February 02, 2001 -- Bentonite is a fining agent. Fining is the action of removing particles that make a haze in wine by combining them with materials that bind to them and force them out of suspension, leaving the wine clear and bright. It not only improves a wine?s appearance; it also makes sure that it is stable. Stable means that it won?t change if appearance, taste, aroma, or chemical composition while in storage. Bentonite is a type of clay, known as aluminosilicate. Its technical name is Montmorillonite. It?s found with various minerals attached to it, such as sodium, calcium and magnesium. It was originally found in Fort Benton, Wyoming (where the name came from). It?s used in winemaking, beauty treatments, mineral extraction, water treatment, and kitty litter. When used in winemaking, it is stirred into the wine to remove proteins and other haze causing particles. It works through adsorption. This means that it attaches itself to a particle, and together they are too heavy to stay in suspension, falling to the bottom of the carboy, leaving the wine clear and stable. Bentonite settles out so completely that it does not leave any residue of taste or colour behind. Some wine kit companies (like Brew King) add their bentonite on the first day, and some add it after fermentation. This is one of the fundamental differences between kits that you may have noticed. The reasons behind it go beyond technology, straight into winemaking philosophy. When bentonite is added on the first day, it disperses through the wine and most settles to the bottom within a few hours. At the end of 48 hours, however, the bentonite is back in circulation. This is because of the process of gas nucleation that the CO2 in the wine is undergoing. As the yeast ferments the sugar, it converts it into carbon dioxide (CO2) and alcohol. The bubbles of gas don?t actually appear out of nowhere: they want to come out of suspension on some kind of a point, where a nucleus of gas can form the beginning of a bubble. Thus we get the term ?nucleation?. This point could be a scratch in the carboy, a bit of grape material, or a particle of bentonite. The bentonite is surrounded by a bubble of gas and floats up to the surface of the wine. When the bubble bursts, the particle of bentonite drops back down to the bottom of the carboy, all the time working to adsorb the other particles clouding the wine. In this way, the bentonite is circulated around the wine continuously for days, doing its job. When bentonite is added to a wine kit post-fermentation, it does not have the advantage of the CO2 lift that it would get during fermentation. Therefore the winemaker is obligated to stir it through the wine repeatedly, ensuring the thorough dispersal. In addition, because the bentonite will quickly settle out before it can effectively clear the wine, significantly more is needed when used post-fermentation. Brew King kits typically use 10 or 15 grams of bentonite, while some companies use up to 80 grams! Not only does this amount cause the formation of a deep, loose sediment bed; it also has the effect of stripping the wine. Finings are considerably more powerful than most people suspect. With a sufficient dosage of finings it is possible to strip a red wine to the point where it becomes ?white?. Too much finings can lead to a stripping of colour and flavour, making it necessary to formulate much darker and stronger wine kits to compensate. By adding the bentonite on the first day, the formulation can be much closer to the desired finished wine, without extra additions or manipulation. Although it may seem a little odd to be adding clay to your wine, when the finished product is clear and delicious, you?ll be glad that there was a little bentonite to polish it up. Potassium Metabisulphite is a stable source of sulphur dioxide in winemaking. The use of sulphur compounds is not a recent innovation. The great Dutch shipping empire popularised the use of sulphur in the 16th century by refusing to ship any wines not treated. They insisted on sulphites because sulphite treated wines were the only ones that survived a long sea voyage without turning into vinegar. Sulphites work by releasing free sulphur dioxide, which inhibits yeast, mould and bacteria. It does this in two ways: one, it kills some of the organisms outright, and two, it blocks the surviving organisms ability to reproduce. If your winemaking equipment is physically clean and you've rinsed it with a sulphite solution, nothing will grow on it. Sulphites are also added directly to wine after fermentation, to help prevent oxidation. Oxidation in wine follows the same pattern that you see in the cut edge of an apple-the wine turns brown and takes on a flat 'cardboard' taste. Sulphur binds with the oxygen in the wine and prevents this damage. Many people worry that they may be allergic to sulphites. True sulphite allergies are very rare. It's more likely that they have a histamine reaction to red wine, or that they have been over exposed to sulphites in the past. In the 1970's restaurants would douse their salad bars with 2000 PPM (parts per million) sulphite solutions in order to keep the produce fresh. Mixing with food acids, such as dressings or vinegar, would cause the salad to release clouds of sulphite gas, provoking unpleasant reactions. Some facts that might clear up any misunderstanding about sulphites: Sulphites are a recognised food additive. The federal government controls their use. All commercially available wines in the province of British Columbia contain sulphites, even those labelled 'Kosher' or 'Organic. The legally allowable amount is 70 PPM. Nearly all dried fruits and meats contain sulphites. Raisins, for instance, have up to 250 PPM. The amount of sulphite provided in wine kits will result in a level of between 15 and 30 PPM in a finished wine. All grape-based wines produce Sulphites naturally during fermentation, up to a level of about 10-PPM. Even with no addition of outside sulphites, wines will still contain them. This is not to say that sulphites are totally benign. People with asthma or emphysema should avoid inhaling sulphite powder or the gas that comes off the prepared solution. It can act as a bronchial constrictor, aggravating any breathing problems. Also, adding extra sulphites to wine is of no benefit, as it can spoil the flavour, giving it a 'burnt match' smell. It's important to follow directions for sulphite additions. The upshot of sulphite use is this: without sulphites you'd have to be very careful to keep all of your equipment sanitary and you'd still have to drink your wine quickly, before it spoiled, probably within one or two months. Potassium Sorbate: Used For: Prevents renewed fermentation in sweet wines. Inhibits reproduction of mould and yeast. ? g of Sorbate dissolved per litre of wine will prevent spoilage. 5 ml (one Teaspoon) = approximately 2.8 g. Bad Ideas: Must not be added until fermentation has finished. If sorbate is added to a wine during malolactic fermentation, it will be converted to a compound with a strong and disagreeable odour. Hazard classification: Not hazardous. GRAS (Generally Recognised As Safe) by Agriculture Canada. Chitosan is a non-proteinaceous fining agent, a polysaccharide of the Sucrose Polymer family. It is derived from chitin extracted from ocean shellfish, the same organic material that makes up fingernails and human hair. It works by a process of molecular adsorption, where the Chitosan has an electrical charge, which attracts oppositely charged particles clouding the wine, binding them and pulling them out of suspension. It s also used as a food additive and dietary supplement. Although it is derived from shellfish, there is absolutely no danger of any allergic reactions to the product, as there are no allergens left after the Chitosan is processed.