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Although wine vinegar has traditionally been used, nowadays you can find numerous varieties in the shops, including everything from flavoured ones to balsamic ones. This sour tasting preservative is the product of two fermentations. An initial in which yeast converts the sugar into alcohol and creates a liquid with an alcohol content of between 6% and 9%. During a second fermentation, an aerobic bacteria called Acetobacter Aceti acts on the ethyl alcohol and produces acetic acid, thus creating vinegar.  

Until the start of the nineteenth century, it was just obtained by the spontaneous acidification of wine which went sour in the barrels, but as time went by different methods were devised for making it, some being slow and laborious but which produce high quality vinegars. All vinegars require maceration time, preferably in wood, which can last between six months to several years, as is the case of traditional balsamic vinegars from Modena. It is then filtered and clarified. The process ends with pasteurisation. 

Unmistakable touch
Of Arab origin, vinegar has always been a fundamental ingredient in pickling, particularly when preserving game and fish. In Al-Andalus it was consumed diluted with salt water, as this caused it to lose some of its strength and it could be used in numerous dishes. For pickling, it was boiled several times before adding oil and spices. 

Modern cookery also uses vinegar regularly. Mother sauces include vinaigrettes, which are made by pouring vinegar into a bowl, adding oil, salt and pepper and stirring with a hand whisk. If the vinaigrette is mustard based it is recommended that the vinegar be added at the end, after the salt, pepper, mustard and oil. 

Combined with oil and salt it is the basic salad and vegetable dressing and due to its preserving effect it is often used in marinades and pickles. Its flavour gives an unmistakable touch to traditional dishes such as gazpacho or anchovies in vinegar, different types of soup, as well as special sauces. When preparing emulsions from oil, vinegar, salt and pepper, the proportion should be three parts oil for every one of vinegar, dissolving the salt in the vinegar first and then adding the oil. 

Along with wine vinegar, nowadays you can find a wide variety of vinegars flavoured with different herbs, which give a delicious flavour to recipes. These include tarragon vinegar, often used as a sour dressing for salads and meat dishes, rosemary vinegar, suitable for pickling and lamb stews and dill vinegar, often added to fish such as salmon. 

Different types
There are other types of vinegar, which are made differently to the classic product. The one that stands out the most is “acet balsamic”, a speciality which was already used in cooking in Roman times. The most well-known is that from Modena, which has an intense, shiny, dark brown colour, sweet taste and strong aroma, as a result of a long maceration. It is frequently used in game dishes and vinaigrettes but care must be taken when using it due to its acidity, consequently when preparing the ingredients for a recipe, it is recommended to add it last. One spoonful per person is usually enough. It is preferable to use too little than to ruin a good dish. 

On the other hand, when natural cider ferments and the alcohol turns into acetic acid, cider vinegar is obtained, often used in Northern European gastronomy to replace wine vinegar as it contains a lower proportion of acetic acid and is milder on the stomach. Something similar happens with malt vinegar, which is made from malted barley. After it has been distilled it results in a clear liquid containing the same amount of acetic acid, but a milder flavour. 

Cider vinegar is highly suitable for dishes requiring less strength or a fruity flavour, in salads and for making vinaigrettes, as is sherry vinegar, made exclusively from acetic wine fermentation using wine from the Jerez Denomination of Origin. It is one of the most prestigious and has a concentrated flavour, which is stronger than wine vinegar with hints of wood and a dark colour. Outside Spain, Champagne and particularly Oporto vinegars have a good reputation, and are especially good for making vinaigrettes. 

Finally, it is sensible to remember the Italian aphorism “in order to dress a salad you need an expert with salt, a prodigy with oil, a miser with vinegar, a madman to mix it and a desperate man to eat it”.