Studies on distribution of protein and allergen in graded flours prepared from whole buckwheat grains

Buckwheat (Fagopyrum esculentum Moench) is one of the traditional crops and has become a renewed target of interest or a popular crop as a healthy foodstuff, because it is a good source of cereal protein which is rich with essential amino acids. However, what is critical to our health is that buckwheat contains proteins which cause a hypersensitive reaction (allergy). In this study, to decrease the allergenic activity of buckwheat products, some graded flours were prepared from various portions of buckwheat grain, and its protein distribution and characteristics of each graded flour fractions were determined. The protein and ash contents of all buckwheat fractions increased in the order from the inner fraction to the outer fraction. From SDS–PAGE patterns, the concentrations of 15, 22, 35, 39 and 50 kDa proteins of the inner fractions were lower, and there were clear differences in the protein compositions between the inner and outer buckwheat flour fractions. Detection of allergenic proteins by IgE-immunoblotting showed that sera pooled from 9 patients reacted with proteins of 15 and 22 kDa bands, named Fag e 2 and Fag e 1, respectively. IgE binding activities of proteins, Fag e 1 or Fag e 2 of the inner fractions were weaker than those of the outer fractions. Therefore, the inner fractions without major allergic proteins could be separated from whole buckwheat grains, and also expected to be applied to manufacturing processed foods with low allergen. Furthermore, the graded-milling procedure could be used to provide less-allergenic buckwheat flours.