VITICULTURE.

New Zealand Journal of Agriculture, Volume XVIII, Issue 4, 21 April 1919, Page 233

VITICULTURE.

By

S. F. ANDERSON,

Vine and Wine Instructor.

WINE-MAKING HINTS.

The stage of wine-making embracing the crushing and vatting of the grapes will now be over. It is during this period and the subsequent rackings and separation from the lees and other matter that the good keeping and general excellence of the wine is affected. The bulk of lees in wines made from grapes of low sugar-content is just as great as

that in wines made from grapes containing a high percentage of sugar, but the amount of alcohol developed is less. The lower the alcohol the shorter should be the time between making the wine and clearing it of lees.

Red Wine. The grapes for red wine are fermented with their skins in vats, so as to obtain the colour. As soon as fermentation is quite over, or apparently so, the wine should be drawn'off and put into the casks prepared to receive it. The marc is then pressed and the wine from this kept separate, as it requires more time to clear than that drawn off the unpressed portion. It may prove too harshhigher in tannin and —to mix with the other. The first wine when drawn off has possibly not quite cooled, and after being placed in the casks a further fermentation goes on. Bubblers are placed in the bung-hole of these casks, or a small bag of well-washed sand laid on the bung-hole. This is to permit the escape of the carbonic gas and prevent the air getting to the wine. When the wine is quite still it should have its first racking. The wine will not be quite clear, but the sooner it is taken off the thick lees the better. This occurs from two weeks to a month after the wine has been put into the casks. Other rackings at intervals of two or three months follow, till the wine is finally clear of yeast and other germs. Bright, clear, cool weather should be always selected for this work.

■ White Wine. — The methods followed in making wine from white grapes differ from those with the black. The must from the former is not usually fermented in the open vat. Immediately after being crushed and pressed the must is put into vats to allow of it' being aerated and skimmed. This is to eliminate the germs of fungus, yeast, and albuminous substances and impurities which by agitation come to the surface. The white grapes grown in New Zealand appear to require this process chiefly on account of their being low in natural sugar. Delicate light wines are greatly improved by this treatment. Their keeping-qualities are prolonged, and the finings will be more successful. This treatment takes up most of a day. The must is then put into hogsheads not later than the evening of the day when the pressing is done. The barrels are filled within a few inches of the bung-hole, in order to leave the necessary space , for expansion, this being produced by fermentation, which rapidly sets up. The foam or yeast issues from the cask and runs over, clearing the wine of impurities. While this is going on the overflow should be frequently wiped away from the sides of the cask, and washed from the floor of the fermenting-shed at least once in. the day. The whole place at this time teems with harmful bacteria, and any surface wet with must or wine offers a . favourable propagating-ground, especially during warm weather. The further management of the white wine is much the same as for the red.

General.— The wine should be preserved from contact with the air. All the alcoholic liquids are susceptible of undergoing acetic fermentation on coming in contact with air, water, and ferment. According to Pasteur, the acidity is due to a special ferment Mycoderma aceti. Wines of a low alcoholic strength are more susceptible to change than those of a greater strength. All casks containing wine should be kept filled. To do this it is necessary to have small casks and kegs, so . as to keep a supply for filling up. For general cellar-work there should

be a good supply of turned plugs. Bungs are only used when casks are closed up for sending out. When the wine is ready for closing up and the plugs put in they should be sealed up with paraffin-wax. All bungs and plugs should be well washed or scalded before being used. Keep the fermenting-house and its surroundings perfectly clean. If the grape-skins and stems (generally called the marc) are not to be used for distillation they should be taken right away at once for manure, as they soon become sour and breed the vinegar-fly.