Main Beer Brewing Ingredients
- Malt
- Hops
- Sugar
- Yeast
- Water
Other Ingredients
Yeast
To make good beer it is essential to use a genuine beer yeast. Only
beer yeasts give a true beer flavour and settle well in the bottle to
form a firm deposit from which it is possible to pour clear sparkling
beer.
Other yeasts, such as bakers' yeast, produce 'off', sometimes bad
flavours and do not settle well, thus producing a cloudy unattractive
beer.
Yeast is a single celled living organism. Technically, it is a mould.
When we place yeast cells into the wort, they begin to multiply and
grow. In doing this, they feed on the sugar which they convert to
alcohol and carbon dioxide. This process is called fermentation. When
the yeast has consumed all of the sugar, fermentation ceases and we can
bottle the beer.
Although it is a living organism, yeast can be prepared in a dried
form and it is quite stable provided it is not subjected to extremes of
temperature. Dried yeasts are the most convenient to use in home
brewing. The powder or granules are sprinkled into the
wort. A number of
excellent types can be purchased in packets. If you do not use the whole
packet in a brew, the packet should be resealed and stored in a cool dry
place.
Two types of yeast are used in beer making; top fermenting yeast and
bottom fermenting yeast.
Since top fermenting yeast needs oxygen to work, it is the type to
use with open fermenters such as plastic garbage cans.
When using top fermenting yeasts, some time after fermentation
commences, the top of the brew becomes covered with a frothy, creamy
layer. This must be skimmed off, otherwise the yeast cells in it (lie
and sink back into the beer and decompose. The result is a beer with a
foul bitter flavour, somewhat like the smell of burning plastic. A beer
to which this has happened is said to be 'yeast bitten'. Because of the
flavour, some home brewers wrongly attribute this trouble to the plastic
of their garbage can fermenters.
Top fermenting yeasts work best at temperatures between 60°F and
70°F, but will tolerate temperatures outside this range.
Ale yeasts are top fermenting yeasts.
Bottom fermenting yeasts work best in the absence of oxygen and are
the yeasts to use with a closed fermenter. As the name indicates, they
work at the bottom of the brew and skimming is unnecessary.
Lager yeasts are bottom fermenting yeasts.
Bottom fermenting yeasts will continue to work at much lower
temperatures than top fermenting yeasts, down to about 40°F.
Bottom fermenting yeasts can be used in an open
fermenter and work quite
well. However, the beer should be bottled as soon as possible after
fermentation is complete, otherwise, oxygen contamination can result in
the beer going sour. An important point to remember. The lid should not
be taken off the open fermenter more often than is necessary to observe
the progress of fermentation.
On the market, there is at least one brand of dried all purpose beer
yeast, which acts as a bottom fermenter in a closed container, or a top
fermenter in an open container. With either method, it gives excellent
results.
Some home brewers claim they can taste a difference in beer made with
either a top or a bottom fermenting yeast. Personally, I am not
convinced that there is much difference. The choice is often made for us
by what yeast is available. Where a choice does exist, it is a simple
matter to try them out and see which yeast gives you the best result.
When starting another brew immediately after bottling the last one,
instead of using fresh yeast, about a half-cupful of sediment from the
previous brew can be used. If you are careful about cleanliness, this
can be repeated six to eight times. After that, it would be advisable to
start with fresh yeast. Also, the sediment can be kept for a week or
more, stored in a clean sterilized jar in a cold, but not freezing, part
of the refrigerator. It should be discarded It any trace of a sour smell
develops.
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