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During the fermentation of beers, wines and other alcohol product chemicals
such as Hydrogen Sulfide (H2S) which has been known to plague winemakers for centuries, but it needed in the process. H2S causes are as simple as is its cure, if dealt with soon enough after detection.
There are three primary causes:
- Residual sulfur on the grapes as the result of a late spray for powdery mildew;
- Some yeasts, such as Montrachet(UCD 522) and some strains of Steinberg, are known to produce higher levels of H2S; and more commonly,
- Low nitrogen levels in the grapes which results in higher levels of H2S being produced by yeast cells (all yeasts produce some H2S that is dissipated during fermentation).
Early detection of the rotten egg odor and subsequent racking with deliberate
splashing will usually cure the problem, as H2S is highly volatile. Hydrogen
Sulfide can build up and cause the product to become unsafe.
Our system can detect the trace of Hydrogen Sulfide. It would alert the user(s) of the levels that may be in the barrel. Once the level of H2S goes pasted the predetermined level the user is give the red signal that the levels are pasted their expectations. This would allow the user to correct the levels of H2S to ensure their product wouldn’t go to waste.
During the primary fermentation, the yeast cells feed on the sugars in the must and multiply, producing carbon dioxide gas and alcohol. The temperature during the fermentation affects both the taste of the end product, as well as the speed of the fermentation. For red wines, the temperature is typically 22 to 25 °C, and for white wines 15 to 18 °C. For every gram of sugar that is converted, about half a gram of alcohol is produced, so to achieve a 12% alcohol concentration, the must should contain about 24% sugars. The sugar percentage of the must is calculated from the measured density, the must weight, with the help of a saccharometer. If the sugar content of the grapes is too low to obtain the desired alcohol percentage, sugar can be added (chaptalization). In commercial winemaking, chaptalization is subject to local regulations.
During or after the alcoholic fermentation, malolactic fermentation can also take place, during which specific strains of bacteria convert malic acid into the milder lactic acid. This fermentation is often initiated by inoculation with desired bacteria.
Keep it at a cool
constant temperature
What Temperature?
The magic temperature to store wines is between 12-16 degrees Centigrade. However, any temperature between 5-18C (40-65F) will do as long as it remains constant.
A very important point of this guide is for you to understand the importance
of storing your wines at a constant temperature all the time.
The degree and the speed of the temperature change is critical. A gradual change between summer and winter of a few degrees won’t matter. The same change each day will harm your wines by ageing them more rapidly (not in a nice way).
The most important rule when storing wine is to avoid large temperature changes or fluctuations. You’ll notice damage of this nature straight away from the sticky deposit that often forms around the capsule. Over time the continual expansion and contraction of the wine will damage the ‘integrity’ of the cork. It’s like having the cork pulled in and out again every day. When this happens, minute quantities of wine may be pushed out along the edge of the cork (between the cork and the bottle neck) allowing air to seep back in. Once the air is in contact with your wine the irreversible process of oxidation has begun and your wine is ruined.
A quick way to check for this is to remove the capsule. Do not do this if you are
keeping the wine for investment purposes as this harms the appearance and thus the value of the wine. Do this only if you are interested in keeping great drinking wines in your own cellar.
Even a steady storage temperature of 21C (70F) is better than temperature that goes from 7C to 18C (45F - 65F) and back again every day. At 12-16C the wine will age properly enabling it to fully develop. Higher temperatures will age wine more rapidly and cooler temperatures will slow down the ageing process. Heat will generally speed up any chemical reaction and this is all that is going on in the bottle, a slow controlled chemical reaction that improves your wines. That doesn’t mean you can keep your wines in the oven for a week and end up with fantastic wines. Just the opposite. Irreversible damage is done if your wine is kept at over 28C (82F) for even a month. At 12°C (55°F) wines will age so slowly and develop such fantastic complexity that you will never have to worry about them. And note that white wines are affected far more by temperature than red wines. Cold stabilization is part of the white wine winemaking process. The wine is chilled to minus 4C (25F) for a few days. This precipitates out the impurities in the wine. You may have noticed small crystals or grains in the bottom of a white wine you’ve had in the fridge for a while. This is due to the wine not being cold stabilized during the wine making process. Not necessarily a fault, just a part of the winemaking process. Don't store a bottle of sparkling wine (Champagne in some parts of the world) in your fridge for that special day. When that day arrives there may not be much to celebrate with. Keep the bubbly in the fridge for a day or two but no longer. After that and you should take it out of the fridge and put it back in your cellar.
What can you see and taste in a temperature damaged wine?
One dead giveaway of heat damage is color. A brick red brown color, especially in a young wine can be an indicator of oxidation damage due to heat. Since Sherry is an oxidized wine, another indicator of heat damage in wines is a sherry-like taste.
Wine Serving Temperature Guidelines
Temp F Temp C Notes
100° 39° Warm Bath
68° 20° -
66° 19° Vintage Port
64° 18° Shiraz and other red wines
63° 17° Red Burgundy, Cabernet
61° 16° Pinot Noir
59° 15° Chianti, Zinfandel
57° 14° Tawny/NV Port, Madeira
55° 13° Ideal storage for all wines
54° 12° Beaujolais, rose
52° 11° Sauternes
50° 10° Most white wines
48° 9° Chardonnay
47° 8° Riesling
45° 7° Champagne
43° 6° Ice Wines
Summary: Store your wines between 12-16 degrees Centigrade and make sure the temperature stays constant
Humidity
The wrong humidity level is another enemy of the natural cork seal. A natural cork is compressed and forced into the bottle as a 100% natural seal. The resilient and elastic cork now wants to expand and is continuously pushing out against the glass to form a seal.
The air space between the bottom of the cork and the wine is called the ullage. The ullage will increase over time as the cork is far from a perfect seal. It will let some air in while also absorbing some wine. Low humidity combined with a defective cork results in the wine moving out of the bottle (increasing ullage) and air naturally moving into the bottle.
The lower the humidity and the worse the cork, the faster this will happen to your precious wine. Once the air is in it’s not long before your wines starts turning into vinegar.
Moderate humidity is important to keep the cork in good resilient condition and prevent it from shrinking. A relative humidity of 50-80% is an acceptable range with about 70% recommended. A standard commercial refrigeration or air conditioning system is programmed to run at about 20% humidity. Low humidity will cause the cork to dry out and lose its elasticity and allow air to get into the bottle. This will happen even if the bottles are stored on its side.
A very easy way to increase the humidity in a confined space is to leave out a bucket of water. This will naturally evaporate and raise the humidity. Excessive humidity will not harm the wine but will cause the labels and any other paper products like cardboard boxes to rot. And if you are keeping the wine to drink for yourself this may be OK. But remember that any damage to the label and presentation of the bottle will lessen it’s investment value.
Summary: Anywhere between 50-80% relative humidity is acceptable, 70% being ideal
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