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Technical

What does the Bentonite that comes in my wine kit do?

Bentonite is added at the start of the wine making process to provide a nucleation site to aid in fermentation. Bentonite also aids in the clearing process by attaching itself to particles in the wine and dragging them to the bottom of the fermentor.

How much sugar would be in a 5oz glass of wine?

In a finished, dry wine, made to the manufacturer’s instructions, there should be 1/2 gram of sugar or 1/6 of a teaspoon in a 200 ml glass. You will also find about 4 grams of carbohydrates and about 100-120 calories. A sweet wine will have higher levels of sugar carbohydrates and calories.

What do the potassium metabisulphite and potassium sorbate do for my wine kit?

It is a common misconception that the potassium metabisulphite and potassium sorbate we add to stabilize our wines actually kills the yeast- they do not. What they do, in conjunction with the fining (clearing) agent, is inhibit the reproduction of spores, moulds, fungi and yeast. In a sense they act as birth control for micro-organisms (including yeast) and prevent the wine from spoiling.

Stabilization is more like a three-phase process. When the potassium metabisulphite is added it knocks the yeast into dormancy, the high alcohol and the low pH level in the wine help this. Now that we have “stunned” the yeast the fining agent drops the yeast out of suspension so it is no longer in contact with the wine. The potassium sorbate coats the yeast cells, preventing the remaining low levels from reproducing to a viable culture level. This is why we are able to add F-Packs and wine conditioner to our wines to sweeten them without the wine re-fermenting.

NOTE: The important thing to remember is to use your hydrometer! Neither sulphite nor sorbate have the ability to kill or reduce yeast populations. If there are any live yeast cells and a source of sugar, no amount of sulphite and sorbate will stop the wine from eventually fermenting out. This is one of the reasons for clearing problems. If you stabilize to soon your yeast will just keep fermenting- although at a sluggish rate, and the fining agent will not be able to drag down the active yeast cells. Using your hydrometer will assure you that your wine has stopped fermenting. A good visual clue that your wine has stopped fermenting is when the wine starts clearing on its own. If the wine has cleared out about a 1/3 of the way on its own it is a good indication that all sugars are used up and the yeast is starting to go dormant. This and the same hydrometer reading for two consecutive days are a great indication that your wine is ready to stabilize.

What is the alcohol content of my wine?

The wine kits we sell have a listed alcohol content that will be achieved by following kit instructions. You can however get an accurate alcohol by volume determination. You will need the starting gravity and the finishing gravity of your wine so make sure you take an original hydrometer reading before you add your yeast and write it down. You will need it to figure out your alcohol content. Take the original gravity and subtract the gravity of the finished wine, and multiply that number by 131. For example, if you started out with a gravity reading of 1.088 and had a finishing gravity of 0.998, the difference between the two would be 0.090. Multiply that by 131 and you get 11.79 or 11.97% alcohol.

eg. 1.088 – 0.998 = 0.090 0.090 x 131 = 11.79 or 11.97% alc

What is oxidation?

The easiest way to think of oxidation is to think of cutting an apple in half. When you cut an apple in half and eat it right away it is flavourful, crisp, sweet and refreshing. If you leave it on you kitchen counter for a few hours it loses its pleasant characteristics and becomes brown in colour, sour, bitter and flavourless. The same thing happens to wine.

When wine oxidizes white wines become brown like apple juice, loses any pleasant bouquet and has a bitter finish on the palate. Red wines also have brown tones but are not as evident as in white wine, however the flavour profile deteriorates the same as a white wine.

What causes oxidation? The obvious answer of course is exposure to oxygen. How do you prevent exposure to oxygen?

There are many ways…

Only rack your wine when your instructions advise.

Minimize splashing while racking your wine.

Make sure you fill your wine bottles to the appropriate level (a Bottle-filler does this automatically and minimises splashing while filling your bottles).

Inserting a proper cork.

Most importantly, only buy wine kits that have a production date code on them (“best before dates” can be deceptive as they do not tell you how old a kit is). Wine kits will deteriorate in the plastic bladder inside the box. A wine kit should be made within a year of its production date or else oxidation can start to take place. Once your wine kit is oxidized your wine will be oxidized.

If you have any questions about any of the wines you have made give Wine Sense a call. We can identify any oxidation problems you might have and help you make a wine that you will be proud to serve your friends.




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