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The investigation was designed to study whether DHA in fish oil encapsulated in porous starch granules coated with water-insoluble corn protein, zein, can be utilized during passage through the gastrointestinal tract in rats. The in vitro digestion trial showed that zein used for coating starch granules was decomposed by proteolytic enzymes. After feeding porous starch granules containing fish oil, coconut oil, or corn oil for 3 weeks, serum triglycerides and phospholipids were significantly lower in the rats on fish oil than in the other rats. The proportion of DHA in total fatty acid of the fish oil group was significantly higher in both liver and brain lipids than in the other two groups. These results clearly show that fish oil encapsulated in porous starch granules coated with zein could be digested and absorbed. Moreover, it was confirmed that the granules had been changed morphologically by scanning electron microscopic analysis of the contents of the alimentary sections, showing that the film of zein had been digested in stomach and small intestine. The digestibility of fish oil in the capsules was shown to be 96.8%.

食品由来のタンパク質消化産物から, 食品の三次機能である生体機能を担う物質を検索する目的で, ゼイン, ダイズタンパク質, カゼイン, オボアルブミンをペプシンにて消化し, 消化物のクロロホルム/メタノール抽出画分についてカルモデュリン依存性環状ヌクレオチドホスホジエステラーゼ (PDE I) に対する影響について検討した。ゼインのペプシン消化産物はCa2+/カルモデュリン存在下にPDE Iを低濃度で阻害し, 他のタンパク質から得られた消化産物より4～8倍の強力な阻害活性を示した。そこで, ゼインから得られた画分をODSカラムを用いて精製したところ, PDE Iに対する阻害作用がIC50が53μg/mlと非常に阻害活性の強い画分が得られた。この画分をODSカラムでさらに精製し, 得られた画分のアミノ酸の一次構造の解析を行ったところ, AGILPLSPLFなる構造を示すデカペプチドであることが判明した。