The science and magic of… fruit wine

Andy Connelly
Friday 25 October 2013

… a new friend is as a new wine; when it is old, thou shalt drink it with pleasure.

Ecclesiasticus 9:10

I grew up on tales of my Dad’s 1970s homemade hedgerow wines. Their fruity aroma and potency were legendary. All that remains of this heady era are five very dusty bottles of “vintage” wine sitting in my father’s garage. Of what vintage, or even of what fruit these wines are made, has been long forgotten. But the bottles, and a glut of apples and blackberries, inspired me to start making my own wine. Beautiful jewel-coloured liquids and the constant plop of air locks have formed a backdrop to my living room ever since.

Many microbes are capable of obtaining energy by consuming sugars, and many liberate the alcohol ethanol as a by-product. Unfortunately for the microbes, they are also producing their very own poison. Ethanol will kill most microbes even at low concentrations. Fortunately for us, yeast is different. It can survive in up to about 20% ethanol before it is overcome, and for millennia we have made use of this ability in many fruitful ways.

The truth is that Dad’s “vintage” wines have taken the inevitable final step of fermentation: their alcohol has turned to vinegar. In fact it is vinegar, not wine, that is God’s gift to man; all we can do is hold it a little while at the wine stage.

It was only when we moved from being hunter-gatherers to agriculturists about 8,000 years ago that we could accumulate enough grapes for winemaking to begin. From this point on grapes held sway in winemaking because of the ease with which they can be turned into wine. Even the word “wine” has the same ancient root as “vine”. However, almost anything can be used to blush water into wine: fruits, vegetables, flowers, spices, teabags – whatever you think might taste good.

The recipe

Whatever ingredients you choose, the basics are the same: get the right balance of flavour, sugar and acid, add some yeast, and away you go. The following will work for most fruits. For strong-tasting fruits like elderberries use slightly less fruit (say 1.5kg). For fruit with gentle flavours, such as apples and grapes, you can use the pure juice (but then use less sugar).

  • About 2kg fruit
  • 1.5kg sugar
  • 4.5L water
  • Packet of yeast (normally 5g)
  • Pectic enzyme
  • Lemon juice
  • Strong tea (alternatively, use raisins or tannin extract)

Stage 1 – prepare the fruit

When making wine it is important to control the microorganisms that grow. Wild yeasts and bacteria exist all around us and for much of the history of wine were used to ferment the fruit into alcohol. Unfortunately, many of these will produce unpleasant flavours and some can make toxins. To ensure that only the microbes you have chosen grow, make sure you sterilise all your equipment before you start.

To prepare the fruit, first remove any stalks and leaves – you can remove skins if you want but you will lose lots of colour and flavour. Next, crush the fruit in a large plastic food-grade bucket. Sterilise the fruit by adding boiling water to your bin. This has the advantage of killing most microorganisms but may affect the flavour of the fruit. Alternatively, use normal tap water and add a Campden tablet. Invented in the eponymous Cotswold village, Campden tablets release sulphur dioxide into the mixture. This will kill most bacteria and will inhibit the growth of most wild yeasts. The rest will die later as the alcohol content rises above 5%.

Allow the water to cool to below 50C and then add some pectic enzyme. Letting the water cool will avoids damaging the enzyme, which breaks down the networks of pectin molecules that help hold plant cell walls together. By breaking these down, more juice is released and we avoid the formation of “pectin haze” in the finished wine. Letting the water cool before adding avoids damaging these little chemical factories.

Leave this mixture, or “must”, for 24 hours to allow the juices to escape the fruit and the sulphur dioxide to disperse. If you add the yeast now, the bubbles created can push fruit to the top of the bucket and out of the water, reducing flavour transfer.

Stage 2 – open fermentation

Before we can start fermentation we need to add sugar to the must. The type of sugar you use depends on which kind of flavour you’re after: cane sugar, beet sugar and brown sugar will all produce different effects. Whichever you choose, the yeast will work its way through the sugar until it is used up or until so much alcohol is produced that the yeast dies. This recipe will give a wine with about 13-15% alcohol. You are now ready to add your yeast, the miracle that makes wine work.

Once you have added, or pitched, the yeast into the must give it a good stir. Over the next 24 hours you can watch as the calm wine-dark sea is disturbed by bubbles of carbon dioxide coming to the surface. Yeast can live with or without oxygen but it can create much more energy with it, so we start our fermentation open (but covered) to allow the yeast to multiply and completely take over the must.

As the yeast cells respire, a stormy raft of bubbles will form and a dark earthy smell will erupt from the depths. You should leave this mixture for 5-7 days in a warm place (18-24C), stir it each day and watch as the yeast makes it “boil”. It is this process that gives fermentation its name, from the Latin word fervere, “to boil”. There are many species of yeast but most winemaking is done using the reliable Saccharomyces cerevisiae. There are hundreds of strains of C cerevisiae, each releasing different flavours and surviving different amounts of alcohol, so the choice is yours.

In addition to sugar, yeast requires various nutrients in order to flourish. It needs amino acids, (poly)phenols, various B vitamins, acids, and minerals (such as phosphates). Insufficient nutrients may result in a “stuck” fermentation. Unfortunately, most fruit does not contain all of these nutrients and so additions need to be made. Even commercial vintners make nutrient additions, although they don’t shout about it. While you can buy commercial formulations, I have always found that tap water, a cup of strong black tea, and some lemon juice provide enough nutrients for a lovely fermentation.

It is also important to balance the level of acidity in your wine. Acidity gives tartness to your wine: too little and you get a flat, lifeless wine; too much and the wine tastes “sharp”. The optimum acidity of your wine is about pH 4.5-5.5 and so for some fruit you may need to add citric acid in the form of lemons (up to three for low-acidity fruits) or as tartaric acid from raisins. Since citric acid is partly used up during fermentation tartaric acid will be a useful addition for very low acidity fruits; it is also a good yeast nutrient. Alternatively, you could add a commercial acid blend.

Stage 3 – fill the demijohn

Now that the yeast has gained a strong hold over your must, we need to seal it away from dangerous oxygen – that which once fed your yeast could now ruin your wine. Removing oxygen forces yeast to produce alcohol and stops bacteria from turning that alcohol into acetic acid, or vinegar. Transfer your must to a sterile demijohn using a large funnel and an old but clean tea-towel to filter out the fruit pulp.

Once you’ve filtered it, have a taste. Hopefully you have a sweet fruity liquid with a hint of alcohol. If there is any space left in the demijohn, fill it up to just below the neck with clean water. When the demijohn is full put an airlock in the top; this will let the carbon dioxide escape but keep the oxygen out.

Stage 4 – closed fermentation

Left in a cool, dark place, your cloudy, sweet liquid will gradually turn into a clear, alcoholic one: a fantastically pleasing sight, accompanied by the hiccupping sound from the airlock that lets you know the yeast is still working.

Over the next few months, exhausted yeast cells will sink to the bottom of your demijohn, forming a deposit known as “lees”. These dead yeast cells are digested by their own enzymes and their “guts” get released into the liquid, generating flavour. However, if you leave this sediment too long it will start to decompose and release unpleasant flavours. To avoid this, transfer the wine to a new demijohn when there is 1-2 inches of sediment at the bottom. This is called racking. You might need to repeat this several times, but ensure that you always carefully minimise contact with oxygen. Top up with clean water after each racking.

After about nine months the fermentation should finish, the bubbling should come to an end, and the wine should be clear. You can check the yeast has finished producing alcohol by moving the demijohn to a warm place for a few days to see if that wakes it up.

Stage 5 – bottle

Bottling is a dangerous stage when your wine can catch “the wine disease” and turn to vinegar. To avoid this, Pliny suggested adding tree resin; later winemakers found that adding brandy helped prevent it and so invented sherry. We now know that it is bacteria that cause the disease and we can stop them with a Campden tablet. The sulphur dioxide released into the demijohn will kill the bacteria and also act as an antioxidant during bottling.

You are now ready to bottle your beautifully clear wine. Siphon it into sterilised bottles, being careful not to carry sediment over. I always put my new wine into old bottles. You’ll need six.

This is another tasting opportunity: run some of your “nouveau” wine round your mouth. Is it fruity, sweet, tart, or astringent?

Stage 6 – ageing

One of the appeals of wine is that left in a cool dark place it will continuously change. Flavours and aromas will develop and improve. Unfortunately, the process is very complex, so it is not possible to predict from bottle to bottle when flavour and aroma will peak. There are interactions between hundreds of different compounds, all of which contribute towards the ultimate flavour, aroma and structure of the drink.

One set of such compounds are the tannins. Tannins are the third most important feature of a wine’s flavour after sweetness and acidity. They are phenolic compounds that are common in darker fruits such as elderberries and red grapes, especially in the skins. They bind to the proteins in our saliva, inhibiting its ability to lubricate the mouth, causing a puckering, astringent feeling.

Some fruits, such as strawberries, lack tannins and so do not have the “mouth feel” of good wines; for these, tannin-rich black tea is an important addition. As wine ages, excess tannins slowly bind together in long chains and fall to the bottom of the bottle as sediment, allowing the wine to mellow. The more tannins in your wine, the longer you’ll have to age it. For example, elderberry wine might need two years before the tannins mellow and it reaches its peak. I leave all my wines for at least six months before I take a sip to see whether it is ready to share with others.

Stage 7 – drink!

Few things compare to the pleasure of sharing a glass of your homemade wine with your friends while plotting how you are going to fill your next demijohn. I hope that your wine will be the finest wine known to humanity … or at least your corner of it.

Further Reading

Image provided by florriebassingbourn (


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