Zhongguo youzhi (Sep 2022)
醇洗前处理对樟树籽仁分离蛋白产品 及其蛋白质结构的影响Effects of ethanol washing pretreatment on camphor seed kernel protein isolate and its protein structure
Abstract
为解决樟树籽蛋白色泽深、纯度低的问题，将樟树籽脱壳、冷榨脱脂、粉碎后制得脱脂樟树籽仁粉，经不同体积分数乙醇前处理后，用碱溶酸沉法制备樟树籽仁分离蛋白（CPI）。对CPI的白度值、纯度、溶解度、分子质量和结构进行分析。结果表明：经55％～85％乙醇前处理，CPI色泽明显改善，其中经65%乙醇前处理后制备的CPI白度值由（0.70±0.02）%提高至（6.00±0.02）%；经95%乙醇前处理，CPI纯度由（60.61±0.35）%提高至（87.45±0.14）%；经85%乙醇前处理，CPI的溶解度由（81.87±0.15）%提高至（92.12±0.16）%，而经95%乙醇前处理后其溶解度下降至（62.72±0.05）%；CPI的分子质量主要分布于48、13 kDa和35 kDa，醇洗前处理后，分子质量为15 kDa的亚基消失，250 kDa的聚合体含量减少（除65％乙醇前处理的）。碱溶酸沉工艺导致蛋白质分子间的氢键被破坏，β-折叠和β-转角减少，无规卷曲和α-螺旋增加，而乙醇对CPI二级结构无明显影响。采用醇洗、碱溶酸沉的方法可制备色泽浅、溶解性好、纯度较高的CPI。 In order to solve the problem of deep colour and low purity of camphor seed protein, camphor seed kernel protein isolate (CPI) was prepared by alkali solution and acid precipitation method from dehulled, defatted with cold press and crushed camphor seed cake pretreated by different volume fractions of ethanol.The whiteness value, purity, solubility, molecular weight and structure of CPI were analyzed. The results showed that the colour of CPI was obviously improved after 55%-85% ethanol pretreatment. The whiteness value of CPI increased from (0.70±0.02)% to (6.00±0.02)% by 65% ethanol pretreatment. The protein purity of CPI increased from (60.61±0.35)% to (87.45±0.14)% by 95% ethanol pretreatment. After 85% ethanol pretreatment, the solubility of CPI increased from (81.87±0.15)% to (92.12±0.16)%, while after 95% ethanol pretreatment, the solubility decreased to (62.72± 0.05)%. The molecular weight of CPI was mainly distributed in 48, 13 kDa and 35 kDa.After ethanol washing pretreatment, the subunit with the molecular weight of 15 kDa disappeared, and the content of the polymer with the molecular weight of 250 kDa decreased(except that pretreated with 65% ethanol). The hydrogen bonds of protein molecules were destroyed, β-folding and β-turning structure decreased, and random crimp and α-helix structure increased by alkali solution and acid precipitation process, and the secondary structure of CPI was not significantly affected by ethanol. CPI with low colour, good solubility and high purity can be prepared by means of ethanol washing, alkali solution and acid precipitation.
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