Soybean allergens and hypoallergenic soybean products.

Abstract

About 15 soybean proteins were shown to be recognized by sera of soybean-sensitive patients with atopic dermatitis. Three of them were identified as major allergens and designated as Gly m Bd 60K, Gly m Bd 30K, and Gly m Bd 28K, respectively. Gly m Bd 60K is an alpha subunit of beta-conglycinin well known as a major soybean storage protein. Gly m Bd 30K is also known as a soybean oil-body-associated glycoprotein with a molecular weight of 34,000, which is homologous to Der p (or f) 1, a major allergen of house dust mite, classified under the papain super family. Gly m Bd 28K is a vicilin-like glycoprotein with a molecular weight of 26,000, a minor component fractionated into 7S globulin fraction. The reduction of allergenicity of soybean and soybean products has been developed with respect to the above-mentioned major three allergens as the targets by the use of the combined techniques of a chemical breeding, a physico-chemical treatment, and an enzymatic digestion. Among the three major allergens, the alpha subunit of beta-conglycinin and Gly m Bd 28K were eliminated from soybean seeds by the development of a mutant line, Tohoku 124, introduced by a chemical breeding technique. The strongest allergen, Gly m Bd 30K, was almost completely removed from defatted soymilk prepared from Tohoku 124 by a salting-out technique and a centrifugation under the limited pH and ionic strength and alternatively by an enzymatic digestion. By the application of these procedures, several hypoallergenic soybean products, such as cooked soybean grains, soybean curd (Tofu), and fermented soybean paste (Miso), soymilk, and a jelly-like soybean cake have been made to evaluate their usefulness by a challenge test for soybean-sensitive patients. It has been demonstrated by a preliminary trial that about 80% of the soybean-sensitive patients could ingest these hypoallegenic products without any adverse reactions.