A recent study has brought new insights into the role of linalool, a crucial element in determining the scent of beer. Contrary to long-held beliefs, the study found a much smaller difference in the odor threshold of linalool’s two forms, providing fresh understanding of how beer’s scent evolves through brewing and storage.
Linalool, known for its floral and citrusy scent, is a significant component derived from hops, impacting both beer’s aroma and extending its shelf life while contributing to its bitterness.
Led by the Leibniz Institute for Food Systems Biology at the Technical University of Munich, researchers have now overturned an assumption about linalool that stood for nearly two decades. Their findings deepen our knowledge of how beer’s aroma profile changes with brewing and aging.
Hops and beer contain two forms of linalool, known as enantiomers (R)- and (S)-linalool, identical in atomic composition and connectivity but differing in spatial structure, akin to an object and its mirror image. This small yet vital difference affects their odor intensities.
During brewing and storage, beer’s aroma transforms as some (R)-linalool in hops changes to (S)-linalool. It was previously believed, based on a 1999 study, that the (R)-form’s odor threshold was significantly lower (about 80 times) than the (S)-form, implying a greater influence on beer’s aroma. However, this lacked solid data.
Closing this knowledge gap, the research team, led by brewing technologist Klaas Reglitz and food chemist Martin Steinhaus from the Leibniz Institute, improved a method to isolate pure (S)-linalool. Collaborating with the Research Center Weihenstephan for Brewing and Food Quality, they achieved the first isolation of enantiomerically pure (S)-linalool.
With sufficient quantities of pure (S)-linalool, the team could accurately determine the specific odor thresholds of both linalool forms in water and unhopped beer, using a trained sensory panel. Their findings showed that in water, the thresholds for (R)- and (S)-linalool were 0.82 and 8.3 micrograms per kilogram, respectively. In unhopped beer, these values were 6.5 micrograms per kilogram for (R)-linalool and 53 micrograms per kilogram for (S)-linalool.
The research indicates that the previously believed influence of (R)-linalool on beer’s aroma was overestimated. “Although (R)-linalool has a higher odor potency, the difference between the two enantiomers is not as drastic as once thought, being only about eight to ten times,” explains Martin Steinhaus. Klaas Reglitz adds, “The transformation from (R)- to (S)-linalool during storage doesn’t impact the beer aroma as significantly as previously believed. Our study enhances understanding of aroma changes during storage.”
For further details, refer to the study “Enantiospecific determination of the odour threshold concentrations of (R)- and (S)-linalool in water and beer” by K. Reglitz et al., published in July 2023, in Brewing Science.
Frequently Asked Questions (FAQs) about Beer Aroma Research
What does the new study reveal about linalool in beer?
The study uncovers that the odor threshold difference between the enantiomers of linalool (R)- and (S)-linalool is significantly less than previously thought. This new insight is pivotal in understanding the development of beer’s aroma during brewing and storage.
How does linalool affect beer’s aroma?
Linalool, a hop-derived ingredient, is known for its floral and citrusy fragrance. It plays a crucial role in shaping beer’s aroma, in addition to enhancing its shelf life and contributing to its bitterness.
What was the previous assumption about linalool in beer, and how has it changed?
Previously, it was assumed that the odor threshold concentration of (R)-linalool is about 80 times lower than that of (S)-linalool, suggesting a stronger influence on beer aroma. The new study, however, shows that this difference is only about eight to tenfold.
What was the key achievement of the research team from the Leibniz Institute?
The team, led by Klaas Reglitz and Martin Steinhaus, successfully isolated enantiomerically pure (S)-linalool for the first time. This breakthrough enabled them to determine the specific odor thresholds of both linalool variants in beer.
How does the new finding impact the understanding of beer’s aroma during storage?
The study indicates that the conversion of (R)- to (S)-linalool during beer storage does not have as significant an impact on the aroma as previously believed. This contributes to a more nuanced understanding of how beer’s aroma changes over time.
More about Beer Aroma Research
- Understanding Linalool’s Role in Beer Aroma
- The Impact of Hops on Beer’s Shelf Life and Taste
- Uncovering the Mysteries of Beer’s Scent
- Advances in Brewing Science: The Leibniz Institute’s Study
- Linalool Enantiomers: A Comparative Study
- Sensory Analysis in Beer Research
- The Evolution of Beer Aroma During Brewing and Storage
- Breakthrough in Isolating Pure (S)-Linalool