2018 Fiscal Year Final Research Report
Elucidation of generation mechanism and sensory properties of oligosaccharides in sake
Project/Area Number |
17K15274
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Research Category |
Grant-in-Aid for Young Scientists (B)
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Allocation Type | Multi-year Fund |
Research Field |
Food science
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Research Institution | Tokyo University of Agriculture |
Principal Investigator |
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Project Period (FY) |
2017-04-01 – 2019-03-31
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Keywords | オリゴ糖 / 清酒 / メタボロミクス / 糖転移 / 官能評価 / α-グルコシダーゼ / 配糖体 |
Outline of Final Research Achievements |
Analytical method for separation and detection of oligosaccharides in sake was established and a variety of isomer of oligosaccharides in sake was found by the method. The structure of a part of isomers with degree of polymerization (DP) 6, 7 and 8 were determined as novel oligosaccharides. Among those, oligosaccharide with DP6 showed resistant to glucoamylase digestion, probably due to the branched structure at non-reducing end. The sensory properties of the oligosaccharides in sake (>DP2) were evaluated and the importance for sake quality was shown, even though the estimated detection threshold was higher than the average amount in sake. Gene disruption experiment revealed that a major alpha-glucosidase, AgdA, plays a role in digestion of isomaltose and kojibiose, and generation of isomaltotriose and several glycosides in sake-brewing. We also identified two novel maltoside, which may influence on the quality of sake because the amount reaches 0.15% in same commercial sake.
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Free Research Field |
農芸化学
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Academic Significance and Societal Importance of the Research Achievements |
糖類は清酒中に最も多い不揮発性成分であるにもかかわらず、グルコースと2糖類以外は構造や呈味性などについては全く分かっていなかった。本研究により清酒中オリゴ糖は構造が多様であり、清酒の香味に一定の寄与をしていることが示された。また一部オリゴ糖が、これまで報告のない独特の分岐構造を持つ難消化性のオリゴ糖であることが明らかとなった。さらに新しい機能性物質としての有望な、既知の機能性物質と類似した新規化合物を見出した。以上は清酒品質向上や高付加価値化に資する成果であることに加え、特徴的構造のオリゴ糖の発見は、複雑な清酒製造工程における微生物酵素の働きを反映していると考えられ学術的にも興味深い。
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