Solera

Solera is a process for aging liquids such as wine, beer, vinegar, and brandy, by fractional blending in such a way that the finished product is a mixture of ages, with the average age gradually increasing as the process continues over many years. The purpose of this labor-intensive process is the maintenance of a reliable style and quality of the beverage over time.Solera means literally "on the ground" in Spanish, and it refers to the lower level of the set of barrels or other containers used in the process; the liquid (traditionally transferred from barrel to barrel, top to bottom, the oldest mixtures being in the barrel right "on the ground"), although the containers in today's process are not necessarily stacked physically in the way that this implies, but merely carefully labeled. Products which are often solera aged include Sherry, Madeira, Lillet, Port wine, Marsala, Mavrodafni, Muscat, and Muscadelle wines; Balsamic, Commandaria, some Vins doux naturels, and Sherry vinegars; Brandy de Jerez; beer; rums; and whiskies. Since the origin of this process is undoubtedly out of the Iberian peninsula, most of the traditional terminology was in Spanish, Portuguese, or Catalan.

In the solera process, a succession of containers are filled with the product over a series of equal aging intervals (usually a year). A group of one or more containers, called scales, criaderas ('nurseries'), or clases are filled for each interval. At the end of the interval after the last scale is filled, the oldest scale in the solera is tapped for part of its content, which is bottled. Then that scale is refilled from the next oldest scale, and that one in succession from the second-oldest, down to the youngest scale, which is refilled with new product. This procedure is repeated at the end of each aging interval. The transferred product mixes with the older product in the next barrel.

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