ALTERNATIVE METHODS FOR SO2 DETERMINATION

One of the biggest trends in recent years has been the move towards nutrition that is both healthy and sustainable. As a result, it is not just modern consumers who have become more and more aware of nutritional information and ingredients in food: the body of regulation by official institutes and agencies for additives and preservatives is also growing all the time.

This white paper deals with the preservative sulphur dioxide (SO2) and how to determine this substance in foodstuffs. SO2 is present – generally in gaseous form or dissolved in water – in many day-to-day foods such as dried fruit, wine, potato dishes and seafood.

Although SO2 has classic antimicrobial properties, it also has a toxic effect, and so in the EU it must be labelled when it is found in concentrations of 10 mg/kg or higher.

For food producers, this involves a delicate balancing act: on the one hand, they need to comply with the specified limit values, but at the same time, the SO2 content has to be high enough to achieve its full effect. It is therefore very important to have an analysis method that is both as precise as possible and also efficient – both for consumers and for manufacturers.

The optimised Monier-Williams method (oMW) is defined as the reference method for checking the SO2 concentration in foodstuffs by the Association of Official Analytical Collaboration (AOAC) 990.283, in DIN EN 1988-14, and in Article 64 of the German Food and Feed Code (LFGB5). However, this method is time-consuming and labour-intensive, requiring more than two hours for each measurement, which is especially problematic for laboratories with a high sample throughput. There is therefore a strong demand in practice for alternative methods that provide equivalent results.

In our white paper, we present two alternative methods for and compare them against the reference method.

Reference Method:

Alkalimetric method for samples without other volatile acids - Method based on DIN EN 1988-1: 1998-05 and AOAC 990.28