Yeasts, or barms, are of many varieties, but I purpose here to deal
with only two kinds--that commonly known as German yeast, which is
mostly used in England, and Parisian barm, the kind most in use in
Scotland.
A great point in working German yeast is to know when it is in proper
condition, as it is very liable to go bad in very warm weather, or if
kept in a very warm place. Care should be taken to keep it in a place
as near a temperature of 56° to 60° Fahr. as possible. Should there be
any suspicion that the yeast is not up to the mark, a simple and sure
test is to get a clean cup or tumbler, half fill it with warm water of
a temperature of 100°, put an ounce of loaf sugar in the water, and
when dissolved add one ounce of yeast. The yeast will, of course, sink
to the bottom, but if it is sound and in good condition it will rise to
the top in two minutes. Should it take much longer than that, the less
you have to do with it the better.
Parisian barm makes a nice showy loaf, but for flavour I prefer German
yeast. To make Parisian barm 1 gallon of water is put into a pan at,
say, 140° Fahr.; weigh 2 lbs. of crushed malt, put it into the water
at the above temperature, cover it up for about three hours; one hour
before you are going to make your barm, that is two hours since you
put your malt to steep, put 3 gallons of water into a large pan, put
it on the fire; when it boils, add 2 oz. of good fresh hops, well boil
for twenty minutes; after which well strain the malt through a hair
sieve. Put it into the barm tub and add as much flour as can be nicely
stirred in with the barm-stick. Then put the boiling hop-water through
a sieve on top of the malt water and flour and well stir it. It should
be properly scalded. Some put the hops in a small linen bag made for
the purpose and put it in the boiling water, squeezing it against the
side of the pot before taking it out. Supposing it to be five o’clock
in the afternoon, it may be put by with a couple of sacks over it till
five o’clock next morning. Then “set the barm away” (as they say in
Scotland), by adding to the above liquid half a gallon of the barm
previously made.
After the old barm is added to the new, in a few hours a scum gathers
on the top. This scum will either start at the side of the tub and work
gradually to the other side, or I have seen it start in the middle and
work itself slowly to the sides of the tub. When ready it should have a
nice clear bell top. It takes from ten to twelve hours to work before
it is ready.
By following this method one may always have good barm. Cleanliness
is very essential for barm, and care should be taken that neither
grease nor churned milk shall get near it. We need scarcely say that
experience is required in this as in other things.