This Metrohm Application Note H–123 describes the determination of the total sodium content in instant noodles which are also called «two minute noodles» in some countries.
Worth its salt
In the presence of an excess of potassium and fl uoride ions, sodium reacts exothermically with aluminum to produce NaK2AlF6 (elpasolite). This reaction is the cornerstone of a new method for determining sodium in foodstuffs using thermometric titration. Not only is it rapid, straightforward, and reliable, but the method can also be automated which makes it ideal for routine checks – even within the process itself.
Instant noodles: Precise analysis of sodium content required
These products contain considerable amounts of sodium (at least 50% of the recommended daily dosage), which means that precise analysis of the sodium content is required.
Absorbing large quantities of sodium in the diet – through table salt, for example – can have a negative impact on health. Numerous jurisdictions have responded to this issue by ruling that food packaging must specify sodium content.
Argentometric titration of the chloride content (assuming that the sodium content in the noodles originates exclusively from the sodium chloride that is added to them) is unsuitable for precise analysis, as the nutrient contents listed on the product packaging document the presence of additional sodium salts other than sodium chloride.
Sodium ion reacts exothermically with aluminium ions in the presence of potassium and fluoride ions to form insoluble NaK AlF («elpasolite»). Aluminium must be in 3+ 26 the Al ionic form.
The reaction may be used for the quantitative determination of total sodium in various foodstuffs. A necessary precondition for accurate analysis is that all sodium must be released for the food matrix. In the case of foods with a high protein content, trichloroacetic acid CCl3COOH («TCA») has been found to be suitable in denaturing the protein and assisting in complete liberation of the sodium. In this case, the noodles are made with high protein wheat flour.
Thermometric titration is an ideal choice for routine determination of sodium in all kinds of foods.
Download the Metrohm Application Note H-123 and the White Paper “Worth its salt” to learn more!