THE CHEMISTRY OF TASTE
BY PETER WATTS • PHOTO COURTESY OF CMBTC
Former British Prime Minister Winston Churchill once quipped, “Most people hate the taste of beer to begin with. It is, however, a prejudice.”
Over the past two decades, the global brewing industry witnessed significant diversification in beer styles. Driven by rapid growth in the craft brewing sector, sophistication of consumer tastes and product awareness, this evolution has spurred interest among maltsters and brewers in the sensory attributes of malt and the varietals that make up malt blends.
Brewers have long been acutely aware of the sensory attributes of barley varieties. Major brewers employ strict controls on the approval of new barley varieties. To pass the taste test, a pure varietal malt must be brewed without processing issues or sensory defects.
Exactly how barley contributes to the flavour of beer is not well understood. Beer contains hundreds of chemical compounds. Each of these alone or in combination may impact flavour and aroma.
To determine which compounds are responsible for taste characteristics would allow new barley varieties to be screened for these chemical components. This would assist in maintaining the attractive flavour profile of Canadian malting barley and would benefit the barley value chain through increased global competitiveness.
In 2018, with funding from Agriculture and Agri-Food Canada’s Science Cluster and additional contributions from the provincial barley associations, the Canadian Malting Barley Technical Centre (CMBTC) set out to identify compounds within malting barley that may contribute positively to flavour attributes in malt and beer.
For two seasons, Canadian barley varieties AAC Connect, CDC Bow, CDC Copeland and Harrington were grown at Lacombe, Saskatoon, SK, and Brandon, MB. Though each area has unique soil and climate conditions, all received the same agronomic management.
Using an identical recipe, CMBTC conducted brewing trials on harvested barley samples with the use of its pilot malting systems. Malt, wort and beer samples were analyzed according to American Society of Brewing Chemists methods. Volatile organic compounds found were also analyzed by gas chromatography-mass spectrometry. As well, nuclear magnetic resonance spectroscopy identified the presence of 45 non-volatile compounds in the wort and beer. Numerous of these contribute to flavour and aroma and varied in concentration by statistically significant amounts between varieties and growing location.
Nine sensory attributes of the beer were then evaluated by trained panellists. These qualities included graininess, maltiness, sweetness, bitterness and astringency, as well as the presence of compounds such as isoamyl acetate, which has a banana-like flavour. The study also analyzed the final beer product for performance attributes such as degree of fermentation, colour, sugar composition, ethanol content and more.
While the study’s findings suggest variety and growing location can affect beer quality and flavour, eight of the nine sensory attributes were not significantly affected by genetics or environment. CDC Bow and Harrington were most closely aligned, while CDC Copeland had higher levels of dimethyl sulfide (which has a canned corn-like aroma), maltiness and astringency. The lone significant exception, acetaldehyde (which has a green apple-like taste) levels for beer brewed with CDC Copeland were significantly higher than beer brewed with Harrington.
In other words, the results suggest despite flavour differences among the beer samples, these would generally not be detectable by consumers.
Peter Watts is the CMBTC managing director.