Hygiene In Wine Making

The greatest care should be taken to ensure that all the equipment and ingredients used are clean and free from spoilage organisms of whatever kind. Much of the equipment used, such as casks, jars, bins, buckets, funnels, wooden spoons, corks, bungs, and so on, afford hiding places for fungi or bacteria. Indeed, put away damp in a dark place and there is soon a visible mould growth upon them. Unless sterilised, such equipment could rapidly spoil a new wine.

It is most important then, that all winemaking equipment be put away clean and dry after each using, and that it be freshly sterilised before each subsequent use. This applies especially to bottles, pressing cloths or bags and corks.

The most common spoilage organism is mycoderma aceti, sometimes called ‘aceto-bacter’. This is the vinegar bug which causes wine to smell and taste of acetic acid — the main constituent of vinegar. The bacteria is frequently carried by the little fruit fly — drosophila melanogaster. It alights on ingredients and equipment, leaving behind enough bacteria to begin a colony. But there are many similar organisms, including wild and unwanted yeasts and the large family of lactic acid bacteria, all of which cause an unpleasant smell in the bouquet and a bad flavour in the wine. These organisms like access to oxygen and dislike sulphur.

Sulphur has long been known for its purifying qualities. Before simpler ways were known, a sulphur candle was burned inside a cask to purify it. It took many years of research before sulphur could be prepared in such a way as to be safe for use in the human body but eventually the answer was found in sulphonamide. Amateur winemakers have a safe access to the anti-toxic qualities of sulphur in the crystals of sodium or potassium metabisulphite, both of which are equally suitable. Winemakers refer to them simply as sulphite. They are available as loose white crystals or in tablet form marketed under the name of Campden tablets. One tablet dissolved in a gallon of water releases 50 parts per million of the gas sulphur dioxide which is the anti-toxic element. If crystals are bought loose, 450 grams (1 lb) dissolved in 4.5 litres (1 gallon) produces a solution of which two 5 ml spoonsful are equivalent to 1 tablet. This is, of course, the cheapest way of buying and using sulphite. For most people 100 grams of sulphite dissolved in 1 litre of water is an ample quantity. If kept well-stoppered and stored in a cool place it will keep for several months. The effect of sulphite is enhanced in an acid solution. Always add, therefore, 10 grams

 of citric acid cystals per 100 grams sulphite crystals.

Normally 50 parts per million is sufficient sulphur dioxide to purify clean equipment or a clean must. Dirtier equipment or some damaged fruit need double this quantity, ie two tablets or four 5 ml spoonsful of standard solution. Before using any equipment it should be rinsed in this solution. Corks should be soaked for half an hour in it, larger equipment should be washed over in it. Bottles when washed and ready for use should be sterilised by pouring a sulphite solution from one bottle to another and leaving them to drain. Do not subsequently wet them again.

Sulphite has a further advantage for the wine-maker in that it is an anti-oxidant, ie it prevents oxidation. When preparing fruit, the appropriate quantity of water together with sufficient sulphite to produce a 50 parts per million solution for first class fruit and 100 parts per million for second class fruit, together with a few grams of citric acid, should first be placed in a mashing bin. As the fruit is crushed or cut to remove stones, it should be dropped into the bin. In this way, browning (which is oxidation) will be prevented. The quality of the resulting wine will then be enhanced and there will be no taint of oxidation.

Because the sulphur dioxide gas given off by the sulphite in a must is toxic to all micro-organisms, wine yeast should not be added until 24 hours after the sulphite. In this way the sulphite has time to kill all the micro-organisms and prepare a clean must in which the active yeast can begin fermentation with¬out competition, so to speak. The small amount of sulphur dioxide left in the must after 24 hours does not inhibit the true wine yeast.

If a sulphite solution is used regularly in the winery for sterilising all equipment and ingredients, for wiping over surfaces and floors, problems of infection by spoilage organisms can be eliminated. But all equipment means ALL equipment and small items such as a funnel, an hydrometer, a thermometer, a siphon, a filter or a spoon should not be over-looked. Similarly with ingredients. Dried fruit should always be washed in a sulphite solution of 100 parts per million and then you can be sure that you are starting your must off in a clean and hygienic condition. Sulphite is the winemaker’s best friend. It is not as well appreciated as it deserves.

For both the beginner and the experienced wine-maker the keeping of records is most important. It is so easy to forget whether this ingredient or that was included and, if so, how much; to remember specific gravity readings and dates; to remember even, the base ingredients. When mature, all white wines look similar and do not necessarily taste of their main ingredient; and the same applies to red.