sudan dye analysisIncreasingly, the global food supply chains have raised concerns about food safety. Products are grown and processed in widely differing environments under a variety of regulatory frameworks, travel thousands of miles, are kept in various storage conditions, experience temperature fluctuations that may affect shelf life, and are handled by many different people.

One of more visible stories in the news has been of adulteration of food products, whether it is melamine in milk and candy, carbohydrate fillers in food products, Sudan dyes in spices, or adulteration of expensive fruit juices with sugar. One only need look at the FDA food recalls or read Bill Marler’s blog on food recalls to learn adulterated food products are causing health problems and even death.

Here in this blog, we begin a multi-part series addressing the testing of adulterated food products.

The first question one might ask: Why the adulteration? The answer is that unscrupulous manufacturers cut costs by using cheaper (and sometimes dangerous) ingredients to increase profits.

We start here with Sudan dyes. These industrial dyes, typically used for coloring plastics solvents, waxes, oils stains, and lacquers, are showing up in spices, chili oil, and baked foods to improve the appearance of the food and, thus, command a higher price. Because Sudan dyes have been linked to increased cancer links, they have been banned in most countries. In fact, the International Agency for Research on Cancer (IARC) has categorized Sudan dyes as Class 3 carcinogens (link to monograph).

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UPDATE: March 28, 2012: A very interesting story (reported by the Asia Food Navigator site) has developed in India, where the Spices Board India (SBI) tested red chilli powder to be exported out of India and found 15 mg of Sudan Dye IV in every kilogram tested! It impounded the shipment of 14.7 metric tonnes and the exporter took the SBI to the Madras High Court challenging the validity of the impounding by the SBI. The High Court has supported food safety powers of the SBI in this contamination case.

The Chromatography applications lab at Thermo Fisher Scientific has developed a new, two-dimensional HPLC method described in Application Note 287, Two-Dimensional HPLC Combined with On-Line SPE for Determination of Sudan Dyes I–IV in Chili Oil, (downloadable PDF) with on-line, solid-phase extraction (SPE) inter column trapping for determination of Sudan dyes I, II, III, and IV in chili oil, a complex sample. The method reduces the labor required for the analysis of edible oil for Sudan dyes by eliminating the need for off-line sample preparation. Using the separation power of the first column to efficiently eliminate interferences, and using the second column to separate the analytes, the Thermo Scientific Dionex UltiMate 3000 ×2 Dual HPLC system provides an efficient platform for this method design, with detection limits exceeding the requirements of the EU and Great Britain.

Here is another example of identifying Sudan dyes in paprika using a diode array detector.

What are your food adulteration testing challenges?

Next Post: Determination of anthocyanins in pomegranate juice.