Fermentation.
In brewing, fermentation is the conversion of sugar into carbon dioxide gas (CO2) and ethyl alcohol. Enzymes within a yeast cell carry out this process. It is in fact a complex series of conversions that bring about the conversion of sugar to CO2 and alcohol. Yeast is a member of the plant family and in brewing we use the sugar fungi form of yeast. These cell gain energy from the break down of the sugar. The by-product, CO2, bubbles through the liquid and dissipates into the air. The alcohol remains in the liquid which is great for us but not for the yeast, as the yeast dies when the alcohol exceeds its tolerance level. Brewer's yeast tolerate up to about 5% alcohol. Beyond this alcohol level the yeast cannot continue fermentation. Wine yeast on the other hand tolerates up to about 12% alcohol. The level of alcohol tolerance by yeast varies from 5% to about 21% depending on yeast strain.
The fermentation process has other limits such as temperature. Greater than 27C kills the yeast less and than 15C results in yeast activity which is too slow. The amount of sugar in the solution can be too much and this can prevent fermentation.
Main ingredients.
Malted barely –Is the major source of sugars, which are fermented by the yeast in the later stages of the process.
Water – provides the liquid medium essential for the fermentation process. The bulk of beer is water and, as we shall see, water type and quality is essential to the flavour of the final beer.
Yeast – is the key component in brewing, carrying out the fermentation reaction in which enzymes are used to change sugar to alcohol.
Hops – provides the characteristic bitterness and contribute to the aroma of the beer.
Ingredients/materials used.
Beaker 250ml
Sugar 100 g
Water 100ml
Brewers yeast
Method - School/home brew.
Making the malts.
The malts are already made and ready to use.
Beer making.
- Get all of the equipment and set it up.
- Get about 2 pounds of sugar and put it into water. The more sugar you put in the stronger the alcohol becomes. (40 pints of water in total).
Malts hops, sugar
- Put the malts into the water and mix well.
- Add brewers (yeast), which is in powder form into the mixture.
- Keep the mixture warm for about 3-4 days. (To keep warm use a small heater).
- If you want to bottle the alcohol add a bit more sugar, which would be a second fermentation and then leave the alcohol in the bottle for about 14 days so that it can settle and become clear. Putting the sugar into the alcohol will give it more flavour.
Equation = glucose + yeast ethanol + CO2
Method – industry.
Making the malts.
- Cereal grains (usually barley) is wetted and allowed to sprout.
- The grain is then gently heated in the kiln to halt germination.
Beer process.
- The malt barley is ground to a coarse flour – the grist.
- The grist is mixed with hot water; the enzymes are reactivated and break down the carbohydrates and proteins to simple sugars and amino acids (yeast food). The extracted liquid (sweet wort) containing sugars is drawn off. The spent grains are sold as animal feed.
- The sweet wort is boiled with hops to form a bitter, hopped wort.the spent hops are sold as fertilizer.
- Yeast is added to ferment the hopped wort.
- Casks are filled with beer (which contains a small amount of yeast). Sugar and finings are added. The beer is chilled, filtered and carbon dioxide is added.
- The beer is pasteurised to prevent spoilage by microorganisms, and filled into kegs. Cans and bottles are filled prior to pasteurisation.
Comparison – similarities/differences.
Industry.
There is one good reason why industry keep their products pasteurised is because it will give the product a longer shelf life.
School.
The one good reason for school brewery is that the beer can be produced in a short amount of time because the mixtures are ready mixed.
Strengths/weaknesses.
Industry - Strengths.
Fresh yeast is used for better taste.
The brewery process in industry can be sold.
Lots of beer can be made at the same time with the same flavour.
Yeast that is left over can be sold separately.
Can be pasteurised for longer lasting taste.
Industry – weaknesses.
One thing that would go wrong during the process would affect the brew like bacteria, which is attracted to the ingredients used in the brewing. They can cause problems during fermentation. The results would be that the fine beer would become a sour and cloudy, undrinkable liquid.
School – strengths.
Ready-made wort would make it easier to make.
It would save a lot of time to make the beer.
Kit form
School – weaknesses.
The wort that is used is not fresh and that you would get a different taste.
Cannot be sold as a product.
If bacteria get into the alcohol it would taste like vinegar.
It would take along time for the alcohol to settle and clear
Evaluation.
In industry people are making beer in thousands and thousands of barrels a day. Which is done completely by machines so that there would be no errors.
In home brewing you have to be very careful on the count that it brewing has to be watched everyday in case something went wrong like the beer getting a disease on the count that the beer was exposed to bacteria in the air. You would have to realise the health and safety hazards to make sure nothing goes wrong, and that you don’t get harmed.
