The fermentation trap

The fermentation trap

IT is then that one needs to employ a fermentation trap. This is a simple device, being in

effect an air-lock, and we illustrate what is undoubtedly the most popular and commonly used

pattern, a glass U-tube with two bulbs.

This is inserted in the bung or cork of the fermenting vessel so as to be an airtight fit (this

is important, or the lock will not work), and a good tip is to use rubber bungs rather than corks to

ensure that there is no leakage. It is advisable to lightly grease the glass trap's stem and hold it in

a thick cloth when pushing it home, to avoid the risk of breakage and a hand badly cut by jagged

glass. The bottom of the glass stem must be above the level of the fermenting liquor; a half to

three-quarters of an inch is normally sufficient, as long as the liquor is not frothing so vigorously

as to force it out through the trap.

The U-bend of the trap is then filled with water, to the bottom of the bulbs, and in the

water is dissolved one eighth of a Campden tablet. Thus, even if a vinegar fly gets into the water,

and meets an untimely end, your wine will be safe, whereas if you have plain water in your trap it

will become infected with the bacteria from the dead fly. In that case, since the inner end of the

water is in aerial contact with your wine, it is still possible for your wine to be infected. So

always use this small quantity of sulphite in the bend of your traps, and renew it every month or

so. Alternatively, use in the trap glycerine of borax, which is less volatile and will not deteriorate.

Yet another method is to use plain water, but to plug the top of the trap with a tiny tuft of cotton

wool to deny the flies access.

The fermentation trap, incidentally, has a secondary purpose. The yeast, for the

reproductive process which it first employs, needs oxygen.

When, by means of the fermentation trap, we cut off its air supply, we force it to turn to a

secondary method of self-reproduction which it can use without oxygen, and which is

appreciably more productive of alcohol. Of this, naturally, we are wholly in favour!

The air-lock is also a valuable indicator as to when fermentation is finished.

As the wine ferments, it gives off carbon dioxide, which quickly builds up a pressure

within the fermentation jar or bottle, and then pushes its way through the solution in the trap with

quite a musical "blup . . . blup . . blup. " This, you will find, is quite fascinating to watch. As the

ferment proceeds, the bubbles will pass ever more slowly until finally the solution in the trap

remains poised and no more gas passes. It is then a good idea to move the jar into a warm room

for five or six days to see if any further activity develops. If not, it can be assumed that the

fermentation has finished. . . but make sure that your cork or bung is still air-tight and that gas. is

not escaping through it or from its junction with the tube of the trap, or naturally the trap will not

work. Rubber bungs are best; corks need to be waxed.

Making your own

There are several other patterns of air-lock on the market (we illustrate one or two), and

you will eventually decide for yourself which you prefer, and may well even make your own. A

plastic or glass tube leading down into an aspirin bottle or yeast phial containing sulphite

solution and secured to the fermenting vessel with sticky tape, will answer quite well, as long as

you remember to remove the phial before uncorking the jar. If you do not, the sulphite solution

will be siphoned back into your wine as you withdraw the cork and thus reduce the pressure

inside the fermenting bottle. It should be noted that this minor disaster can also happen if the

pressure inside the fermenting vessel happens to drop below that of the surrounding atmosphere,

the sulphite in the trap will be sucked back into the wine, which is bad for the wine and worse for

the temper.

This can be avoided by using two phials instead of one, and coupling them as shown in

the diagram.

Two plastic tablet-phials of any sort will do (those such as yeast is supplied in are ideal)

and you will also need some tubing such as is supplied for use with tropical fish tanks. This is

easier to use than glass, because it is smaller in bore and can be bent to shape in hot water. The

diagram is self explanatory; all joints, of course, must be air-tight. The pressure is allowed to

escape by means of a tiny hole drilled in the second phial with a red hot needle or fretwork drill.

(If small glass bottles are used cut a V-groove down the side of the cork instead.) The twin phials

can be secured by means of sticky tape.

During fermentation carbon dioxide will bubble out through the solution as with other

traps, but if the pressure in the fermenting vessel drops below that externally, the sulphite is

sucked back only into the first phial, and not into the wine.

Another simple idea is to use an ordinary rubber balloon, stretching it over the neck of the

bottle. The pressure of the gas will inflate the balloon, and when inflation ceases the ferment is

finished. For wide-necked jars or crocks one can use a sheet of polythene, secured with a stout

rubber band. This too will be bulged out by the pressure of the gas, which will escape from

beneath the band.

Other types of trap

We illustrate a kind of trap used on the Continent and becoming increasingly popular

over here because it is made in clear, non-fragile material, and is unbreakable in ordinary use, far

more so than the rather fragile glass models. It consists of a cup into which the tube from the

fermentation jar rises, and inverted over the top end of the tube is another smaller cup. Sulphite

solution is poured into the trap as shown, and when gas is given off by the ferment it lifts the

inner cup up and down to escape beneath its rim, through the solution.

Yeasts

THE essential thing to realise about winemaking. is that the most important and central

factor is the YEAST. The whole of winemaking practice really comes down to the matter of

providing ideal conditions for the yeast, a living organism, to thrive and multiply. To do that the

yeast must have sugar, it must have warmth, it must have oxygen, it must have a certain amount

of nitrogenous matter, vitamins, and some acid. The ideal "recipe" will provide all of these; if

any one of them is lacking the ferment may "stick," or temporarily stop.

Wine yeasts

ONE of the big strides which has been made in winemaking is that there are now

available to the amateur many excellent varieties of special wine yeasts, in either culture

or tablet form. Their value is unquestioned, for there are innumerable varieties of yeasts,

all with different characteristics, and just as some are more suitable for baking or

beerbrewing, so others are better for the production of quality wine. A good wine yeast

has a high alcohol tolerance (i.e., it will allow the wine to ferment further and be that

much stronger before it succumbs) it will form a firmer sediment, making racking much

simpler, and it will be less prone to impart "off" flavours to the wine.

It is possible to obtain Port, Sherry, Madeira, Tokay, Malaga, Champagne,

Sauterne, Pommard, and Burgundy yeasts, to mention only a few.

These yeasts are laboratory-cultured from the yeasts on the grapes in the place of

origin, and it is great fun to experiment with them, and see the different nuances of

flavour that they confer.

But do not imagine that you will obtain, say, a port simply by using a port yeast.

The ingredients must be suitable as well. If they are, you are certainly more likely to

obtain a port-like wine by using a true port yeast; the flavour will be unimpaired, and you

will have the other advantages already mentioned.

It is naturally advisable, when using these specialised yeasts, to employ them in

musts which will be sympathetic to them, i.e. a Port or Burgundy yeast in a red wine such

as elderberry, sloe or damson, and a Champagne yeast in a sparkling wine. The beginner

will do best, however, to experiment first with a good general-purpose wine yeast. One

can also obtain a fairly good range of yeasts especially suitable for lager, beers and ales.

Many winemakers, one must admit, still adhere to baker's or brewer's yeasts, but it

is a pity to do so without having tried some of the excellent true wine yeasts now on the

market. They are certainly worthwhile for one's "special" wines, and are by no means as

expensive as they at first appear, since they can be propagated and carried on from one

wine to another. Wine yeast, granulated yeast, yeast cultures, yeast tablets, baker's yeasts,

brewer's yeasts, liquid yeasts . . . all will make wine—of varying quality—and which

yeast you use is a matter of personal preference.

Making up a starter bottle

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 ¼ oz, baker's or

brewer's yeast.

NO yeas recipes

INCIDENTALLY, beware of all recipes which omit any mention of yeast, there is

no such thing as a "no yeast" recipe for the simple reason that without yeast there can be

no fermentation of the sort we want. Yeasts are everywhere about us—in the air, in the

soil, the bloom on fruit, in milk, in our mouths—and will find their way into a

fermentable liquor. If you use a "no yeast" recipe, you are really simply relying upon any

natural yeast which may be on the fruit you used or, if you killed that with boiling water

or sulphite, upon any airborne yeast which may find its way into your brew . . . you may

get a fermentation but the result may be not at all what you hope.

How yeast nutrient helps

TO obtain the best possible fermentation the yeast, like most living organisms,

must have both food and oxygen. Like human beings, it needs both vitamins and fresh

air! The ideal medium for fermentation is pure grape juice, which contains all the

nutrients, or foods, that the yeast requires, but some of the liquors we ferment for country

wines (notably mead and all—the flower wines) are deficient in them, and it is therefore

wise to add a nutrient to give the yeast a "boost," the nitrogenous matter mentioned

previously.

You can obtain several good proprietary yeast nutrients from trade sources, but if

you wish to have your own made up by your chemist a good formula, similar to that of

the British Bee Keepers' Association, is:—

Potassium Phosphate 30 grains

Citric Acid 130 grains

Magnesium Sulphate 8 grains

Ammonium Sulphate 60 grains

(480 grains = 1 oz.)

This is for a gallon of mead: halve the quantities for one gallon of wine.

Buy it, ready-made up, from your chemist, thoroughly mix the chemicals by

shaking vigorously in a small quantity of water in a medicine bottle, and add to the brew

at the same time as the yeast.

If you cannot obtain even this nutrient, on no account omit some acid, which is the

most important single ingredient; when making up your must, or pulp for fermentation,

include the juice of a lemon, or ¼ oz. of citric acid. If there is no acid at all in the

ingredients, about ¾ oz. citric acid per gallon of must should be added.

If, on the other hand, the recipe you are using already includes lemon juice or

citric acid, omit that in the nutrient or the wine may be over-acid. The addition of nutrient

will enable the yeast to carry the fermentation just that little further, a great help in the

production of strong, dry wines, and in the avoidance of oversweet wines. Failing all else,

use 1 dessertspoonful of malt extract per gallon.

Sugars

MANY old recipes advocate far too much sugar, with the result that the

winemaker is disappointed when the yeast fails to use most of it up, and be is left with a

syrupy, almost undrinkable concoction.

As a good rule of thumb, remember the figure 3—3 lbs. to the gallon of liquor for

a medium wine. Half a pound less will usually produce a dry wine, half a pound more a

sweet. Below 2 lbs. of sugar to the gallon the wine may not be strong enough to keep,

above 3J it may well (although not always) be sickly sweet.

So remember—2 ½ lb., dry; 3 lb., medium; 3 ½ lb., sweet.

Many old recipes, too, specify candy sugar, but this is a hangover from the days

when most sugar was unrefined and this was the best quality obtainable. Nowadays there

is little to choose, for all practical purposes, between modern refined beet or cane sugars;

they are all of excellent quality. Brown or Demerara sugar will impart a golden colour to

a wine. It is therefore sometimes used to colour an uninteresting looking wine, but it

should not be used with wines where one wishes to retain a delicate natural colour from,

say, a flower. It will also impart a slight flavour.

"Invert" sugar, too, is now available to winemakers. When yeast sets to work upon

household sugar, or sucrose, it first splits it into its two main components, glucose and

fructose, or "inverts" it. In invert sugar this has already been accomplished chemically, so

that the yeast can start immediately to use the glucose (the principal sugar found in

grapes). Thus by using invert one may well obtain improved fermentation, improved to

the extent that the yeast does not itself have to effect the inversion. Invert will ferment

more quickly than household sugar, and is widely used in the brewing industry. If you

wish to use invert sugar, use 1 ¼ lb. in place of every 1 lb. of household sugar specified in

the recipes.

Pure glucose, or grape sugar, can also now be purchased; both this and invert are

naturally slightly more expensive than ordinary domestic sugar. Honey, of course, can

also be employed to produce mead-flavoured wines. With liquid honey or with thick,

crystalline honey use pound for pound.

It is far better to make your wine dry, and then sweeten It to your taste, than

it is to put in too much sugar at the outset, hoping that most of it will ferment out.

A dry wine can always be sweetened, but there is little one can really do about a

wine which is oversweet, other than blending it with a dry one of the same type. If you

decide to sugar a finished wine and are afraid this may start it fermenting again, add one

Campden tablet per gallon to prevent this occurring.

It is also a good idea, since it eases the task of the yeast and makes for better

fermentation, to add the sugar in stages, half the total quantity at the outset, and the

remainder by stages in 4 oz. lots each time the ferment slows. Draw off a pint or so of the

wine, dissolve the sugar in it by stirring thoroughly (use no heat or you will kill the yeast)

and restore the sweetened quantity to the main bulk of the wine. Any undissolved sugar in

the wine may case the ferment to "stick."

Getting the flavour

THERE are several ways of extracting the required flavour from our fruit or

vegetables—pressing, using juice extractors, or boiling, soaking in hot or cold water, and

fermenting on the pulp—and there are advantages to each; which one uses depends on the

wine being made and the equipment available (which usually means how much one is

prepared to spend!).

Sometimes one first extracts the juice from all the ingredients and starts the

fermentation right away. The straight juice may be fermented, but for reasons of economy

(to avoid using too large a quantity of fruit) and so as not to have too strong a flavour, it is

more usual for the juice to be diluted with water.

Alternatively, the fruit is pulped, the must prepared, and the yeast introduced, so

that the fermentation begins immediately, and the liquor is not strained from the solids

until, say, 10 days later. This is more convenient for those who do not wish to buy the

more expensive equipment. Whichever system is used, the quantities advocated in the

recipes remain the same.

In the latter case it is a great help to extraction to add 1 teaspoonful of

pectin-destroying enzyme such as Pectozyme, Pektolase or Pectinol, to hasten the

breakdown of the fruit (and, incidentally, ensure a clear wine). It should be added 24

hours before the yeast, and only when the must or juice is cool or cold. (Boiling water

will destroy the enzyme.)

Pressing: ideal for grapes (which must first be broken), fruit and berries. Even if

you cannot afford the luxury of a proper press—and they are not expensive now—it is

well worth contriving one of your own or borrowing one from your winemaking club. I

have found that the ideal combination for the serious winemaker is a Bryants AK fruit

crusher with which to mash the fruit, and a Loftus fruit press with which to press it: these

will deal effectively with almost anything, even, say, a hundredweight of apples.

Extractors: the modern way Juice extractors can now be obtained quite cheaply

and range from the simple, handoperated one which is a development of the

old-fashioned mincer to sophisticated, powerful electric models such as the Kenwood,

Beekay and Vitamine. Of these I have used only the Beekay regularly, and must say that

this is winemaking de luxe, and is probably the ideal solution for someone who uses 10 or

12 lb. of fruit at a time. It is effortless; but the filter has to be cleaned out after every 4 or

5 lbs. and this becomes tedious when doing larger quantities.

Cheaper than these, or than a press, is a steam extractor, and this, like the others,

will separate the juice from the pulp most efficiently. One point to note is that fruit or

vegetables should not be left in the steam extractor for longer than 10 minutes or it will

have the same undesirable effects as over-boiling.

Boiling: (necessary with some root and fruit wines) is a method that has to be

used with care, for if the ingredients (particularly parsnips and plums) are overboiled it

may later prove difficult to get the wine to clear. The liquor is then strained off the solids,

cooled, and fermented.

Cold water soaking: the fruit is pulped or the must prepared, the yeast is

introduced, and the liquor is not strained from the solids until, say, ten days later. This

can be used with hard fruit as a preliminary to pressing. All you really need is a large

crock or dustbin.Hot water soaking: boiling or near-boiling water may be poured over the

ingredients, which are then left to soak for three or four days, the yeast having been

introduced when the must has cooled to 70 deg. F. (21 deg. C.). The liquor is then

strained off.Where boiling water is used the must will have been purified, for any wild yeast

which may have been present will have been killed, but if pressing or the cold water

method are employed it is as well to add one Campden tablet per gallon, and to wait 24

hours before adding one's chosen yeast. The sulphur dioxide of the tablet will dispose of

unwanted wild yeasts but 24 hours later its action will have abated sufficiently to allow

your, selected yeast to start working satisfactorily.

When, by one of these means, the flavour has been extracted, the sugar is added

and the yeast and yeast nutrient introduced in order to cause fermentation, and the

fermentation is then conducted as described later.

Acidity

. . . plays a vital part in determining wine quality. Lack of acid will mean a poor

fermentation, and a "medicinal" taste in the finished wine, which will also lack character

and seem insipid. In any wine it is essential that acidity, tannin content and degree of

sweetness should be "in balance" according to the type of wine being made (a sweet wine

will need more acid than a dry). A quarter of the original acidity of a must disappears

during fermentation (so that tasting one's must affords some guide) and a finished wine

should have between 5 parts per thousand (dry) and 7 parts per thousand (sweet). This, in

most recipes, will be obtained by adding the juice of one, or two, lemons, or ¼—½ oz.

citric acid.

A simple way of testing the acid content of a wine or must is to use B.D.H.

Narrow Range pH indicator paper (aim at a colour reaction equivalent to between pH 3

and 4). This is not entirely accurate but it is probably enough for most of us.

Those wanting more precision should note that the desirable acidity of table

wines, in terms of sulphuric acid, is from 4 to 6 grams per litre, according to type.

The only really satisfactory method of assessing acidity is by titration, and kits for

this purpose can be bought for as little as £l. A graduated pipette is used to take in a given

quantity of the wine to be tested and this is run into a beaker. A piece of blue Litmus

paper is added and this is immediately turned red by the acid present. A

commercially-prepared potassium hydroxide solution (11.43 grams of pure potassium

hydroxide per litre, the equivalent of 10 grams per litre of sulphuric acid) is then carefully

added, until the Litmus paper turns blue again. Note how much solution you have used

and from the chart provided you can tell the acidity of the wine. Do three such tests. and

take the average.

Tannin

A small quantity of tannin will vastly improve the taste of most wines, giving

them a zest or "bite" which is otherwise lacking, particularly in flower, root and grain

wines. It is the tannin in a wine which gives an impression of dryness in the mouth after

drinking; if the right amount of tannin is present, the wine will be supple and zestful, if

too little, flat, insipid and characterless, if too much, harsh, astringent and bitter. Tannin

is also an essential constituent if a wine is to have good keeping qualities.

Tannins come from the skins and stems of fruit—particularly red fruit, and wines

made from all red fruit, and from elderberries, bilberries, sloes, damsons, plums, apples,

pears, grapes, and oak leaves are liable to be rich in tannin, and usually need none added.

In flower and grain wines add one teaspoon of grape tannin, a few oak leaves or pear

peelings, or one tablespoonful of strong tea per gallon. It is not really practicable for the

amateur to test for tannin content.

Sometimes, particularly with elderberry wines, one has an excess of tannin. This

is caused by using too much fruit, by soaking for too long a period, or pressing too hard.

If a finished wine is a little too harsh, it can often be vastly improved by the addition of a

little sugar or glycerine, but if it is far too harsh it should be fined with gelatine or

blended with another softer wine.

Conducting your fermentation

NOW let us get on with the making of an orthodox country wine. If you are

fermenting a juice, or a liquor with no solid ingredients left in it, it can well go straight

into a fermenting jar which, however, should not be filled beyond the shoulder, and a

fermentation trap fitted. (If you fill your jar the ferment, in its first vigour, will foam out

through the trap.)

The yeast and yeast nutrient are added at the same time and the jar is placed in a

warm place, about 70 deg. F. A warm kitchen is ideal, but do not stand the jar on a stove

or anywhere it is likely to be over heated, or the yeast may be killed. After four or five

days or so the ferment will quieten, and the jar should be "topped up" to the bottom of the

neck either with some of the liquor which has been kept on one side in another smaller

bottle with a cotton-wool plug or airlock, or with syrup of the same strength as the

original liquor. The airlock, of course, is again fitted.

The jar is then best kept at a temperature of 60-65 deg. F. until fermentation is

finished. Check it regularly, particularly if you are adding sugar by stages, and watch both

specific gravity and the airlock action.

When the ferment appears to have finished, move it back into a warm room for a

few days to see if it restarts.

If you are dealing with a must with a large quantity of solid ingredients you will

probably find that, at least for the first ten days or so after the yeast has been added,

because of the great bulk, it will probably be necessary to use a crock of some sort. This

must be closely covered with several thicknesses of cloth or a sheet of polythene secured

with elastic to keep vinegar flies at bay. Again . . . a temperature of 70 deg. F. Do not

forget to stir the must from the bottom twice daily.

At the end of the soaking period strain off the liquor through a nylon sieve or two

or three thicknesses of muslin—do it thoroughly and do not hurry it—into your

fermenting jar and fit your trap, carrying on thereafter as above.

Stuck ferments

If you have used the right amount of sugar and fermentation has apparently ceased

too soon (the wine will be oversweet and its specific gravity too high) the fermentation is

said to have "stuck." Possible causes: Too high or too low a temperature; the yeast has

reached its limit of alcohol tolerance (i.e. the wine is finished); the sugar has all been

utilised (add more); too much sugar (dilute slightly); insufficient nutrient or acid (add

more); insufficient oxygen (aerate by stirring and pouring); too much carbon dioxide

(uncork and stir). If these and all other remedies fail make up a half pint starter with the

juice of three oranges, water, 1 level dessertspoon sugar, yeast, and a pinch of nutrient.

Get it going well, then add an equal quantity of the "stuck" wine. When all this is

fermenting, again add an equal quantity of the wine and continue "doubling up" in this

way until all is fermenting once more.

Racking

ONE of the most important factors in producing clear, stable wine is racking, i.e.siphoning the wine off the lees of yeast and deposited solids; more wines have beenruined by neglect of racking than from any other cause. During the first fermentation a wine will be milky or soupy—and often downright repulsive!—in appearance, and no-one would imagine that one day it will be brilliantly clear, and perhaps even sparkling.But do not dismay. Properly made, and properly managed subsequently, almost all wines will

clear of their own accord. Some wines, parsnip and plum among them, are notorious for their slowness to clear; and it should be noted that it is usually where the ingredients have

been boiled that this occurs, for boiling releases pectin to cause hazes in the wine. These hazes, however, should not be confused with the thick cloudiness of the early stages of fermentation.

A wine is likely to remain really cloudy for three or four months after the

fermentation is started because of the yeast in suspension; then, slowly, it will commence

to clear, from the top down, as the yeast and solids in it sink to the bottom, forming a

thick layer at the bottom of the fermenting jar. When the wine is visibly clearing in this

way—rack.

Place a clean jar below the level of the one containing the wine, and remove the

bung and fermentation lock. Take a yard or so of rubber tubing (about half an inch

diameter) and in one end of it fit a foot of glass or polythene tubing. Insert the tubing

carefully into the wine (carefully so as not to disturb the sediment) to about half the depth

of the jar, and hold it in place by clipping a wooden clothes peg around it, or by using a

rubber band.

Take the lower end of the tube down to below the level of the bottom of the

fermentation jar, put it into your mouth, and suck steadily (most pleasant this!). When the

wine is flowing freely direct it into the new jar. As the level in the fermentation jar drops

push the glass tube down further and further until you have racked off all the wine and

only the yeasty sediment is left. Be careful not to siphon that into the new jar.

Before fitting the fermentation lock to your new jar of semi-clear wine, make sure

that the jar is filled to the bottom of the neck, so that the minimum of air is allowed

access to the wine.

Do this by "topping up" if necessary (and it usually is) with syrup, made to the

same strength as your original liquor. Thus, if your original liquor had 3 lbs. of sugar to

the gallon (48 ozs.) use 3 ozs. of sugar in half a pint of water.

Then insert your air lock and allow the fermentation to proceed again. At first it

will probably be much slower than previously, but do not worry about this; it is because

the quantity of yeast present has been greatly reduced. As the yeast gradually multiplies

again so the ferment will get going once more, and a slow, steady ferment, rather than a

fast one, is what you want.

The wine will also continue to clear, and the yeast will throw a second deposit.

When the wine is completely clear, and the sediment is firm, comes the time for your

second racking. (The yeast left behind on this occasion will be an excellent medium for

starting off other brews.)

You may care to bottle on this occasion, but it is preferable to give the wine yet a

third racking after another two months before doing so. Normally about three months

elapse between first and second rackings but it is impossible to give a firm schedule since

the time to rack depends upon the progress of the individual wine. A good rule of thumb

is: "When in doubt whether to rack or not . . . rack!"

Racking rarely harms a wine, and generally improves it; racking helps to stabilise

the wine, thus reducing the risk of after-bottling fermentation and consequent burst

bottles; racking also prevents the wine acquiring off flavours from the dead yeast upon

which it would otherwise be standing.

Always make sure that your fermentation is completely finished before bottling,

or you may have burst bottles, which is both messy and dangerous. Most beginners fall

into the error of trying to bottle too soon, and pay dearly for their mistake.

Clearing

NORMALLY a well-made wine will clear of its own accord, given time (which

can be as much as a year in some cases) but when it does not, it may be necessary to

resort to fining or filtering. The best advice that we can give, however, is: always give

your wine a chance to clear naturally. Avoid fining, which may upset the chemical

balance of the wine, and filter only as a last resort, for filtering does take something out of

a wine besides the murkiness.

Usually all that is necessary is to move the wine, at the end of fermentation, into a

much lower temperature (say from a warm kitchen to a cold larder or outhouse, but not

into a refrigerator). In some cases, if you have some clear wine of the same sort from the

previous year, pouring some of this in on top of the new wine will rapidly clear it.

If both of these methods fail to work, it may be necessary to resort to fining. The

commercial wine world uses several types, organic (gelatine, isinglass, egg whites, egg

albumen powder, pure ox blood, casein, etc.) mineral (Bentonite, Kaolin or Kieselguhr)

and vegetable (alkaline alginates), but some of these are risky in the hands of the amateur,

since they require a reasonably exact dosage calculated as the result of experiments, and it

is difficult to work down to the smaller quantities we usually need. Many proprietary

wine finings work on the simple principle that tannins and proteins precipitate one

another and therefore add in turn some of each.

Many prefer to play safe and buy some reliable proprietary finings, with detailed

instructions; I have found "Serena" wine finings, supplied by Grey Owl Laboratories, and

Klarwunder, from Semplex, good.

Failing this, a good general-purpose fining for both red and white wines is

egg-white; one egg-white, thoroughly beaten into half a pint of the wine with a tiny pinch

of salt will clear up to 10 gallons.

For white wines try first two or three drops of milk, for red wines up to eight

square inches (i.e. 2 inches by 4 inches) of leaf gelatine. Soften it in water, dissolve in hot

water, and stir it in.

If your wine remains obstinately cloudy, you can try using filter paper (Green's

No. 940 or 960 is ideal) which should be folded in a series of vertical creases to present

the maximum area to the wine. Fold your paper in halves, then quarters, then eighths;

then unfold and refold it between the original creases, but the opposite way. It will then

present a fluted appearance. A small plug of cotton-wool placed in the funnel before the

filter will prevent a disaster if the bottom point of the filter paper gives way! These papers

are really efficient and fast-filtering, and admirably suited to the home winemaker's

purpose, unlike others which have been sold which, whilst—useful in the laboratory, are

dreadfully slow in operation, and have led winemakers to the (mistaken) opinion that

filter-papers are useless to them. Even ordinary tissues, used double or treble thickness,

will provide a reasonable filter.

But you may be looking for one method of fining or "polishing" that can be

applied to all your wines, and that can be employed for removing hazes as well. For many

years amateur winemakers preferred to use asbestos pulp, but this method is now open to

suspicion in that it may be a health hazard, and we therefore do not recommend it.

By far and away the best method of clarification is fining by means of

BENTONITE (A1203. 4SiO2.xH20.), an excellent clarifying and stabilising agent. A

montmorillonite clay which can absorb ten times its own weight of water, with which it

forms a gelatinous paste, it causes a coagulation of the proteids, which increases

proportionally as the acidity of the wine is greater and the tannin content smaller, and its

action appears almost miraculous.

It can be purchased from Semplex, Rogers Mead Ltd., Boots, and most other wine

supplies firms, and should be used at the rate of ¼ oz. of Bentonite to 3 fl. oz. of water.

Since it will keep indefinitely, but has to be made up at least 24 hours before use, it pays

to make up a quantity at a time, and preferably to do so at the outset in two small

containers, so that when one is used up it can be immediately replenished, and the

suspension in the second container will have been standing for weeks, or even months,

and will be ready for use.

Use 1 pint bottles with flat bottoms and screw caps; fruit juice bottles are ideal.

Into each bottle pour 9 fluid oz. of water (boiled and then cooled) and then funnel in 4 oz.

of Bentonite. Screw on the cap and shake vigorously, impacting the liquid against the flat

bottom of the bottle to force the Bentonite into suspension. Then leave the bottles for at

least 24 hours, and preferably more, before use, to allow the montmorillonite particles to

swell and become effective coagulators.

To use the suspension, remember that in each bottle you have ¼ oz. of Bentonite.

The advocated dose for all ordinary hazes or straightforward fining is 1/8 of an ounce per

gallon of wine, and for really bad hazes ¼ oz., so you will need to use one-sixth of the

contents for "normal" fining, and one-third of the contents for really thick hazes.

The wine should, of course, have been racked off any deposit. Draw off a little to

make room for the suspension, measure out the "dose" of Bentonite, pour it into the wine

through a funnel, and top up as required with wine. Re-cork, and then rotate or swirl the

jar gently to mix the Bentonite into the wine. Keep it in suspension for at least 20 minutes

by rocking and swirling at 3-minute intervals. Rack after a month, not before.

Egg-shells will often clear—and decolour—a white wine. Clean them, bake them

in an oven—which makes them brittle—and then crush them into small pieces before

adding to the wine. The tiny pieces will often rise and sink, rise and sink, for quite a long

time, carrying down with them the suspended solids and thus clearing the wine, or all

except the bottom quarter or so, which can be filtered.

Bottling

IT is better to use, if you can, true wine bottles (26 2/3 ozs.); they show your wine

off to better advantage. Be sure that they have been sterilised, and always use new corks

or stoppers (cork, NOT screw, stoppers).

Red wines, of course, should be put into dark bottles (except for exhibition or

competitive purposes) or they will lose their glorious colour.

The bottles can be sterilised by means of the sulphite solution already described,

and then drained; there is no need to dry them thoroughly internally. Many wine books

warn against using "damp bottles," but this is only because people have been foolish

enough to use bottles containing traces of moisture which may have been in them for a

long time, which is not only unhygienic but asking for the wine to be spoilt by the

bacteria which are inevitably present. A few drops of sulphite, on the other hand, can do

no harm. The bottle should be filled to within three-quarters of an inch of the bottom of

the cork.

Whichever kind of cork you use, soak it for 24 hours in cold boiled water

beforehand to soften and swell it, then drive it right home. When using true wine corks,

which are cylindrical in shape, a corking machine of some sort is a great help; without

one, it is difficult to force the cork in far enough. A cork "flogger" serves the same

purpose (see page 8).

"Stopper" corks, with cork or wooden projecting caps, are favoured by many,

because they lend themselves to use with an ornamental capsule, but they do not grip

quite so tightly, and are apt to be forced out again by the pressure of the compressed air

beneath them. To overcome this, put a length of thick string or pliable wire inside the

neck of the bottle, leaving sufficient projecting to be able to grasp it firmly. Insert the

cork and drive it home. Then, holding down the stopper with the thumb of the left hand,

grasp the string or wire with the right, and pull it out. As it comes out it makes a path

which the compressed air follows, thus leaving no pressure within the bottle. Whichever

kind of cork you prefer, always try to use new ones (and never one which has been

pierced by a corkscrew). If you have to use an old one, boil it first.

One of the most popular stoppers of all nowadays are those made in polythene

—Messrs. Bryants and others supply them—which can be used over and over again, and

sterilised each time by boiling. They are neat, cheap, and ideal for the home winemaker.

Corks can be wired or tied down as shown on page 39, but the job can be done

even more neatly with proper wire loops and a hand wiring tool.

Finally, finish your bottle off with an appropriate label and coloured capsule of

tinfoil or plastic to cover the cork. (It looks better if label and capsule match, and are of a

suitable colour for the wine, red label for red wine, yellow for yellow, and so on.) On as

ordinary wine bottle the label should be about a third of the way dawn the body of the

bottle, i.e. the top of it should be about 1 ½ in. below the shoulder, so that the main line

of printing is in the "optical centre." and looks attractive. The label should be centrally

placed between the seams of the bottle and not overlap them, or the appearance is spoilt.

Store your bottles on their sides, in a rack or bin if you can, and preferably in a

temperature of about 55 deg. F. in a place which is free of vibration and not brightly lit.

The malo-lactic fermentation

OCCASIONALLY one comes across what is really a third fermentation, the

malo-lactic fermentation. This occurs usually after the wine has been bottled, and often as

much as a year or more after it was made. It is something which should be welcomed,

when it does occur, for it imparts a very pleasant freshness to a white wine, and does

reduce the acidity a little. For this last reason it is important to the winemakers of Austria,

Germany and Switzerland, whose grapes tend to contain slightly more malic acid than

those from sunnier regions, where the sun will have accounted for most of it before the

wine is even made.

Malic acid is the acid to be found in apples, and what happens during the

malo-lactic fermentation, as the name indicates, is that a bacterium to be found in all

fresh wines (b. gracile) sets to work on the malic acid and converts it into lactic acid. This

might not seem much of an improvement, but lactic acid is much less acid than malic,

and the acidity of the wine is thus reduced, to say nothing of the very pleasant, clean,

freshness with which this slight fermentation endows the wine.

Occasionally, one can bring about such a fermentation by agitating any yeast

deposit and bringing the wine into the warm, but usually one can only be duly grateful if

it occurs of its own accord

Sparkling wines

A MALO-LACTIC fermentation will give you a sparkling wine accidentally, as it

were, but it is even more fun to make one deliberately. All you need is a suitable

must—apples, pears, gooseberries, rhubarb are all ideal ingredients—a champagne yeast,

and not too much sugar (about 2 ½ lbs. to 1 gallon, or an S.G. of 1080-1085, giving a

wine of about 10 %). Ferment this to dryness, rack twice, mature for about six months,

and then bottle in champagne bottles, adding to each 1 level teaspoon of sugar and a little

fermenting champagne yeast. Cork well with a true cylindrical wine cork and wire it

securely. Mature for at least three months. Do not make this wine in ordinary wine

bottles; they will not stand up to the pressure involved.

If you wish to make an "instant" sparkling wine and are lucky enough to possess a

Sparklet siphon you can do so in this way. First chill the wine in the refrigerator. Pour a

bottle into the siphon, screw on the cap, insert a cartridge, turn the siphon upside down,

and discharge the cartridge. By inverting the siphon the bottom of the tube inside it will

be at the top and will be projecting above the surface of the wine. Turn the siphon up the

right way again. Store it in a cold place if it is to be kept for a while before use. To serve

the wine, do not squirt it out through the nozzle but unscrew the cap and pour out the

wine as from a bottle. Hey presto!—Sparkling wine!

Winemaking summarised

Ÿ 1. Extract flavour.

Ÿ 2. Add sugar and yeast and ferment for up to 10 days in a bowl or crock, closely

covered, at about 70 deg. F. (This may be simultaneous with (1) ).

Ÿ 3. Strain off, put into fermentation jar or bottle; fit trap. Fill to bottom of neck.

Temperature: about 60 deg. This fermentation will be much quieter and will

proceed for some weeks.

Ÿ 4. Rack the cleared wine. Repeat this about two months later, and, usually, a third

time after a further month. By then the wine should be quite stable, with no

risk of burst bottles later on.

Ÿ 5. Bottle when the wine is about six months old. Store bottles, on their sides,

preferably in a room of 55 deg. temperature or below.

The hydrometer

IF the fermentation trap is the winemaker's best friend, it is certainly run a close
second by the hydrometer. A hydrometer is by no means essential to the production of
good wine, but it is a great help, particularly if one is aiming at consistent results.
Many winemakers seem to fight shy of it but in principle it is quite a simple
device; by means of it one can:
(a) determine how much sugar there is in any natural juice or must;
(b) determine how much sugar to add to a juice to produce a wine of the desired
strength;
(c) keep a check on the progress of a ferment; and
(d) calculate the strength of the finished wine.
The word hydrometer means "water-measurer," but in this instance it would be
more accurate to call it a saccharometer, or "sugar measurer" for the basic purpose of the
instrument is to discover how much sugar there is in the liquor. Fermentation, as has been
explained, involves the conversion by yeast of sugar into alcohol and carbon dioxide. If,
therefore, we can discover how much sugar is used up during the whole course of a
ferment, we can calculate exactly how much alcohol has been produced, how strong the
wine is.
The more sugar there is in a liquid, the thicker or denser it will become, or the
greater its gravity will be: The better, too, it will support anything floating in it; the
hydrometer makes use of this principle. To measure different gravities, we naturally need
a scale of some sort, and an obvious and convenient standard from which to start is that of
water. Water is therefore given the arbitrary gravity of 1.000, other liquids are compared
specifically with this, and the resultant figures are said to be their specific gravities.
Thus liquids heavier than water (or, in our case, containing more sugar) may have
specific gravities such as 1.050, 1.120 or 1.117 degrees. When talking of gravities,
however, we omit the first "1" and the decimal point. Therefore the specific gravities
quoted are exactly the same as gravities of 50, 120 and 117 respectively: Gravities are the
same as degrees Gay Lussac (deg. G.L.).
For winemaking you will need hydrometers, or perhaps one hydrometer, covering
the range 1.000 to 1.160, and it is often useful to be able to go several degrees below the
1.000.
If you wish, buy three, one 904 to 1.000, one 1.000 to 1.100 and one 1.100
to 1.200. You will then be equipped with hydrometers the gradations of which will be
larger and more readable.
Messrs. W. A. E. Busby, however, produce one which is specially designed for
the winemaker and which allows one to calculate the strength any wine has attained
without reference to tables or graphs, which is most useful. This hydrometer has the
specific gravity and the potential alcoholic strength scales side by side, and it costs no
morn than an ordinary hydrometer. Moreover, it covers the whole of the scale, 0.990 to
1.170, that the winemaker is likely to need, and is therefore ideal for our purpose.
Semplex and Messrs. H. T. Ellaway also have specialised models.
A hydrometer is a glass tube (with a bulbous lower end) containing the scale, and
it is weighted at the bottom so that it will float upright in a liquid. The reading is taken
when the level of the main surface of the liquid would cut the scale.
The thinner the liquid (the less its gravity) the deeper the hydrometer will sink in
it; the denser the liquid (the greater its gravity) the higher the hydrometer will float, and
the more of the scale will protrude above the surface.
Therefore the scale of figures in the hydrometer is "upside down," the smallest
being at the top and the largest at the bottom. In water, of course, the hydrometer will
float with the 1.000 mark level with the surface; as you add sugar so the hydrometer will
rise is the liquid. If, on the other hand, you add instead to the water a liquid lighter than
water—alcohol, for instance—the hydrometer will sink below 1.000.
To use your hydrometer, pour some of the juice or syrup to be measured into a
hydrometer jar, or any transparent container that gives sufficient depth and ample side
clearance. Spin the hydrometer to get rid of any air bubbles clinging to its sides, which
can seriously affect the reading. When the hydrometer is still, take the reading, with the
eye at surface level.
Note that hydrometers are designed to be read when the liquid is at 59 deg. F.,
and, strictly speaking, if it is at any other temperature, you should allow for it as shown in
the table below. Omit the "decimal point" of the specific gravity and make the correction
to the last of its four figure. Example: A hydrometer reading of 1140 at 86 deg. F. should
be corrected to 1143.4.
50 Subtract 0.6 77 Add 2
degrees F degrees F.
in Correction in Correction
Temperature Temperature
68 Add 0.9 95 Add 5
59 Correct 86 Add 3.4
104 Add 6.8
When you have measured the specific gravity of your juice or liquor, you can tell
from the table below firstly how much sugar per gallon it contains, and secondly, how
much alcohol (in terms of the percentage of alcohol by volume): it is likely to produce,
i.e. you can assess its potential alcoholic strength. This, remember, on the assumption that
the wine ferments right out, and that all the sugar is used up.
There may be some obscuration, or unavoidable inaccuracy, at either end of the
scale, caused by solids initially, and alcohol finally, but these figures give a practical
working basis, and a deliberately conservative estimate of potential alcohol.
Let us assume that you wish to make a wine using a diluted fruit juice. Having
extracted the fruit juice and diluted it with water as required, take the S.G. of it. Let us
assume that you obtain a reading on the hydrometer of 1.040. This means, if you look at
the table for a moment, that there is already 1 lb. 1 oz. of sugar present in the natural juice
and that if you fermented it you would finish up with a dry wine of 5 %. alcohol by
volume. This would probably not keep (under 10 % it cannot be guaranteed).
So you. now have to decide how strong a wine you wish to make. One can, of
course, make a weak wine of, say, 5 %, but it would have to be drunk young, and most
winemakers prefer to make table wines, which are usually of about 10-12 % alcohol, or
stronger wines of up to 17 %. For wines of above the latter strength, say for drinking after
a meal, one must resort to fortification.
Say you deride to make a dry wine of 16 % alcohol. The table shows you that this
will require an initial S.G. of 1120, or a sugar content in the gallon of 3 lb. 2 oz. You
already have 1 lb. 1 oz., so that you need to add 2 lbs. 1 oz. of sugar, and make the
quantity up to 1 gallon with more juice of the same dilution.
1135 18.4 3 8 4 7 1 42
1130 17.7 3 6 4 4 1 40
1125 17.0 3 4 4 1 1 38
1120 16.3 3 2 3 14 1 37
1115 15.6 3 0 3 11 1 35
1110 14.9 2 14 3 8 1 33
1105 14.1 2 12 3 5 1 32
1100 13.4 2 10 3 2 1 30
1095 12.7 2 8 2 15 1 28
1090 12.0 2 6 2 12 1 27
1085 11.3 2 4 2 9 1 25
1080 10.6 2 1 2 6 1 23
1075 9.9 1 15 2 4 1 22
1070 9.2 1 13 2 1 1 20
1065 8.6 1 11 1 14 1 19
1060 7.8 1 9 1 11 1 17
1055 7.2 1 7 1 9 1 16
1050 6.5 1 5 1 7 1 14
1045 5.8 1 3 1 4 1 13
1040 5.1 1 1 1 2 1 11
1035 4.4 15 1 0 1 10
1030 3.7 12 13 1 8
1025 3.0 9 10 1 7
1020 2.3 7 8 1 5
1015 1.6 4 5 1 3
1010 0.9 2 2 ½ 1 1
Vol. of
one gallon
with sugar
added
gal. fl. oz
Amount of
sugar
added to
the gallon
lb. oz.
Amount of
sugar
in the
gallon
lb. oz.
Potential
%
alcohol by
Volume
S.G.
Alternatively, you can take 1 gallon of the juice and, in order to get the extra 80 degrees
gravity required, add 2 lbs. 6 oz. sugar, in which case you will finish up with 1 gal. 1 pint
3 ozs., because of the extra bulk of the sugar. You can, of course, add all the sugar of the
outset, as long, as you ensure that it is thoroughly dissolved, and, if you then check with
your hydrometer, the S.G. should be in the region of 1.120. Add a tittle of the sugar at a
time to be on the safe side, testing as you go. A simple approximation is that 2 ¼ oz.
sugar will usually raise the S.G. by 0.005 (5 degrees).
You then add your yeast nutrient and ferment in the usual manner.
As the ferment proceeds the S.G. of the liquor will drop, rapidly at first, and then
more slowly, and you can gain a good idea of its progress by noting the rate of drop. As it
nears the 1.000 mark it will be very slow indeed. It may reach the 1.000, and may even
drop below because of the presence of alcohol, in which case congratulate yourself upon
having produced a really dry wine!
To calculate the final strength of the wine, write down (omitting the decimal
point) the S.G. at the start of the ferment (i.e. after the sugar was added). Subtract from it
the final S.G., and divide the answer by 7.36; that is the percentage of alcohol. by volume
in your wine.
Multiply that by 7/4ths and it will give you the strength as proof spirit.
Example: Starting S.G.....1125
Final S.G.... 1002
-------
Drop ....... 123
-------
123 ÷ 7.36 = 16.7 % alcohol by vol.
Multiplied by 7/4ths = 29.2 deg. proof.
It is always good practice in winemaking to add the sugar by stages, but
winemakers are often puzzled as to how they can do this, yet still use their hydrometer to
obtain the information they want as to their wine's strength. It is easy enough if one bears
in mind all the time that the principal factor with which one is concerned in calculating
the final strength of a wine is the total drop in specific gravity. The sugar can therefore
well be added a few ounces at a time as long as you keep a record of the number of
degrees drop between successive additions. Then add up the various drops, and this is the
figure to be divided by 7.36 in the usual way. This will in normal cases give an
approximate result which will be accurate enough for the average winemaker, but where
large quantities of syrup are added it can be seriously adrift because it takes no account of
the volumes involved. When you have worked out what percentage of alcohol you have
obtained by the first drop, you then proceed to add sugar or syrup. This produces more
alcohol, but its bulk also dilutes the alcohol you have already produced, so you must
modify the calculation already done. Similarly the drop from the second lot of sugar must
be modified, and so on.
Suppose you start with an S.G. of 1100 and, after three or four days, strain into a
one-gallon jar and obtain 5 pints of liquid. Some time subsequently the S.G. is found to
be 1000, i.e.. a drop of 100. Since a gallon is required you "top up" these 5 pints, bringing
them to 7 ½ pints with an S.G. of 1010. After another period the S.G. drops again to
1005, so once more you top up with syrup or sugar to obtain a full 8 pints with an S.G. of
1010. The S.G. finally drops to 1005.
Using the rough-and-ready calculation above gives a total drop of 100 + 5 + 5 =
110. This one divides by 7.36, giving a result of 15 % alcohol by volume.
But the correct calculation would be:—
First drop: 100.
This must be modified into
5 (the number of pima before topping up)
100 x --
7 ½ (the number of pints after topping up)
=100 x 2/3 = 66,6
Second drop: 5.
Added to modified first drop = 66.6 + 5 = 71.6
This again must be modified due to the second addition of sugar, as follows:
7 ½
71.6 x -- = 67
8
Final drop: 5.
To this 67 is added the final drop of 5, giving a total effective drop
of 67 + 5 = 72. This represents just under 10 % alcohol by volume,
as against 15 % by the crude method.
Admittedly this is an exaggerated case and does not illustrate good winemaking
practice, but it does illustrate the mathematical point.
A good general rule is that a really dry wine will often need a starting specific
gravity of about 1.085, a medium sweet wine one of about 1.100, and a really sweet wine
one of up to 1.125.
Always remember that it is better to use too little sugar initially than too much; a
dry wine can always be sweetened; an oversweet wine is hard to redeem. Make your
wines dry, and sweeten them to taste when finished.
Another useful point to note is that if you wish to reduce the gravity of a liquid, it
can be done by dilution. The addition of an equal quantity of water, for instance, will
reduce the gravity by half.
PEARSON SQUARE
SOMETIMES you will want to fortify a wine (raise its alcoholic content by
adding spirit) and, since spirit is expensive, you will need to calculate exactly how much
to add to achieve the desired result. Do so by means of the Pearson Square (or St.
Andrew's Cross) but note that all measures must be of the same sort, i.e. degrees Proof or
% alcohol by volume; do not mix them.
Here is the Pearson Square:
A = alcohol content of spirit to be added
B = present alcohol content of wine
C = desired alcohol content
D = difference between B and C
E = difference between C and A
The proportion D to E is the proportion of spirit to wine to achieve the desired
strength.
If you are blending two wines of known strength and wish to know the final
strength, the formula is:—
(A x B) + (C x D)
---------------------- where:
A + C
A = No. of parts of 1st wine
B = Strength of 1st wine
C = No. of parts of 2nd wine
D = Strength of 2nd wine
Thus, if you blend two parts of a wine of 15 % with three parts of a wine of 10 %
the result will be:
(2 x 15) + (3 x 10) 60
----------------------- = --- = 12
2 + 3 5 or a wine of 12 %