉法和盐提法提取元宝枫籽分离蛋白(Acer truncatum Bunge. protein isolate,ABPI)和盐提蛋白(A. truncatum Bunge.salt extractable protein,ABSPI),并对其营养性及理化性质进行对比研究。结果表明,ABPI和ABSPI中均含人体所需的8种氨必需基酸,其中谷氨酸是主要的氨基酸,且ABPI和ABSPI必需氨基酸含量分别占总氨基酸含量的37.86%和38.45%。ABPI的表面疏水性(664.86)、总巯基(35.79μmol/g)与二硫键(11.50μmol/g)含量显著高于ABSPI(P<0.05),且热变性温度(128.05℃)也高于ABSPI(118.33℃)。而ABSPI持水性(4.64 mL/g)显著高于ABPI(2.46 mL/g)(P<0.05),持油性(3.58 mL/g)低于ABPI(4.82 mL/g)。ABPI和ABSPI的起泡性、起泡稳定性及乳化性随pH值的变化趋势均相似。傅里叶红外光谱显示ABPI与ABSPI均有典型的蛋白吸收峰,但ABSPI可能不具有三螺旋结构。扫描电子显微镜结果表明,2种蛋白的微观结构明显不同,ABSPI呈有序簇状球形蛋白,而ABPI结构紧密,表面呈不规则山脊状。相比ABSPI,ABPI具有更好的理化性质和功能特性。

Acer truncatum Bunge. seed protein(ABPI) and salt extractable protein(ABSPI) were extracted from the seeds of A. truncatum Bunge. by using alkali dissolution acid precipitation method and salt extraction method, respectively. Their nutritional and physicochemial properties were compared. The results showed that both ABPI and ABSPI contained the eight essential amino acids(EAAs) with glutamic acid being the most abundant amino acid, accounting for 37.86% and 38.45% of the total amino acid content, respectively. The surface hydrophobicity(664.86), total sulfhydryl content(35.79 μmol/g) and disulfide bond content(11.50 μmol/g) of ABPI were significantly higher than those of ABSPI(P < 0.05), and the thermal denaturation temperature was 128.05 ℃, which was also higher than that of ABSPI(118.33 ℃). The water-holding capacity(4.64 mL/g) of ABSPI was significantly higher than that of ABPI(2.46 mL/g)(P < 0.05), while the oil-holding capacity(3.58 mL/g) was lower than that of ABPI(4.82 mL/g). The foaming capacity, foam stability and emulsifying properties of ABPI showed similar trends to ABSPI with pH. Fourier transform infrared(FTIR) spectroscopy showed that both ABPI and ABSPI displayed typical protein absorption peaks, but the tertiary structure of ABSPI was incomplete. The results of scanning electron microscopy(SEM) showed that the microstructures of the two proteins were significantly different. ABSPI showed an ordered cluster of globular proteins, while the structure of ABPI was dense tight and the surface was irregularly ridged. ABPI had better physicochemical properties and functional characteristics than ABSPI.