Seasame oil probably has the oldest origins - it was used by the Egyptians. The ancient Greeks used olive oil: in Athens the olive was a sacred tree, symbol of the city's life. Oil was used not only for food but also as a fule to provide light (its use as a fule continued for many centuries in europe).
Vegetable oils, low in cholesterol, balance animal fats in the diet. Oils extracted from a single vegetable species are known as "pure", whereas the label "vegetable" indicates that there are a mixture. most oils sold in shops have been refined, with the result that their original flavour and smell have been removed leaving them quite neutral. However, it is still possible to find unrefined oils which have been obtained by cold pressing; these are termed "virgin" or "natural" oils and they retain the taste of their vegetable origin (olive oil, for example).
Solid oils are vegetable oils which solidfy at normal room temperatures: examples are coconut oil and palm oil.
Uses Oils, sometimes mixed with butter, provide the fatty element in cooking (for deep and shallow frying and browning); they are an ingredient for cold dressings (such as vinaigrette) and of sauces and condiments (mayonnaise, brandade, aïoli, etc.) and they will preserve foods (particularly fish but also goat's cheese and culinary herbs). Finally, they are used in marinades for meat, game and fish.
In general, a distinction is made between oils used for frying and seasoning (in which the linolenic acid content must be lower than 2%) and oils used for seasoning only (particularly soya bean (soy bean) and rapeseed oil). Linolenic acid should not be confused with linoleic acid: the former is a harmful foul smelling substance released when oil is heated above 482°F; linoleic acid, the indispensable vitamin F, is present chiefly in sunflower, soya bean, maize (corn), grapeseed and walnut oils.
Groundnut (peanut) and refined olive oils are the most suitable for heating to high temperatures, though the critical point must not be exceeded: this is reached when the oil begins to smoke. It is best not to heat the same batch of oil to 347°F mare than ten times.
Other oils that should be mentioned are safflower and seasame oils, which are widely used in the East and in Asia; sweet almond oil, which is used in confectionery and pastry making; and beechnut and hazelnut oil, which are not widely used.
Paraffin oil, recommended as a seasoning in some diets and also used to thinly coat dried fruit to prevent sticking, must never be heated: it is a hydrocarbon and not a vegetable oil. If taken in quantity, it can act as a laxative.
In 1862 Pasteur discovered that acetification was caused by a bacterium. Acetification takes place on contact with air; it gives a good vinegar if the wine - red or white - is light, acid and thoroughly strained to get rid of any residue. The operation takes place at a temperature of 68 to 86°F. The fermentation is caused by bacteria pressent in an even velvety grey film, which forms on the surface and slowly sinks into the liquid in a folded sticky mass; this is the vinegar mother (mère de vinaigre). The quality of the vinegar always depends on the quality of the wine or other alcohol used to make it; it must contain at least 6% acetic acid and be clear, transperent and colourless if it comes from white wine or differing shades of pink if it comes from red wine. Spirit or wine vinegars are mostly used in France, but in Britian and North America malt and cider vinegars are also widely used and vinegar may also be made from champagne or even honey. There are also differently flavoured or coloured vinegars (e.g. using beetroot (red beet) or caramel).
Uses of vinegar Essential in the preparation of mustards, cold sauces and vinaigrettes (in which it is sometimes replaced by, or mixed with, lemon juice), vinegar also plays a major roll in cooked reduced sauces and in deglazing. It is indispensable for sweet and sour preparations and for marinades and conserves (pickles, fruit and vegetable chutneys, etc.).
Different types of vinegar have different uses. Spirit vinegar is used to clean fish and mushrooms; it is also used to prepare cocktail onions and gherkins. White wine vinegar is suitable for seasoning endive, cos (romain) lettuce and chicory, for meat, game and fish marinades, to prepare beurre blanc (white butter sauce) and hollandaise and béarnaise sauces and to finish noisette butter, as well as for deglazing. The traditional French white wine vinegar is prefered for making aromatized vinegar at home.
Red wine vinegar is preferable for seasoning delicate or rather flavourless salads (e.g. lettuce), as it has a more pronounced taste. It is used to cook red cabbage and a trickle of this pink vinegar also improves fried calf's liver, sanguette, red meat dishes, pepper sauces, or even eggs sur le plat.
Cider vinegar, like white wine vinegar, is used with fish and shellfish court bouillons; it is also used for chicken in vinegar, dressings and even in stewed apples. Malt vinegars are often prefered for marinated mackerel or herring, chutneys and salads in which fruits and vegetables are mixed (sweet corn, grapefruit, apples, walnuts, etc.).
Home-made vinegar The method consists of pouring some good quality white or red wine into a cask and placing delicatly on the surface a piece of vinegar mother; the vessel is then sealed with a paper stopper (to allow air to pass) and left at room temperature for a minimum of one month and a maximum of two. The vinegar may then be drawn off as required and replaced by an equal quantity of wine. If a vinegar mother is unobtainable, wine vinegar should be mixed with red wine in equal proportions (or cider vinegar with non-pasteurized cider) and then left, as before, for acetification to take place; in this case, however, it will take at least three to four months for the vinegar to be produced. The vinegar mother should always stay on the surface, without mixing with the alcohol. The cask should never be placed in a wine cellar.