The process now used worldwide in the production of barrique barrels was allegedly "invented" by chance in France. Wine producers near the sea (also) used herring barrels from fishermen and tried to remove the undesirable fish odour in the wood by brushing or planing it out. When this did not lead to a satisfactory result, the barrels were burnt out on the inside. Today, this is known as toasting or barrel branding of the inner barrel walls of barrique barrels. As a rule, the two barrel bottoms are usually not toasted, as this is very time-consuming. However, this also depends on the barrique manufacturer or the customer's (winemaker's) wishes.
Toasting takes place, for example, over an open oak fire, using a gas burner or, more recently, with infrared heat. This achieves a heat of 200 to 250 °Celsius. The duration and intensity of the fire determine the degree of toasting: 10 to 15 minutes for wines, 15 to 20 minutes for spirits(cognac, rum, whisky, etc.). A very strong toasting causes charring and is therefore referred to as charring. The wood is...
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Egon Mark
Diplom-Sommelier, Weinakademiker und Weinberater, Volders (Österreich)