Publications by authors named "Koichiro Koie"

Background: Flavor hops (Humulus lupulus L.) are recognized as key raw materials that impart unique flavors to beer, especially in the emerging craft-beer industry. In this study the sensory evaluation of hop cone aromas using hop water extract by boiling (HWEB) was applied to develop new flavor hop cultivars in a screening from tens of varieties and breeding lines.

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Article Synopsis
  • Recent breeding has led to new hop varieties with distinct aromas, known as "flavor hops."
  • This study looked at the effects of harvesting hops at various stages (DAF 45, 65, 75, and 85) on specific volatile compounds.
  • Results showed that while some compounds remained steady or decreased, the compound 3-sulfanyl-4-methylpentan-1-ol (3S4MP) significantly increased with later harvests, suggesting that harvest timing can be used to enhance this flavor compound in hops.
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  • - A new method was developed to measure six specific thiols in hops and beer without using organic mercury compounds, involving silver ion solid phase extraction and gas chromatography-tandem mass spectrometry.
  • - The method showed good linearity and recovery rates (74-100% for hops and 79-113% for beer), with low limits of detection for the thiols below their odor thresholds in beer.
  • - Among the measured thiols, 4-methyl-4-sulfanylpentan-2-one (4MSP) and 3-sulfanyl-4-methylpentan-1-ol (3S4MP) are particularly significant for contributing to the flavor of different hop varieties in beers. *
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It is well-known that various beers contain many flavor compounds derived from barley malts, hops, yeast fermentation, and other raw materials. Among these flavor compounds, terpenoids are mainly derived from hops. Linalool, one of the monoterpene alcohols, has been found in various beers and been regarded as an important factor for a hop-derived beer flavor.

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