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.

OMNIS Sample Robot S, OMNIS Dosing Module and OMNIS Advanced Titrator equipped with dProfitrode and dAg-Titrode for the determination of chloride content.
Figure 1. OMNIS Sample Robot S, OMNIS Dosing Module and OMNIS Advanced Titrator equipped with dProfitrode and dAg-Titrode for the determination of chloride content.

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.

Table 1. Mean chloride content of two meat products determined with an automated OMNIS system (n = 6).
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
Figure 2. Example titration curve of the chloride determination of chicken breast.

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.

Author

Metrohm USA

9250 Camden Field Pkwy
33578 Riverview, FL

Contact