Peanut corner

On peanut processing

Leatherhead International, the food research group, is investigating the way that processing (heating, cooking etc) affects allergens as, although researchers know a lot about the allergens themselves, they know relatively little about how processing affects them.

For example, it is known that the allergenicity of peanuts is enhanced by roasting at high temperatures but reduced by boiling, whereas the allergenicity of hazelnuts is reduced by roasting. But the processes are little understood.

The researchers hope to learn more about what happens to allergens during processing, paving the way to the development of potentially hypo-allergenic foods.

For further information check: or email Dr Clive Meredith, Principal research Scientist, Molecular Sciences at

Parasitic involvement

The June 2006 issue of New Scientist carried a lengthy investigation into peanut allergy that also looked at cooking methods pointing out that although the Chinese have a per capita consumption of peanuts which is almost as high as in the US (2 kg per head per annum) peanut allergy is almost unheard of in China. But in China peanuts are always either boiled or fried whereas in the US they are always roasted at very high temperatures.

Research in 2001 by Kirsten Beyer, now at the Charité Medical University of Berlin, found that boiling and frying can both reduce the amount of peanut allergen in a food and lower the affinity of the remaining allergens for IgE antibodies. Roasting, however, seems to increase the likelihood of an immune response by boosting the IgE’s binding strength.

West Africa suggests another possibility. Despite the fact that children in many West African countries are weaned on a boiled peanut mash, allergies are very rare.

But Africans - especially the rural poor - do have a healthy dose of parasites. Living with parasites appears to protect against the development of a range of allergies (New Scientist 16 Apr. 05 p34).

Maria Yazdanbakhsh at the University of Leiden in the Netherlands conducted a pilot study last year with 100 school children in Ghana where peanuts are a staple food.

The children all had loads of IgE for peanuts - but none of them had any signs of a peanut allergy. She has now returned to Ghana to study the children of both urban rich and rural poor as they have differing levels of exposure to all kinds of infection (parasitic, viral and microbial) and vary in the kinds and quantities of peanut products that they eat - from boiled to fried to roasted.


First published in October 2007

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