12 - Beers

Abstract

Beer is one of the most popular alcoholic beverages around the world. It has a very long history, even beyond the record of civilization. Yeast, malt, hops, and water are the main ingredients for beer brewing. Sometimes, other starch adjuncts like rice and syrup are also used as the brewing materials. The brewing process contains several steps, including mashing, fermentation, filtration, and filling. Hops are indispensable in beer, as they supply beer with flavor compounds, antibacterial ability, and health effects. Amylases (α-amylase, β-amylase, α-1,4-glucan glucohydrolase, and deramifying enzyme) and proteases are two main enzymes used in beer brewing. Yeast is the soul of beer brewing, as it plays a decisive role in beer quality. Based on the yeast used in the brewing, the most recognized categories of beer are ale and lager. Because the color, foam, and taste are the critical features that affect the quality of beer, white and smooth foam not only gives drinkers a pleasant feeling and excellent flavor, but also avoids the loss of flavor and direct oxidation. Compounds like CO2, metal ions, proteins, and flavor substances in beer have positive impacts, whereas lipids and alcohols have negative impacts on formation and stabilization of beer foam. Among these compounds, protein Z was the first protein found in beer and has the character of stabilizing beer foam. Moreover, saccharides, as the most abundant material in beer other than water, not only can maintain the nonbiological stability of beer, but also play a very important role in maintaining foam stability. Finally, stability is always the goal for beer brewers, and it is usually referred to as biological stability, nonbiological stability, foam stability, and flavor stability.