Tag Archives: wine

Bottle variation

Bottles of the same wine may taste very different, and variations increase as a wine gets older. In fact one bottle of a mature wine may be wonderful, and the next over-the-hill. Why?

different bottle sizes

different bottle sizes

The blend
Virtually all wine is a blend from different barrels or vats. If the mixing vat is not big enough to take all the wine, then one batch may well differ from the next. So, there may be a difference before the wine is even bottled.

Bottling
A particular wine may be bottled in batches rather than all at the same time. The fill levels, added sulphur dioxide, entrained oxygen, and gas injected above the wine may all vary at each bottling session.

The closure
Historically this was always natural cork. It is a fine closure, but every cork is different and will allow differing amounts of air to diffuse through. This causes bottles to mature at different rates. One big advantage of screwcaps is that each closure is the same.

Transport and storage
This is a major issue, and can completely destroy a wine.

  • Temperature – is covered in more detail by another post. If the temperature gets too high, the wine will be damaged, perhaps fatally. Cases of wine stored at different temperatures will mature at different rates.
  • ‘Lightstrike’ – damage by over-exposure to UV light.

Bottle size
The larger the bottle, the more slowly and gracefully a wine matures. This may just be because the gap between the cork and the wine is the same for a half bottle, a bottle or a magnum. Any air in that gap will be spread more thinly in a magnum than a half bottle, meaning that it will be oxidised more slowly.

Age of the wine
The older a wine, the more time there is for all these influences to take effect, and the higher the chance of one bottle being very different to the next.

The serving temperature of a wine is important

A wine’s serving temperature is probably the most important factor in your enjoyment. It won’t make a great wine out of an average one, but it will make the most of what you’ve got.

Red wine serving temperature

Red wine serving temperature

Serving reds at room temperature
The adage used to be – serve a red wine at room temperature. That was fine in the days before central heating, but now ‘room temperature’ is usually over 20ºC (68ºF) , which is just too high. Any red wine is just bland if it is too warm.

White wine serving temperature

White wine serving temperature

Serving dry whites straight from the fridge
A domestic fridge can get a bottle down to 5ºC (41ºF), if you leave it in there for long enough. At that temperature the wine will just numb the taste buds, and you won’t smell much either.

Serving sweet white wines
These should be served well-chilled, 8°C to 10°C, 46°F to 50°F, is a good guide. Lighter sweet wines can be served at even lower temperatures. Lower temperatures make sweet wines less cloying.

Serving sparkling wine
Freshness is important in a sparkling wine, so its temperature should be lower than a dry white. Serving straight from the fridge at a little over 5ºC (41ºF) is ideal.

The affect of ambient temperature
Once a wine has been poured, its temperature will quickly move to that of its surroundings.

  • If it’s a warm day, then start the wine at a lower temperature.
  • If the weather is cold, then serve the wine at the correct temperature – you can always warm it up in your hands.

The 20 minute rule
This is as simple a rule as you are likely to get. 20 minutes before a meal:-

  • put the red wine into the fridge.
  • take the white wine out.

Is there a perfect temperature for storing wine?

temperature and humidity recorder

temperature and humidity recorder

Wine is an organic living thing. The temperature a wine experiences can have a big influence on its quality.

So, is there a perfect temperature?
Time has shown that deep cellars in temperature parts of Europe are perfect for wine storage. A constant temperature of around 12°C (54°F) is ideal. A high humidity prevents the cork from drying out.

Increased temperature leads to increased reaction rates
Wine is a complicated mixture of chemicals, which react with each other. As the temperature rises, all of the reaction rates will increase, but some will increase more rapidly than others.

Increased temperature leads to new reaction products
As the temperature rises, new reactions will occur, which simply wouldn’t happen at 12°C. An example is the breakdown of aromatic chemicals in dry white wines. Unpleasant compounds are also produced.

Wines with low sulphites/sulphur dioxide
Natural wines with low levels of sulphites (sulphur dioxide) are increasingly popular. Sulphur dioxide serves two very useful functions:-

  • to limit oxidation of the wine.
  • prevent bacterial growth.

Both of these become much more of an issue as a wine’s temperature rises, and natural wines are particularly vulnerable.

Unfiltered wines
If the temperature gets too high, it is perfectly possible to restart fermentation . This causes plenty of problems.

What if the temperature is lower than 12°C (54°F)?
As the temperature decreases, the reaction rates slow down. So, a wine may not mature in the normal way, but at least it won’t go off. If a wine gets cold enough it may deposit white tartrate crystals, but these do no harm. The alcohol in wine depresses its freezing point, so it needs to be well below 0°C (32°F) before it even starts to freeze.

Conclusion
If you live in a climate where the temperature is above 25°C (77°F), and you don’t have dedicated wine storage, then please keep ALL your wine in a domestic fridge. You will have to remember to take the red out in good time before drinking it, but at least the wine will be in good condition.

Putting the fizz into sparkling wine

Sparkling wines are more popular than ever, as they are lively and refreshing. How are they made, and what produces the bubbles?

Champagne cork and muzzle

Champagne cork and muzzle

Where do the bubbles come from?
Sparkling wines have carbon dioxide dissolved under pressure . When the bottle is opened, the pressure is released and the gas starts to evaporate. Bubbles form on irregularities on the glass, or material suspended in the wine.

What if there are no bubbles?
The main reason for bubble-free sparkling wine is dirty glasses. There is nowhere for the bubbles to nucleate.

What is the gas pressure within a bottle?
Champagne usually has a pressure of around 6 bar – 6 x atmospheric pressure – at room temperature. Which is why you get a mess if you open a warm bottle. The pressure decreases rapidly as the wine is chilled, which is one very good reason for serving cold Champagne. Other sparkling wines have a similar, or lower pressure.

Where does the carbon dioxide come from?
When sugar ferments in the presence of yeast, it produces alcohol and carbon dioxide. The more sugar you have, the more alcohol and carbon dioxide is produced.

  • In most sparkling wine production, grapes are fermented to a still wine. Sugar and yeast are added, and the second fermentation produces carbon dioxide for the sparkle.
  • In some rare cases there is just one fermentation, and the carbon dioxide retained, rather than allowed to evaporate.
  • The cheapest way of introducing the gas is to inject it into still wine, but this produces a coarse result.
Stopper to keep the fizz in a bottle

Stopper to keep the fizz in a bottle

Producing bubbles using a second fermentation
Starting with a still wine, there are three main methods for producing the bubbles:-

  • The method used in Champagne, now generally known as the ‘traditional method’. Wine is put into a bottle, along with sugar, yeast and nutrients. This second fermentation produces carbon dioxide. The debris is removed, and the wine sold in the same bottle.
  • The transfer method, in which secondary fermentation is in a bottle, but the wine is then transferred to a vat, where the debris is filtered out. The wine is sold in a different bottle.
  • The Charmat or Tank Method, where the second fermentation is carried out in tanks. The wine is then filtered and bottled under pressure.

The quality factor
Quality sparkling wines undergo a number of processes and maturation to give the same depth and complexity as a fine still wine, but they also have the prickle of bursting bubbles on the tongue.

Alcohol levels in wine – high or low?

Alcohol levels in wine have increased significantly over the past 20 years. That is not to everyone’s taste, but are low and zero alcohol wines worth considering?

Why have alcohol levels increased?
There are several proposed reasons, including:-

  • Climate change – more heat and sunshine produces riper grapes with more sugar, and hence more alcohol.
  • Better practice in the vineyard, producing better quality grapes, with higher sugar levels.
  • The influence of certain wine critics, which encourages big wines with high alcohol levels.

What influence does alcohol have on your palate?
Alcohol stimulates nerve endings in the mouth, to provide a sensation of body and texture. It spreads flavours around the mouth, which persist even after the wine has been swallowed – known as the ‘aftertaste’. If the alcohol is too high, and is not balanced by the fruit, then the aftertaste may be bitter. If the alcohol is too low, then the wine is thin and unappealing.

Bottle of lower alcohol wine

A quality wine with 9% alcohol

Lower alcohol wines
The most successful lower alcohol wines (less than 10%) are those made in Germany. The fermentation is stopped short, and the wine may be sweetened by adding unfermented grape juice. This combination of lower alcohol, sugar and good acidity works very well indeed.

How low and zero alcohol wines are made
A wine has to be made by fermentation of grapes; this produces mainly alcohol, but also a host of other chemicals which contribute to a wine’s taste and smell. So the alcohol needs to be stripped out, but this is likely to remove other compounds as well.

Why drink very low or zero alcohol ‘wine’?
For the reasons stated, these ‘wines’ are a mere shadow of their former selves. So why not drink unfermented fruit juice instead?

Suggestions if you are worried about alcohol consumption:-

  • Look for wines from cooler regions of the world, which will have lower alcohol levels.
  • Drink less.
  • Add water to high alcohol wines. I know this may be sacrilege, but it is better than commercially stripping out the alcohol. Please don’t add fizzy drinks unless you hate the wine, as this completely disguises what you are drinking.

Preserving wine once a bottle is opened

Once a bottle is opened, most wine has a very limited life. All but very mature wine will improve for a while when exposed to the air, but over time all wine will oxidise and become unpalatable.

The best thing to do with a bottle of wine is to drink it all at one sitting. If you fail to do that, then there are several options for preserving it in good condition for a few days.

Refrigeration

Chilling any wine, including reds, will help to preserve them. All reaction rates, including oxidation by air, will decrease at low temperatures.

Vacuum systems

vacuum stopper

vacuum stopper

vacuum pump

vacuum pump

These pump air out of the bottle. The less air there is, the less oxygen is around to spoil the wine. The problem with hand-held systems is that you are likely to remove some of the desirable chemicals as well. Commercial systems claim to pump the air out more precisely, without affecting the volatile compounds in the wine.

Inert gas systems – hand-held

The gas cannister dispenses an inert gas on top of the wine; this is heavier than air and displaces it. Pouring wine from a bottle will agitate what is left in the bottle, and dissolve some more air into the wine. The inert gas will not keep the wine for prolonged periods, but it works well for several days.

Inert gas systems – commercial

These use an inert gas to force wine out of the bottle, and through a nozzle into a glass. No extra air is introduced into the bottle. Enomatic is the market leader, and their website provides more details. These systems allow restaurants, wine bars, and shops to sell wine by the glass, even if it takes weeks to empty the bottle.

Plastic film on top of the wine

A company called Wine Shield sells specially designed thin plastic film, which sits on top of the wine in a bottle. This aims to keep air away from the wine. I haven’t tried it, but it does sound plausible.

A simple and reliable approach

I pour wine into a smaller bottle, and fill it. Pour with care so as not to introduce too much air. Then stopper it and put it in the fridge. Depending on the wine, this is fine for a couple of days. It lasts longer if you squirt some inert gas above the wine.

Screwcaps versus cork for wine bottles

branded natural cork

natural cork

Natural cork provides a very good seal for a wine bottle, but a screwcap is potentially better still. There are pros and cons for each of them.

Sealing liquids

  • Cork has a unique cellular structure which allows it to be compressed, and then spring back to its original shape. This provides a very good seal to prevent wine from seeping out. It can still seep out if the bottle is overfilled, the cork damaged, or because of poor storage.
  • Screwcaps prevent any wine from seeping out.

    screwcap

    screwcap

Sealing gases

  • Cork. Oxygen can slowly diffuse through the cork into the wine. Some corks are more porous than others, and some have defects; this allows more rapid diffusion of oxygen into the wine, and more rapid ageing.
  • Screwcaps. The original screwcaps allowed almost no oxygen into the wine, and this may cause unpleasant odours to develop. Different seals are now available which allow controlled amounts of oxygen into the bottle.

Contamination

  • Corks can be contaminated with TCA, a very small amount of which makes the wine undrinkable. Refer to this earlier post for details. This is cork’s biggest disadvantage.
  • Screwcaps do not contaminate the wine.

Storage

  • Cork. Bottles have to be stored with the wine in contact with the cork. If not, the cork dries out, and becomes a less effective seal. Rapid temperature fluctuations can cause a cork to move within the bottle neck, which can also cause sealing problems.
  • Bottles sealed with screwcaps do not suffer from these problems.

Long-term ageing

  • Cork has been used as a wine closure for centuries, and there is plenty of evidence that a good wine, with a good cork, stored in a good cellar, ages gracefully.
  • Screwcaps have been around for decades, and there is evidence that some wines age well. However, plenty more trials will be needed over many years, before everyone is convinced.

Conclusion

The scientist in me says that a screwcap with the right seal, is the perfect closure. No bottles will be contaminated, and every bottle in a batch will mature the same way. My heart however, would rather see a cork pulled from a fine bottle of wine, rather than someone crack open a screwcap.

What to drink with your fish and shellfish

Seafood and wine the perfect match

Enjoying wine with seafood

The first rule of wine and food pairing, is to drink something you enjoy. The perfect pairing is in the eye of the beholder.

Certain types of wine can be excluded because they clash with fish and shellfish, but a wide range of wines go very well. Heavier styles of wine match better with richer dishes.

Wines to avoid
Avoid tannic grape varieties such as Cabernet Sauvignon and Nebbiolo. Tannins cause puckering and drying of the mouth, and they react with iodine in marine fish and shellfish to produce a metallic taste. This spoils the food and the wine.

Red wines which can work
Some red grape varieties have low tannin levels, and some wines are made in a way which extracts little tannin from the grapes. Good acidity also helps to match with shellfish, and to cut through rich sauces. Some red wines which do work:-

  • Beaujolais. Made from Gamay grapes, and most have low tannin levels.
  • Pinot Noir. Particularly lighter styles of Burgundy.
  • Rioja. Lighter styles made for early drinking work well.
  • Cabernet Franc. The main source is the Loire in France.

White wines
A whole swathe of dry white wines with good acidity go really well with shellfish. Here are some suggestions:-

  • Riesling. A great grape variety, but choosing Riesling needs care, as styles vary from the bone-dry to the lush, rich and sweet.
  • Chardonnay. A racy Chablis for the shellfish. An oaked wine for the rich sauces.
  • Sauvignon Blanc. Whichever style you enjoy.
  • Albariño. A grape variety grown near Spain’s Atlantic coast. It is just made to go with the local fish and shellfish.
  • Picpoul de Pinet. From the Mediterranean coast of France – just right for the local seafood.

Rosé wines
Rosé wines come in a wide variety of styles. Match them in the same way you would white wines.

Sparkling wines, and the dry styles of sherry go well too.

The choice is your’s, but do try unfamiliar wines, as there is always a better one around the corner.

Why does a wine need acidity?

A wine which doesn’t have enough acidity is flabby and boring.

What is acid?
It is one of the five primary tastes – sweet, sour (acid), bitter, salt and umami (savoury). An example of an acid is citric acid in lemons. These tastes are detected by tastebuds, which are located mainly on the tongue, but also in other parts of the mouth.

acid and sugar in grape berries

How acid and sugar levels vary as a grape grows

How acid levels change as a grape berry grows
The diagram above shows that acid levels increase as a grape berry grows, but only to a point. Véraison is the moment when a grape berry changes, and starts to ripen; it softens, changes colour, sugar levels rise, and acid levels fall. Unripe grapes are hard and acidic, with little sugar. Over-ripe grapes are sweet and bland.

Which acids are present in wine?
Tartaric is the main acid, and its level stays fairly steady during ripening. Malic acid is the other significant acid, and this decreases after véraison.

Examples of two contrasting types of wine:-

  • Champagne – the grapes are picked with high acidity, and quite low sugar levels. In most wine regions the grapes would be considered under-ripe. At the end of production, sugar is usually added to take the edge off the acidity.
  • High alcohol Cabernet Sauvignon – these come from hot climates, where the grapes are picked very ripe, with high sugar levels and relatively low acidity. This sugar produces a wine with plenty of alcohol, and acid may be added to make the wine more palatable.

How can you tell how much acid is in a wine?
Unfortunately, very few wine labels provide this information, but the winemaker’s website often does. Acidity is usually stated as pH. I won’t bore you with a chemist’s definition, but pH is a scale in which water is neutral at level 7. The lower the number, the more acidic a liquid is, and wine is usually 3 to 3.5.

A balancing act
Acidity is particularly important in sweet wines, to ensure they are not bland. Sugar masks the acidity, so it may not be obvious, but all good sweet wines have it.

What is meant by a corked bottle of wine?

selection of natural corks

Bleached and unbleached natural corks

A ‘corked’ wine has a mouldy taste and smell. This is caused by chemicals leached from the cork, and is nothing to do with bits of cork floating in the wine.

Where does natural cork come from?

Natural cork is made from the bark of the Quercus suber oak tree, and Portugal is by far the largest producer. The bark is stripped from the tree, and this particular species is able to regrow its bark. Individual corks are then punched out from the bark. Various treatments are carried out along the way.

Origin of cork taint

The main culprit is a chemical called TCA, 2,4,6-trichloroanisole to be precise, although other similar compounds are also responsible. There are several possible sources of these compounds, and they involve fungi, microbes and chlorine treatments, either of the cork oaks, or the punched corks themselves.

How bad is the problem?

There was a time when the percentage of ‘corked’ bottles was estimated at between 2 and 6%. I would say that the incidence has decreased, but the problem has not been eradicated.

What are the cork producers doing about it?

There are two general approaches:-

  • Change the sterilising treatment – in the past hypochlorite bleaches were used to kill off microbes in the cork. Now they use peroxides, or microwave treatments to remove unwanted life in the corks.
  • Use of high tech analytical equipment, such as mass spectrometers and gas chromatographs. These can detect extremely low levels of contamination.

What are winemakers doing about it?

Apart from changing away from natural cork, the best a winemaker can do is to buy top quality corks. Samples from a batch can be tested by immersing them in wine, to see if there is any contamination.

Threshold levels of taste and smell

The threshold level is the minimum concentration at which a person can detect a smell or taste. TCA can be detected at incredibly low levels of a few parts per trillion (yes, a million-millionth). There are two interesting observations:-

  • Some people are far more sensitive to cork taint than others – they have a much lower threshold level. So that one person thinks a wine is just fine, and another that it is undrinkable.
  • The threshold level increases rapidly as the alcohol content increases. Which is why cork taint is very rare with bottles of spirit.

Can cork taint be completely removed by changing to screwcaps or plastic corks?

The answer is no, but the incidence will be much lower. TCA can contaminate other wooden objects in a winery, particularly oak barrels. So some contamination is always possible.