A new sensory training for modern IPA beer styles
A large challenge in the discourse around yeast and hop interactions is communicating the sensory impacts of individual compounds. For example, why should brewers be interested in creating more ‘tropical’ free thiols, such as 3SH, during fermentation if they don’t know what this thiol smells and tastes like?
To address this challenge, we are developing a Biotransformation and Hop Compounds training using Siebel Sensory Kits. This training aims to provide a unique lexicon-building experience that differs from the typical focus on off-flavors found in other sensory kits. Instead, it will offer a series of six samples that allow brewers to smell and taste six common fruity compounds in beer that can be influenced by yeast and hop selection. This sensory training is now in the final stages of development. From here, it will go to the global team of Lallemand Brewing Technical Sales Managers to get your feedback. Interested? Get in touch with your local Lallemand rep and see what they are planning!
Helping brewers identify biotransformation compounds
It is the complex interplay between many hop and yeast-derived sensory compounds that provides the overall impression of fruitiness (and other characters!) in hoppy beers. By communicating the sensory characteristics of specific flavor-active compounds, we hope to give brewers the tools to tailor recipes and brewing processes to maximize the desired sensory profile. Within this training, we explore terpene alcohols, thiols, esters, and lactones. There is some narrative in the brewing context for some of these selections in the kit.
A sneak peek: Identifying biotransformation sensory compounds
The training starts with the terpene alcohol geraniol. This compound is perceived as sweet, floral, and fruity. Its presence may lower the sensory thresholds of other aromatic compounds such as tropical fruit thiols, thereby allowing greater aromatic expression of these compounds at lower concentrations. Geraniol can be contributed from some hop varieties in a sensory-active ‘free’ form or increased by yeast interaction with sensory-inactive ‘bound’ geraniol.
The second terpene alcohol is citronellol, which is typically only present in f inished beer due to yeast biotransformation of geraniol. Citronellol skews towards a more citrusy/lemongrass sensory profile and is converted from geraniol at yeast strain-dependant rates.
Next is a thiol compound, 3-sulfanylhexanol (3SH), which is commonly described as tropical fruit, white wine, or grapefruit-like in character. As with geraniol, this compound can be found in ‘free’ form in some hop varieties, while some yeast strains are able to release more ‘free’ from the ‘bound’ pool contributed by some hop varieties.
The Siebel Institute Sensory Kits are liquid vials that allow simple and precise beer spiking for in-house training (Photo: Siebel Institute)
Following this is the yeast-esterified form of the previous compound, 3-sulfanylhexanol acetate (3SHA), which shows potent guava and passionfruit characters.
The penultimate compound is a hop-derived ester, 2-methylbutyl isobutyrate (2MIB), which can be perceived as apple, pear, and stonefruitlike in beer. This is higher in some hop varieties and is able to be transesterified by yeast into a wider range of fruity compounds.
The final compound is a lactone, gamma-nonalactone, which is one of a family of compounds that can be present in ingredients such as hops and malt but can also be created by yeast. This family of compounds is present elsewhere in nature in oak barrels, coconut, and ripe stonefruit. We are working to elucidate how yeast metabolism influences these stonefruit aromas, and a better understanding of these pathways will help brewers enhance these aromas in their beers.
In summary, this novel sensory training will give brewers a more scientific basis by which to pick apart hop and yeast flavours and aromas in their hoppy beers, and the information to build these into recipe creation for achieving targeted sensory outcomes.
Visit our Sensory Corner on the Siebel Institute website
This article originally appeared in the Lallemend Brewing Newsletter, 12.12.2024
