The fermentation process

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Fermentation is a complete series of processes, controlled by enzymes, which are produced by the yeast cells themselves. Reference here is only to the process by which the yeast breaks down the sugar, and converts it into alcohol and carbon dioxide in almost equal proportions, together with a small quantity of bi-products. Fermentation should start as soon as possible once the ingredients are prepared, and for this reason it is advisable to prepare a starter bottle about 48 hours beforehand. If the yeast has already started working, the danger period for bacterial infection will have been kept to a minimum.

During the whole of the fermentation period, temperature is very important. The fermentation is in two parts. For the first 4–5 days after the yeast has been added to the must, there will be a vigorous foaming and the solids will be forced to the top. For this reason the must is usually kept in a covered bucket, and at an ideal temperature of 70°F/21°C. Once this heavy ferment has subsided, adhere strictly to a specific recipe. In most cases, it will be necessary to strain off the solids and place the liquor in a fermentation jar under airlock. This airlock should be approximately half-filled with water in order that all air is excluded. Carry out the transfer from bucket to jar carefully, avoiding as much contact with air as possible. At this stage the temperature may be reduced to 65°F/18°C, but the temperature should be constant throughout the remainder of the ferment if the best quality is to be obtained. This secondary ferment will continue, sometimes for several weeks, until such time as the yeast has built up the alcoholic content to (a) the stage when no sugar remains, in which case a dry wine has been produced, or (b) the stage when the strength of the alcohol has inhibited the yeast, which has died, and allowed the wine to stabilize, in which case the wine will probably be sweet.

From this, it can be seen that if a dry wine is required, the amount of sugar should be limited. For those who wish to have some control over the alcoholic content and the degree of sweetness, a hydrometer should be used.

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