大米中蛋白质含量测定方法初探
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摘要
大米蛋白是优质蛋白,然而,当前存在着严重的掺假现象。为降低生产成本,向大米产品中添加非蛋白含氮物质。采用大米蛋白作为研究对象,以尿素等为干扰物,利用Lowry、CBB、凯氏定氮法,研究干扰物对蛋白质含量测定方法的影响。研究发现,三聚氰胺的加入量低于300g/kg时,对测定结果无明显干扰作用,误差基本保持在3%以内;尿素的含量在低于100g/kg时,对测定结果无明显干扰作用,而随着加入量的继续增大,使CBB法和Lowry法的测定数据均有一定程度的下降,其中CBB法表现更为明显;硫酸铵对蛋白质含量的测定的影响最为微弱,添加量超过50g/kg时,蛋白质的测定结果反而呈现下降的趋势。分析表明,相比较凯氏定氮法、CBB法,Lowry法准确度更高,但由于蛋白质所含的氨基酸种类和比例不同,因而适合蛋白质的测定方法也不同,应根据情况选择最优方法,力求达到最佳效果。
Rice protein is a kind of high-quality protein. However, there is a serious adulteration phenomenon in the current dairy products and food raw materials. In order to reduce production costs, some companies and businesses add non-protein nitrogen material to rice products to simulate high protein products. This research took rice protein as testing objects, used melamine, urea and ammonium sulfate as disruptors by three protein determination methods: Lowry, CBB methods, Kjeldahl method and studied different disruptors on three kinds of protein content determination methods. These results showed that the melamine amount was less than 300 g/kg, had no obvious interference effect on the determination results,keeping within 3% error; The content of urea at less than 100 g/kg had no obvious interference effect on the determination results. With addition continuing to increase, the CBB and Lowry measuring data had a certain degree of decline, and the CBB method performance was more obvious; Ammonium sulfate's influence on the determination of protein content was the weakest. The protein determination results showed a trend of decline when adding amount was more than 50 g/kg. These conclusions showed that compared with Kjeldahl method and CBB method, Lowry method was more weakest. but different kinds of proteins had different types and proportions of amino acids, so the most suitable method to every protein for determination should not be treated as the same. The best method should be chosen according to the specific circumstances to achieve the best results.
Rice protein is a kind of high-quality protein. However, there is a serious adulteration phenomenon in the current dairy products and food raw materials. In order to reduce production costs, some companies and businesses add non-protein nitrogen material to rice products to simulate high protein products. This research took rice protein as testing objects, used melamine, urea and ammonium sulfate as disruptors by three protein determination methods: Lowry, CBB methods, Kjeldahl method and studied different disruptors on three kinds of protein content determination methods. These results showed that the melamine amount was less than 300 g/kg, had no obvious interference effect on the determination results,keeping within 3% error; The content of urea at less than 100 g/kg had no obvious interference effect on the determination results. With addition continuing to increase, the CBB and Lowry measuring data had a certain degree of decline, and the CBB method performance was more obvious; Ammonium sulfate's influence on the determination of protein content was the weakest. The protein determination results showed a trend of decline when adding amount was more than 50 g/kg. These conclusions showed that compared with Kjeldahl method and CBB method, Lowry method was more weakest. but different kinds of proteins had different types and proportions of amino acids, so the most suitable method to every protein for determination should not be treated as the same. The best method should be chosen according to the specific circumstances to achieve the best results.
引文
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[7]唐玉莲,易凯,史外鹏等.广东紫珠总黄酮提取工艺优化及含量测定[J].怀化学院学报,2014,33(5):6-9.
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[10]Lowry OH,Rosebrough NJ,Farr AL,et al.Protein measurement with the Folin phenol reagent[J].The Journal of Biological Chemistry,1951,193(1):265-275.
[11]Pierce J,Suelter C H.An evaluation of the Coomassie brilliant blue G-250 dye-binding method for quantitative protein determination[J].Analytical Biochemistry,1977,81(2):478-80.
[12]王爱军,王凤山,王友联等.低浓度蛋白质含量测定方法的研究[J].中国生化药物杂志,2003,24(2):78-80.
[13]魏群.基础生物化学实验[M](第3版),北京:高等教育出版社,2009.
[14]赵书景.粮食、饲料中蛋白质含量测定方法的研究[D].扬州大学硕士论文,2008.
[15]王文高,陈正行,姚惠源.不同蛋白酶提取大米蛋白质的研究[J].粮食与饲料工业,2002,25(2):41-42.
[16]欧卫华.浅谈《生物化学》课程的导入语设计[J].读与写杂志,2010,7(11):83.
[17]王章存,刘卫东,申瑞玲等.大米蛋白的酶水解机制研究——Ⅱ酶水解过程中蛋白质的组分变化[J].中国粮油学报,2007,22(4):5-8.
[18]张莉,李海生.劳力氏(Lowry)法测定蛋白质肽类含量的最佳样品量的考察[J].天津药学,2000,12(2):74-76.
[19]赵世光,张焱,薛正莲等.酶-碱法提取碎米蛋白工艺研究[J].食品工业科技,2012,33(11):256-259.
[2]陈智慧,史梅,王秋香等.用凯氏定氮法测定食品中的蛋白质含量[J].新疆畜牧业,2008,24(5):22-24.
[3]姬勇,陈霞,罗力力.全自动定氮仪测定大米中蛋白质含量的测量不确定度分析[J].农产品加工,2011,10(1):78-79.
[4]李宁.几种蛋白质测定方法的比较[J].山西农业大学学报:自然科学版,2006,26(2):132-134.
[5]肖文同.揭开饲料添加剂的神秘面纱[J].中国动物检疫,2012,29(6):30-32.
[6]吕晓锋,罗希韬,崔静等.玉米芯水解制木糖过程中氨态氮类成分研究[J].中国食品添加剂,2014,25(5):119-124.
[7]唐玉莲,易凯,史外鹏等.广东紫珠总黄酮提取工艺优化及含量测定[J].怀化学院学报,2014,33(5):6-9.
[8]孙士青,王少杰,李秋顺等.考马斯亮蓝法快速测定乳品中蛋白质含量[J].山东科学,2011,24(6):53-55.
[9]Kuaye A Y.An ultraviolet speetrophotometric method to determine milk protein content alkaline medium[J].Food Chemistry,1994,49(2):207-211.
[10]Lowry OH,Rosebrough NJ,Farr AL,et al.Protein measurement with the Folin phenol reagent[J].The Journal of Biological Chemistry,1951,193(1):265-275.
[11]Pierce J,Suelter C H.An evaluation of the Coomassie brilliant blue G-250 dye-binding method for quantitative protein determination[J].Analytical Biochemistry,1977,81(2):478-80.
[12]王爱军,王凤山,王友联等.低浓度蛋白质含量测定方法的研究[J].中国生化药物杂志,2003,24(2):78-80.
[13]魏群.基础生物化学实验[M](第3版),北京:高等教育出版社,2009.
[14]赵书景.粮食、饲料中蛋白质含量测定方法的研究[D].扬州大学硕士论文,2008.
[15]王文高,陈正行,姚惠源.不同蛋白酶提取大米蛋白质的研究[J].粮食与饲料工业,2002,25(2):41-42.
[16]欧卫华.浅谈《生物化学》课程的导入语设计[J].读与写杂志,2010,7(11):83.
[17]王章存,刘卫东,申瑞玲等.大米蛋白的酶水解机制研究——Ⅱ酶水解过程中蛋白质的组分变化[J].中国粮油学报,2007,22(4):5-8.
[18]张莉,李海生.劳力氏(Lowry)法测定蛋白质肽类含量的最佳样品量的考察[J].天津药学,2000,12(2):74-76.
[19]赵世光,张焱,薛正莲等.酶-碱法提取碎米蛋白工艺研究[J].食品工业科技,2012,33(11):256-259.