- The name beer is given to non-distilled alcoholic beverages are made from partially germinated cereal grains, known as malt.
- They include ales, lagers and stouts, which normally contain 3–8% (v/v) ethanol.
- The other main ingredients are hops (giving beer a characteristic aroma and flavour), yeast and water.
The brewing process is mainly divided into four main stages:-
- Mashing and wort preparation
- Yeast fermentation
- Malting is the partial germination of cereal grain for six–nine days to make a malt.
- This is the first beer ingredient and contains mainly starch, some protein and hydrolytic enzymes.
- Malted barley is predominantly used, however beers are also made with malted wheat, occasionally malted oats and even malted sorghum.
Mashing and wort preparation:
- Mashing and wort preparation includes the production of the aqueous fermentation medium, otherwise
called as wort.
- It contains fermentable amino acids, sugars and other nutrients, and is prepared by solubilizing malt components through the action of endogenous hydrolytic enzymes.
- In most countries, a proportion of adjuncts are now also added, which are unmalted cereal and non-cereal starch sources, and sugar syrups.
- The resulting liquid wort is then ‘sterilized’ by boiling; at the same time hops are added to impart their bitter flavour and characteristic aroma.
- Overall, wort preparation takes approximately 5–8 hr.
- Yeast fermentation is a non-aseptic batch process that uses a starter culture of a selected brewing strain of S. cerevisiae.
- The inoculated wort undergoes an alcoholic fermentation to produce ethanol, CO2 and minor
metabolites that contribute to flavour and aroma.
- Fermentations usually last for two to seven days depending upon the type of beer being produced.
- Post-fermentation treatments are conducted to mature or condition the new beer to make it ready for consumption, which may take from one to several weeks.
- The raw materials, excluding hops, the preparation of the wort and the yeast fermentation, are essentially the same for the production of both whisky and malt vinegar.
- However, the major objectives are somewhat different. For whisky and vinegar production, the main aim is to maximize alcohol production prior to the respective steps of distillation and acetification.
- In beer brewing, ethanol production by itself is rather less crucial, as development of sound flavour profile and other quality factors is equally important.
- Traditionally, all necessary enzyme activities for the process were provided by the malt, which generates the wort, along with yeast enzymes, that convert wort components to ethanol, CO2 and flavour compounds.
- However, commercial enzymes are now employed when raw materials are enzyme deficient, or to produce novel products, or act as aids in processing and in product stabilization.