Testing finds widespread cassava starch adulteration in China

Researchers in China have developed a quick and accurate way to spot adulteration of starch products with cassava, which is an increasingly common form of food fraud.

The team reports in the journal PLOS One that the low cost of cassava means it is often substituted for or added to higher priced starches such as potato and wheat, defrauding consumers and also raising the risk of unexpected allergic reactions.

Using a molecular biology technique known as droplet digital polymerase chain reaction (ddPCR), the scientists discovered that 30 per cent of sweet potato, 25 per cent of corn and 40 per cent of potato starch samples were adulterated with cassava.

The paper reveals once again that food fraud isn’t only an issue with pricy foods, with even relatively low-cost staples vulnerable as fraudsters pursue a profit margin.

Current techniques such as physical and chemical analysis are “time-consuming and labour-intensive and cannot measure the extent of adulteration,” which can help distinguish between accidental and intentional adulteration, write the authors.

If only small (3 to 4 per cent) proportions of cassava starch are found it could be an artifact, for example from use of the same equipment to process different starch products. At higher levels, say 10 to 30 per cent, it points to deliberate, economic-motivated adulteration.

The ddPCR approach detects DNA in the sample, and was found to predict accurately how much starch was present in the sample by weight, with no cross-reactivity with other starches tested like sesame, walnut, soybean and hazelnut.

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