Chemical analysis of condensed tannins in barley and malt

酿酒是加拿大经济的一个重要产业，尤其是小批量精酿啤酒厂在这一领域发展迅速。啤酒是用麦芽酿造的，因此含有许多大麦衍生的植物化学物质。其中最重要的是单宁，它是一种低聚物和聚合多酚的混合物，影响啤酒的风味和稳定性。单宁酸可以与蛋白质和许多其他生物分子相互作用，也因其对人体健康的积极影响而闻名。在某些条件下，单宁会沉淀蛋白质，导致啤酒产生“冷雾”。这是酿酒商的一个主要担忧，因为它会导致消费者质疑产品的质量。冷雾可以在装瓶前用化学方法或过滤去除，但对于精酿啤酒行业来说，其他方法是首选。因此，酿酒师和酿酒师的长期目标是精确控制麦芽中的大麦单宁。我们之前的工作表明，在麦芽生产的烧制阶段，单宁发生了显著的变化：水溶性单宁部分的浓度急剧增加，而其他单宁部分的浓度下降或保持不变。这些变化可能对啤酒的单宁含量很重要；迄今为止，对水溶性单宁的性质一无所知，例如，它们是由较大还是较小的寡聚单宁组成的。因此，拟议的研究将集中在可溶性单宁组分的化学分析上。这将在酿造过程的关键阶段进行，以了解单宁动态，并在不同条件下使用专业麦芽技术。非单宁成分，特别是酚酸，也将被测量。我们将使用我们最近购买的分析系统，超高压液相色谱（UHPLC）系统，这将使我们能够同时通过紫外吸收和质谱法测量化合物。最终，我们的目标是确定水溶性单宁的释放是否通过酶促过程介导，以及是否可以在酿造过程中操纵这些过程以控制麦芽的单宁含量。这将有助于控制冷霾的形成，并代表着精酿啤酒的重大进步。

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.