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 α subunit of β-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 frac-tion. 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 enzy-matic digestion. Among the three major allergens, the α subunit of β-conglycinin and Gly m Bd 2 8K 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 alter-natively by an enzymatic digestion. By the application of these procedures, several hypoal-lergenic soybean products, such as cooked soybean grains, soybean curd (Tofu), and fer-mented soybean paste (Miso), soymilk, and a jelly-like soybean cake have been made to eval-uate their usefulness by a challenge test for soybean-sensitive patients. It has been demon-strated by a preliminary trial that about 80% of the soybean-sensitive patients could ingest these hypoallegenic products without any adverse reactions.