When fining wines to remove harsh tannins, there is a chemical process used. Positively charged additives react with negatively charged particles in the wine and vice versa. Historically, this is how wines were also clarified as the compounds combine and precipitate, leaving the wine cleaner than before fining. The proteins in the wine are positively charged, so to remove them, we add a clay called bentonite. This is negatively charged and combines with the proteins and the combination precipitates. This process uses inorganic clay and doesn’t affect the wines vegetarian or vegan status. We use this process for white and rose’ wines but not for red wines.
With regard to white wines, historically all sorts of fining agents were used to remove tannins and polyphenols which are negatively charged. To remove them, we have added positively charged proteins (amino acids which are by definition of an acid, are positively charged).
White wines first:
In the past we have used milk protein. However, we have stopped this. Today we only PVPP. (Please see definition from Wikipedia below.) In the last paragraph, they mention the use in winemaking and that it replaces a protein in the process. PVPP is a manufactured polymer with the appearance of a white powder. Hence, this makes our white and rose’ wines vegetarian and vegan friendly.
The cross-linked form of PVP is used as a disintegrant (see also excipients) in pharmaceutical tablets.PVPP is a highly cross-linked version of PVP, making it insoluble in water, though it still absorbs water and swells very rapidly generating a swelling force. This property makes it useful as a disintegrant in tablets.
It is also used as a fining to extract impurities (via agglomeration followed by filtration). It is used in winemaking. Using the same principle it is used to remove polyphenols in beer production and thus clear beers with stable foam are produced. One such commercial product is called Polyclar. PVPP forms bonds similar to peptidic bonds in protein (especially, like proline residues) and that is why it can precipitate tanninsthe same way as proteins do.
For the fining of red wines, we only use gelatine. Gelatine is derived from animal derived protein sources. It is the same stuff you add to jelly to make it set. The gelatine is positively charged and reacts with the negatively charged tannins and they precipitate, making the wine softer on the palate. You do the same thing when you add milk to tea or coffee. The protein in the milk (casein) reacts with the tannins in the tea and coffee and the resulting drink is less bitter and astringent.
This is where it becomes interesting and a little grey. We add the gelatine to the wine, but it all reacts and precipitates. The wine is then filtered and the resulting wine has no gelatine in it. There have been extensive experiments carried out by the Australian Wine Research Institute which prove this. So from a vegetarians perspective, if they don’t want to ingest any animal products, it would be ok to drink the wine. It they don’t want to have any animals harmed, then the wine wouldn’t be suitable for vegans for example.
In brief, bottled wine will last more than a year and will not “go off”. Over time, it will develop aged characters and will eventually oxidise and go brown, making it unpleasant, but not dangerous to drink.
There are many factors which affect the ability of white wines to age. The sulphur dioxide levels (acts as an antioxidant) at bottling, the dissolved oxygen levels at bottling (dictates risk of oxidation from within), the oxygen permeability of the packaging material (dictates the risk of oxidation from without), the wines pH (determines the effectiveness of the sulphur dioxide to act as an antioxidant) and the temperature of the wine during storage (affects the rate of oxidation).
Bag in box wine has a high risk of oxidation due to the large surface area of the container where oxygen can get in, that is through the plastic. Assuming the wine is bottled in good condition, you could assume that this wine has a shelf life of about 9 months.
For bottled wine, if the wine is bottled in good condition with a low dissolved oxygen level, the wine can last for several years and in many cases will continue to improve with age.
Our wines are bottled with moderate sulphur dioxide levels, relatively low pH, low dissolved oxygen levels and are sealed with Sarintin lined screw caps (very low oxygen permeability and low surface area), resulting in an ability to age for several years.
However, many people prefer to drink white wine as a “fresh” product. During the bottle ageing process, the wine will lose freshness and primary fruit characters and “bottle age” characters will develop which are more toasty in nature.
The wine is still safe to drink as it is sterile filtered and therefore no micro organisms will be present. At normal wine pH and alcohol levels, no human pathogens can grow in wine.
If product is stored at high temperatures, i.e. above 25C for an extended period of time, the wine quality and freshness will be reduced. High temperature (for example if left in a car on a hot day) will reduce wine quality rapidly.
So if you buy our wine and store it in a cool, dark, dry place, you will be safe to keep it for well over 12 months, assuming you are comfortable with the wine slowly developing aged characters.