ABSTRACT
Beer is a fermented alcoholic beverage and it is a typical example of old biotechnology. The raw materials used in the brewing process are water, malt, hop, and yeast. Actually enzymes, fruits, and other unmalted cereals such as corn, rice, or wheat can be used in beer production. However, yeast has a central role in the brewing process, metabolizing sugars of wort into ethanol, carbon dioxide, and several aroma compounds, including esters, higher alcohols, aldehydes, and organic acids. Most beers are brewed with the use of a single yeast strain: Saccharomyces cerevisiae (top yeast) and Saccharomyces pastorianus (bottom-yeasts) for ale beer and lager beer, respectively. Special beers such as the Belgian lambic beers or American coolship ale (ACA) are obtained from the spontaneous fermentation of Saccharomyces and Brettanomyces yeasts, with the contribution of lactic acid bacteria and acetic acid bacteria. The use of non-Saccharomyces yeast has been poorly investigated in the brewing industry. Nowadays, different non-conventional yeasts are under investigation in the brewing process to improve bioflavor of beer.
This chapter will describe the raw materials and all steps of brewing process focusing the attention on the new fermentation strategies to enhance the aroma profile, diversify the final product, and improve complexity of beer flavor.
