IF you do purchase a wine yeast, of whatever sort, it will usually be supplied in only a small quantity and will have to be "activated" for use. All this means is that you start it working, and therefore multiplying, so as to build up a much larger number of active yeast cells for introduction to the must. The principle is the same in most cases.
Instead of adding the wine yeast direct to the must, one starts it off in a specially-prepared bottle of sterilised fruit juice of some sort, and nutrient, and then, when the contents of the "starter bottle" are fermenting vigorously, they are added to the must. The yeast thus has a much better chance of succeeding, since it is already in full activity.
The snag, of course, is that one has to remember to activate the yeast in this way about 48 hours before it is likely to be needed, to allow time for this starter fermentation to get under way. Once a yeast has been activated, this problem diminishes, for a little of it can always be kept back and "grown on" in another starter bottle by adding more fruit juice, water, sugar and nutrient, and the process can be repeated ad infinitum as long as care is taken to keep the yeast under sterile conditions.
One can buy yeast cultures either in test-tubes (sufficient for one or two gallons) or in bottles, for from five to ten gallons.
For the starter juice, one can use either the juice from which the wine is to be made (if some can be obtained beforehand), or some other fruit juice. Since you need half a pint of it the flavour of your wine will not be affected materially if you use a different juice from that of the bulk. To this add an ounce of sugar.
Another good starter is: a tablespoonful of pure malt extract, a tablespoonful of granulated sugar, the juice of a lemon, and half a pint of water.
Whichever you use, bring it to the boil in an aluminium or sound enamel saucepan to sterilise it, and then allow it to cool.
To activate a tube culture first sterilise a small bottle by boiling it in water for five minutes. Then allow it to cool, plugging it with cotton-wool. Stand the tube culture in warm, NOT boiling or really hot, water for a few minutes to loosen the agar or jelly-like slide which bears the yeast culture, and then, with a knitting needle which has been dipped in boiling water, slide the agar, and with it the yeast, into the bottle. Then pour in the prepared starter juice, plug the neck of the bottle with cotton-wool, and stand in a temperature of about 70 deg. F. After about two or three days the starter bottle will be in full ferment and tiny bubbles will be seen rising to the surface. It can then be added to the main bulk of the liquor.
The bottle culture is a little handier, for the juice, prepared as above, has merely to be poured into the yeast bottle, and the cotton-wool plug replaced. After 24 hours in a warm place (about 70 deg. F.) fermentation will be under way and after a few days there will be enough active yeast to start off 5-10 gallons of must.
If you wish to use the starter bottle at intervals over a period make a starter from four ounces of orange and two ounces of lemon juice (preferably strained), plus four ounces of water and one ounce of sugar. When the yeast has been added and it is fermenting three-quarters of it can be used to activate a brew, and the remaining quarter can be topped up with juice made in the same way and will after a week or so also be fermenting and ready for use.
Wine yeast is also sold in tablet and in liquid form, but must still be activated in the same way before use. Individual suppliers send detailed instructions with their yeasts, so there is no need to worry; you will find it quite simple.
Baker's yeast, brewer's yeast, or granulated yeast (the packeted variety) can be added direct to the liquor. Baker's yeast should be fresh. It is best added when the temperature of the liquor is lukewarm, about 70 deg. F. These will give you a more vigorous and frothy ferment than a wine yeast; this does not help the wine, but it perhaps does help someone who is just starting winemaking and who wants to be sure that a ferment really has got going.
In all the recipes in this book use a wine yeast where possible or, failing that, 1 level teaspoonful of a good granulated yeast per 1 gallon of liquor, or H oz, baker's or brewer's yeast.
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