肉制品中的氯化物
AN-T-004
2020-05
zh
Fully automated sample preparation and analysis based on ISO 1841-2
为了保证产品质量，须对肉制品中的氯化钠含量进行监控，因为不能超过相关公共卫生机构规定的限值。食品中的氯含量与盐含量相关，因此各种规范和标准都对其测定方法进行了说明。为了减少工作量和工作时间，本应用报告介绍了根据 ISO 1841-2 标准用硝酸银对肉制品中的氯化物进行全自动电位滴定的方法，包括使用 Polytron 匀浆器进行全自动样品制备。
In order to maintain product quality, the sodium chloride content in meat products must be monitored, as the limit values defined by the respective public health authorities must not be exceeded. The chloride content in food correlates with the salt content; its determination is therefore described in various norms and standards. However, preparation of meat samples is time consuming, as it requires homogenization with a mixer and a chloride extraction with water.
In order to reduce workload and increase sample throughput, this Application Note describes a fully automatic potentiometric titration of chloride with silver nitrate in meat products based on ISO 1841-2, including fully automated sample preparation using a Polytron homogenizer.
The method is demonstrated for different meat products: pork sausage «Lyoner» and chicken breast with curry crust. If necessary, the spice crust around the meat is removed and then the sample is cut into small pieces.
This analysis is carried out on an automated system consisting of an OMNIS Advanced Titrator and an OMNIS Sample Robot S equipped with a dProfitrode and a dAg-Titrode. Furthermore, a Polytron homogenizer is used for sample preparation.
Water is added to a reasonable and representative amount of sample. The pH is adjusted with nitric acid to below pH 1.5. The sample is titrated with standardized silver nitrate until after the equivalence point is reached. For dip rinsing of electrodes and burets, first water, then isopropanol is used. Afterwards, the electrodes are conditioned in water for one minute before the next sample.
The analysis demonstrates acceptable results and well-defined titration curves. The results and an example titration curve are displayed in Table 1 and Figure 2, respectively.
| Sample | Chloride content in mg/100 g sample | SD(rel) in % |
|---|---|---|
| Pork sausage «Lyoner» | 1175.5 | 1.1 |
| Chicken breast with curry crust | 1158.1 | 0.8 |
Titration is a precise and reliable method to determine the chloride content in meat products according to international standards, such as ISO 1841-2.
Using an OMNIS Sample Robot equipped with a Polytron homogenizer allows a fully automated sample preparation and chloride content determination of up to four samples in parallel, increasing accuracy and freeing up valuable time of the operator and thus increasing the productivity in the lab. The OMNIS system offers the opportunity to customize the system according to your needs, and expand it for other required titration applications on foodstuff.
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Internal reference: AW TI CH1-1264-112018