Beer Fermentation and its Details
Fermentation of beer is a very complex process. The products formed after fermentation are fermented product, alcohol, glycerol and acid. There are some different types of beer like Ale beer, Porter beer, Bock beer, Lager beer, Pilsner beer.
Composition of typical American beer
- Bland flavour
- pH – 4.3
- Alcohol content – 3 % to 5.8 %
- Sugar – 1.12 %
- Protein – 0.33 %
- Carbon dioxide – 2.2 %
Important points to be covered in manufacture of Beer
1 ] Raw Material Used – Raw material used for fermentation of beer is Malt. The green, dried, sprouted barley is called as malt.
2 ] Fermentation organism – Fermentation organism used here is yeast. The strain of Saccharomyces cerevisiae or Saccharomyces carlsbergensis is used in beer fermentation.
3 ] Fermentation Media – The media components used in fermentation should provide carbon, nitrogen and growth factors that are required for growth of yeast cells. The media components should provide colour, clarity and flavour to beer. It should also contribute foam formation and stability in fermentation.
Fermentation media used for manufacture of beer consist of the following components
- Malt adjunct
1 ] Malt – Malt id nothing but green, dried, sprouted barley. Malt is a source of protein, starch, growth factor and vitamins, Flavour and colour to beer. It also provides α , β amylase and proteolytic enzymes. This malt is dried grounded to powder and used in fermentation media.
2 ] Malt adjuncts – Malt adjunct is nothing but addition of starch to malt. These malt adjunct is added in the form of corn, rice, grids and flour. The source of starch is gelatinized and then added in the media.
3 ] Hops – Hops is a dried female flower of a hops plant. The hops flower gives aromatic and pungent character to the beer. It also provides α, β, γ resin and it provides preservative action and plays a important role in flavour development of beer.
Hops Flower Cone
4 ] Water – The best quality of water is used.The water of following composition is used
- Iron used in less than 1 ppm
- Sodium chloride in 200 to 300 ppm
- Calcium sulphate in 250 to 500 ppm
- Magnesium sulphate is used in trace amount.
- Calcium magnesium less than 10 ppm
- pH – 6.5 to 7
4 ] Mixing of Media components – The malt, malt adjuncts and water are mixed in proper amount and this mixture is kept for mashing. During mashing process the enzyme activity is carried out. After the enzyme activity is completed the liquid and solids are separated and the liquid is called as wort. This wort is added in a barrel and one fourth pound hops flowers are added. After addition of hops flower the barrel is boiled for extraction of hop components and inactivation of enzymes. This boiled wort is used as a fermentation media.
5 ] Fermentation procedure – The fermentation procedure is carried out in the following steps
The fermentation media is inoculated with 5 % of yeast innoculum at cold temperature that is 10° C to 11° C.This fermentation is carried out for about 9 days in the below given manner
- First 24 hours foam formation takes place.
- After 24 hours the wort is transferred in the second tank where all suspended particles are allowed to settle and clear wort is used for further fermentation procedure.
- During next 40 to 60 hours fermentation takes place vigorously and excess foam formation takes place and at this point the temperature rises to 12° C to 13° C. The fermentation is carried out at 12° C to 13° C for about 5 days.
- After 5 days the carbon dioxide evolution is seized and foam starts to collapse till next 24 hours that is till 7 days.
- The duration of 7 th day of fermentation to 9 th day of fermentation a yeast break down phenomenon take place. In this phenomenon the yeast cells form big follicles and settle down at the bottom of fermentor.
- The fermentation process is over and the fermented product obtained that is beer contains a harsh smell and turbidity. The beer obtained is further processed.
6] Processing of Beer – The Beer is processed in two steps
a] Clarification and Maturation – Clarification and maturation is carried out at cold temperature of about 0 °C to 3° C. Here during this process the ester formation takes place and flavour develops in beer. Here resin, yeast cells, precipitation of nitrogen takes places and beer gets clarified. Unstable proteins are removed by chill profiling. Antioxidants such as ascorbic acid or sulphur dioxide avoid oxidation of beer.
b] Carbonation – Incorporation of carbon dioxide in beer is carried out in the process of carbonation.
7 ] By products – The spent grains, sediments of filtration that is dried yeast are the byproducts of beer fermentation.
8 ] Packing of Beer – The carbonated and clarified beer is packed into bottles, barrels or cans and sold in the market.