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目的根据国标GB/T5009.86-2003中第二法,建立2,4-二硝基苯肼法测定果汁中维生素C的各条件,测定不同预处理后柚汁中维生素C含量,并对进行分析。方法经预处理(直接榨汁、沸水加热、果胶酶反应等)过的果汁样经活性炭处理,被氧化为脱氢抗坏血酸,再与2,4-二硝基苯肼作用生成脎,于500nm波长测定吸光值。结果抗坏血酸标准溶液在范围2~10ug/m L时,线性关系良好,相关系数为0.999。结论直接榨汁总Vc含量最高,商场果汁产品Vc含量略低于实验室直接榨汁。
Objective According to the second method of national standard GB / T5009.86-2003, the conditions of 2,4-dinitrophenylhydrazine determination of vitamin C in fruit juice were established, and the contents of vitamin C in different grades of pre-treated grapefruit juice were determined. analysis. Methods After pretreatment (direct juice extraction, boiling water heating, pectinase reaction, etc.), the juice samples were treated with activated carbon, oxidized to dehydroascorbic acid, and then reacted with 2,4-dinitrophenylhydrazine Wavelength Determination of absorbance. Results Ascorbic acid standard solution showed a good linearity in the range of 2 ~ 10 ug / mL with a correlation coefficient of 0.999. Conclusion The total Vc content of direct juicing is the highest, while the Vc content of juices is slightly lower than that of laboratory direct juicing.