Effect of spices on GABA synthesizing enzyme activity and lowering saltyness and investigation of salt signal transaction mechanism

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K00872
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Eating habits
• Research Institution: Ryukoku University
• Principal Investigator: Ueno Hiroshi 龍谷大学, 農学部, 教授 (30241160)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: GABA / 香辛料 / GAD / 塩味増強剤 / 減塩食品 / 味覚 / 対比効果

Outline of Final Research Achievements

Spice extracts activating glutamate decarboxylase (GAD67)are screened. Those extracts may express salt enhancing effect. Proteins associating with GAD67 in type III taste bud are searched by surface plasmon resonance method. We extended lists of spice extracts expressing GAD67 activation. Those spice extracts were subjected for the development of low salt diet foods. Some of the spice extracts were used to prepare low salt content bread that still maintains saltyness that be provided with original recepe. Protein-protein complex formed with GAD67 were screened and two proteins were identified. One of such protein was reported to associate with alpha-subunit of GABA-gated chloride ion channel protein complex; thus, it suggests chloride ion plays a central role in salt signal transaction in type III taste bud.

Free Research Field

生化学・応用微生物学・ビタミン学

Academic Significance and Societal Importance of the Research Achievements

香辛料には，独特の味覚を提供する以外に，酵素に働きかけてその活性を制御する機能を持つことを示してきた．そのなかで塩味受容体を発現しているIII型味蕾細胞内に発現が確認されているグルタミン酸デカルボキシラーゼ（GAD67）の活性制御がある．GAD67を活性化する香辛料抽出物には塩味増強効果がみられ，減塩効果が認められる．調理学には少量の塩で，甘味やうま味を増強する効果（対比効果）が知られているが，香辛料の塩味増強効果は，この対比効果に関与し，減塩しても香辛料成分の存在でうま味を維持できることになる．そこで，減塩パンなどに適用することで，香辛料成分の減塩効果を示し，今後の減塩食につながると考える．