Excellent flavor for use in acidic food and drink, astringency, bitterness is reduced, to obtain the acid-soluble soybean protein material. In gel filtration using (pH7.0) 1 wt% SDS containing buffer is detected at 220nm, the content of the fraction of the mass number 150kDa or more than 18%, TCA 45% is (0.22M) solubilization rate the following, I use the acid-soluble soybean protein material. In addition, in the production of acid-soluble soybean protein material to perform the acidic heat treatment in excess of 100 ℃ and phytase treatment, by starting a protease treatment at pH3.4 or less, and acid-soluble soybean protein material having the characteristic I can be produced. [Selection] Figure Figure 1酸性飲食物に用いるための、渋味,苦味が低減され風味に優れた、酸性可溶大豆たん白素材を得る。1重量%SDS含有緩衝液(pH7.0)を用いたゲル濾過において、220nmで検出される、質量数150kDa以上の画分の含量が18%以下、TCA(0.22M)可溶化率が45%以下の、酸性可溶大豆たん白素材を用いる。また、フィターゼ処理および100℃を超える酸性加熱処理を行う酸性可溶大豆たん白素材の製造において、pH3.4以下でプロテアーゼ処理を開始することで、該特性を持った酸性可溶大豆たん白素材を製造できる。【選択図】図1
