【摘要】 以火龙果(Hylocereus polyrhizus)种子为材料,脱脂后分析其成分。采用Osborne分级分离法得到三种火龙果种子分离蛋白,检测其表面疏水性、巯基含量、热变性温度、氨基酸成分等理化性质,分析pH和NaCl浓度对火龙果种子分离蛋白的溶解性、持水性、发泡性、泡沫稳定性、乳化性、乳液稳定性等功能特性的影响。结果表明,火龙果种子脱脂粉中含量最高的三种成分为粗蛋白(51.04%)、粗纤维(23.60%)和总多酚(15.26%);火龙果种子中分离得到白蛋白、球蛋白和谷蛋白,提取率分别为19.51%、14.07%和32.29%;白蛋白由2个亚基组成(分子量23.4kD和14.2kD),球蛋白由3个亚基组成(分子量分别为21.7kD、18.7kD和15.2kD),谷蛋白由3个亚基组成(分子量分别为49.5kD、34.2kD和18.6kD);白蛋白、球蛋白、谷蛋白热变性温度分别为59℃、58℃和91℃;谷蛋白的表面疏水性(2730)最高;白蛋白的总巯基(5.38 mmol/L)和游巯基(2.35 mmol/L)含量最高;3种分离蛋白中谷氨酸和精氨酸含量较高。4≦pH≦6范围内3种蛋白的溶解性最低;pH=4时,3种蛋白的持水性(WHC)、发泡性(FC)、泡沫稳定性(FS)、乳化性(EC)和乳液稳定性(ES)最低。本实验为新蛋白质来源的功能性食品开发,以及火龙果经济价值的提升提供参考。更多还原

【Abstract】 The pitaya(Hylocereus polyrhizus) seeds were used as material, and its composition was analyzed after defatting it. Three kinds of isolated protein from pitaya seed were obtained using Osborne method. The surface hydrophobicity, sulfhydryl content, heat denaturation temperature, amino acid composition of the isolated protein were tested. The effects of pH and NaCl concentration on the solubility, water holding capacity, foaming capacity, foaming stability, emulsifying capacity, emulsifying stability of isolated protein were analyzed. The results showed that three components with the highest content in defatted powder of pitaya seed were crude protein(51.04%), crude fiber(23.60%), and total polyphenols(15.26%). The albumin, globulin and glutenin were isolated from pitaya seeds, and the extraction rates were 19.51%, 14.07% and 32.29%, respectively. The albumin was composed of 2 subunits(molecular weight 23.4kD, 14.2kD). The globulin was composed of 3 subunits(molecular weight 21.7kD, 18.7kD, 15.2kD). The glutenin was composed of 3 subunits(molecular weight 49.5kD, 34.2kD,18.6kD). The thermal denaturation temperature of albumin, globulin and gluten were 59℃, 58℃ and91℃, respectively. The surface hydrophobicity(2730) of glutenin was the highest; total sulfhydryl(5.38 mmol/L) and sulfhydryl(2.35 mmol/L) content of albumin were the highest. The glutamic and arginine content was high in three isolated proteins. The solubility of three isolated proteins at 4≦pH≦6 condition was the lowest. The water holding capacity(WHC), the foaming property(FC), the foam stability(FS),the emulsifying properties(EC) and emulsion stability(ES) of three isolated proteins were the lowest at pH =4. This experiment provided a reference for the development of functional foods with new protein sources and the improvement of the economic value of pitaya.更多还原