An estimated 4 per cent of adults and 8 per cent of children in the EU - the total population tops 380 million - suffer from food allergies, according to the European Federation of Allergy and Airways Diseases Patients' Associations.
And a small slice of these have a reaction to fruit, commonly in the form of the 'oral allergy syndrome'. This mostly affects the mouth area, with prickling and a swelling of the lips, throat and tongue after eating the fruit.
Food makers looking to obliterate allergen concerns from their food formulations and looking for an allergen-free label will be drawn towards ingredients, such as the allergen-free apple, that remove all risk.
For his thesis at Wageningen University, Zhongshan Gao identified and localised genes which are involved in the allergenicity of apples.
It has previously been proven that apple allergy is caused by one or more proteins in apple, the so-called Mal d1- till Mal d4-proteins). Mal d1 is the most important allergen in apple.
Gao's thesis explains that the exact identification of the genes involved in allergenicity is a major challenge for two reasons. Firstly, more allergens can play a role together. Secondly, patients differ from each other in their sensitivity to these allergens and their varieties.
The research aimed to trace and characterise the genes which are decisive for the amino acid compound of the four most important allergenic protein types.
In addition, the project set out to develop genetic markers for predicting, at the seedling stage, whether or not an apple contains allergenic proteins.
Gao identified 26 genes, 18 of which coded for the Mal d1 protein. This allergen is especially relevant to patients in North West Europe, who also suffer from hay fever in the spring as a reaction to birch pollen.
His research showed that the Mal d 1 genes lie on three chromosomes, with the genes on chromosome 16 playing a clear role in the allergenicity.
Furthermore, it appeared that the amount of Mal d1 protein was less important than the amino acid composition. Until now, medical studies have primarily focused on the quantity, reports Gao.
Partially because of the results of this study and the use of modern technologies such as marker assisted breeding and reduction in gene activity, the future may bring new 'less-allergenic' apple varieties onto the market targeted at allergic consumers.
"The results can also be used for genetic research in other fruit crops such as pear and peach, which contain similar allergens," reports the scientist.
Gao's thesis was part of the EU-SAFE project, a large European interdisciplinary consortium. Subsequent studies will take place as part of the EU project ISAFRUIT, within which apple allergy and the making and selection of hypoallergenic fruits will form a significant part.
Keeping a pace with the rise in allergies, new legislation brought into the EU at the end of 2004 and to be enforced in November this year, imposes considerable legal requirements to curb the risk for food allergy sufferers.
Directive 2003/89/EC, amending Directive 2000/13, essentially means food makers must flag up on the food label possible allergen ingredients and their derivatives: cereals containing gluten, fish, crustaceans, egg, peanut, soy, milk and dairy products including lactose, nuts, celery, mustard, sesame seed, and sulphites.