Chemical analysis of condensed tannins in barley and malt

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Brewing is an important industry for the Canadian economy, with small batch craft breweries in particular aregrowing rapidly within this sector. Beer is brewed with malted barley, and thus contains many barley-derivedplant chemicals. Of primary importance among these are the tannins, a mixture of oligomeric and polymericpolyphenols which impact both beer flavour and stability. Tannins can interact with proteins and many otherbiomolecules, and are also known for their positive effects on human health. Under some conditions, tanninsprecipitate proteins and can cause the generation of 'cold haze' in beer. This is a major concern to brewers as itleads consumers to question the quality of the product. Cold haze can be removed prior to bottling usingchemical methods or filtration, but for the craft beer industry, alternative approaches are preferred. Therefore, along-term goal of malsters and brewers is precise control of barley tannin within malt. Our previous workindicated that significant changes occur in tannins during the kilning step of malt production: the concentrationof the water-soluble tannin fraction increases steeply, while other tannin fractions decrease or remain the same.These changes are likely to be important to the tannin content of beer; to date, nothing is known about thenature of the water-soluble tannins, for example, if they are composed of larger or smaller oligomeric tannins.The proposed research will therefore focus on the chemical analysis of the soluble tannin fractions. This will bedone at key stages of the malting process in order to understand tannin dynamics, and also with specialty maltskilned under different conditions. Non-tannin components, and in particular phenolic acids, will also bemeasured. We will make use of our recently purchased analytical system, a ultra-high pressure liquidchromatography (UHPLC) system, that will allow us to simultaneously measure compounds by UV absorptionand mass spectrometry. Ultimately, we aim to determine if the release of water-soluble tannins is mediated byenzymatic processes, and if these can be manipulated during malting in order to control tannin content of malt.This would help control cold haze formation, and represent a major advance for craft brewers.