果蔬饮料中检测方案(自动电位滴定)

多样品自动进样器测定果蔬饮料中总酸含量 应用资料水果饮料中含有柠檬酸、苹果酸和其他有机酸。总酸度表示这些有机酸的含量。在水果饮料中，总酸与糖含量的比例对其偏好和风味有显著影响。因此，为了生产质量一致的饮料，控制总酸是非常重要的。本应用说明描述了测量水果饮料(柑橘)总酸的例子。请注意，这些测量是使用多样品自动进样器进行的。多个样品的烧杯被放置在一个转盘上，这样就可以自动进行连续的测量。在这个测试中，测量是通过参数设置进行的，检测到pH为8.2作为终点。京都電子工業株式会社KYOTO ELECTRONICSMANUFACTURING CO.，LTD.APAT-0147en APAT-0147en Application Note Measuring the acidity of fruit beverages using a multiplesample changer Industry Food & beverage Instrument Automatic potentiometric titrator Measurement method Potentiometric titration / Neutralization titration Standards GB/T 12456 1. Scope Fruit beverages contain citric acid， malic acid， and other organic acids. The acidity indicates theamount of these organic acids. In fruit beverages， the ratio of acidity to sugar content has asignificant effect on the preference and flavor. Accordingly， it is very important to control theacidity in order to manufacture beverages of consistent quality. This Application Note describes an example of the measurement of the acidity of a fruit beverage(from mandarin oranges). Note that the measurements were performed using a multiple samplechanger. Multiple beakers containin1g名 the samples were placed on a turntable， enablingconsecutive measurements to be performed automatically. In this test， the measurements wereperformed with the parameter settings configured so that a pH of 8.2 was detected as the end point 2. Post-measurement procedure To suppress efflux and enrichment of the electrolyte when storing the electrodes， seal theelectrolyte filling port in the combined glass electrode with a rubber stopper. The performance of the combined glass electrode quickly deteriorates if it is stored while dry. Thefollowing storage methods are recommended. ·Short-term storage (less than one month)： Store in pure water. ·Long-term storage (one month or longer)： Store in a mixture of pH4 standard solution and 3.3mol/L potassium chloride solution in a 1：1 volume ratio. 3. Apparatus ·Automatic potentiometric titrator (preamplifier STD) ·Multiple sample changer ·Combined glass electrode (Electrolyte： 3.3 mol/L potassium chloride solution) ·TTemperature compensated electrode 4. Reagents Titration liquid 0.1 mol/L sodium hydroxide solution OthersStandard solutions at a pH of 7 and 9 京都电子工业株式会社-可睦电子(上海)商贸有限公司电话： 021-54488867 电邮： kemu-kem@163.com 上海市徐汇区宜山路333号1201室网址： http：//www.kem-china.com 5. Procedure 1) Calibrate the combined glass electrode using the standard solutions at pH 7 and 9. 2) Introduce the sample into a beaker and weigh it. 3) Using a measuring cylinder， add 100 mL of pure water， and place the beaker in the multiplesample changer. 4) Titrate with a 0.1 mol/L sodium hydroxide solution， with a pH of 8.2 as the end point. 6. Calculation Acidity (%)*=(EP1-BL1)×TF×6.404×0.1/S EP1 Titration volume (mL) BL1 Titration volume (mL) for a blank test=0 TFTitration liquid factor=0.9920 S Amount of sample introduced (g) * Calculated as the mass percent concentration of citric acid 7.Example —Titration parameter— Auto Int. Level Stop Number of EP 1st End Level 8.2 pH Gain Max Volume 20(mL) Data Sampling Auto Channel/Unit(Ctrl.) Ch1，pH Ctrl. Speed Standard Channel/Unit(Ref.) Off Other Control Standard pH Polarity Standard Auto Int. Mode Standard Titr. Type Check No Check Stirrer Speed 4 Direction Auto Wait Time 0(s) Dose Mode None Shower 15s Drain 30s (The above condition is an example. The setting condition depends on the model.) 京都电子工业株式会社-可睦电子(上海)商贸有限公司电话： 021-54488867 电邮： kemu-kem@163.com Table 1 Measurement result Sample (g) Titration amount (mL) Acidity (%) 1 10.1474 9.9927 0.626 2 10.0642 9.9089 0.625 3 10.2621 10.0971 0.625 4 10.1302 9.9625 0.625 5 10.5239 10.3445 0.624 6 10.1199 9.9523 0.625 7 10.4572 10.2788 0.624 8 10.2777 10.1057 0.625 9 10.7381 10.5577 0.625 10 10.1543 9.9836 0.625 Mean 一 一 0.625 SD 一 一 0.0004 RSD(%) 一 一 0.065 8. Summary Acidity measurements were performed using an automatic potentiometric titrator. In this test， amultiple sample changer was used to perform a consecutive series of measurements automatically.Using a multiple sample changer makes it possible to reduce the labor required for themeasurements and improve efficiency. 京都电子工业株式会社-可睦电子(上海)商贸有限公司电话：021-54488867 电邮： kemu-kem@163.com 都電子工業株式会社KYOTO ELECTRONICSMANUFACTURING CO.，LTD.