New strategy for targeting beta-glucan activity and breeding of malting barley

大麦(大麦)是制麦和酿造的关键原料。麦芽由发芽的大麦制成，用于酿造酒精饮料。酿造公司是大麦麦芽的主要消费者。加拿大是全球29亿美元麦芽贸易业的主要参与者之一。大麦麦芽品质是一个重要的经济表型，代表着一个复杂的、多组分的性状。β-葡聚糖(BG)是决定酿造潜力和酿造产量的主要因素。BG影响麦汁在酿造过程中的胚乳变形和粘度，造成很大的酸败和过滤困难。为了最大限度地减少麦汁中的β-葡聚糖分子，正在不断努力鉴定具有葡聚糖酶活性的酶/蛋白质。我们已经成功地鉴定出一种新的大麦蛋白TLP8(Thaumatin Like Protein)，它能与β-葡聚糖结合，并在制麦过程中显著降低其含量。我们的发现表明，较高数量的HvTLP8蛋白可以最大限度地减少啤酒过滤过程中遇到的问题。HvTLP8的葡聚糖酶型活性在缓解啤酒酿造过程中的β-葡聚糖分子问题和辅助改良啤酒大麦品种方面具有很大的潜力。这可作为麦芽品种后代选育的功能生化标记。

Barley (Hordeum vulgare) is a key ingredient in malting and brewing. Malt, produced from germinating barley is used for making alcoholic beverages. Brewing companies are the main consumers for barley malt. Canada is one of the major players in 2.9 billion USD global malt trading industry. Malting quality of barley, an economically important phenotype, represents a complex, multi-component trait. Beta-glucan (BG) is a major factor determining malting potential and brewing yield. BG affects the endosperm modifications and the viscosity of wort during brewing which cause great lautering and filtration difficulties. Continuous efforts are being made to identify enzyme/proteins with glucanase activity with the aim to minimise beta -glucan molecules in wort. We have successfully identified a novel barley protein, TLP8 (thaumatin like protein), which binds to beta-glucan and significantly lowers its amount during malting process. Our findings suggest that higher amounts of HvTLP8 protein can minimize problems encountered during the beer lautering and filtration processes. Glucanase type activity of HvTLP8 has great potential to mitigate problems of beta-glucan molecules during malting and brewing process and assist the development of improved malting barley varieties. This could be used as functional and biochemical marker for the breeding of future generation of malting varieties.