In the US alone, an estimated 1.5 million people suffer from nut allergies. But now food engineers have discovered that the maturation, curing and roasting of peanuts increases their allergen content, so by tweaking these processes the nut industry may be able to make them safer.
Unfortunately, many of the proteins and sugars blamed for allergies are thought to give roasted peanuts their distinctive, rich flavour. "It will be a trade-off," says Si-Yin Chung, head of the team that discovered the link between processing and allergy at the US Department of Agriculture's Southern Regional Research Center in New Orleans, Louisiana.
Three processes give roasted peanuts their special flavour. The first, maturation, simply involves leaving the peanuts to ripen in the field. "Immature peanuts taste bad," says Chung. In the second- curing- the nuts are dehydrated by warming them to between 35 and 70°C. Finally, they are roasted at around 160 °C for about 20 minutes.
At each of these stages, the researchers exposed the nuts to antibodies from people with peanut allergies. The more antibodies that bind, the more allergens are present, giving Chung a way to rate the nuts' "allergenicity". He found that each process creates additional compounds called advanced glycation end adducts- pairings between proteins and carbohydrates that are thought to be more allergenic than either alone. The results will be published in the Journal of Agricultural and Food Chemistry.
Many of these substances enrich flavour, so getting rid of them could destroy the taste. But Chung is hopeful that modifications to processing could minimise the allergenicity of roasted peanuts while keeping most of the taste. Curing below 60 °C, for example, doesn't generate new allergens.
Author: Andy Coghlan
US contact - Michelle Soucy, New Scientist Boston Office:
Tel: 1-617-558-4939 or email michelle.soucy@newscientist.com
New Scientist issue: 28th June 2003
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