Fino ("refined" in Spanish) is the driest and palest of the traditional varieties of sherry and Montilla-Moriles fortified wine. They are consumed comparatively young and, unlike the sweeter varieties, should be consumed soon after the bottle is opened as exposure to air can cause them to lose their flavour within hours. Flor The defining component of Fino sherries is the strain of yeast known as flor that floats in a layer on top of sherry in the wine barrel. Until the mid-19th century most sherry winemakers did not understand what this yellowish foam that randomly appeared in some of their barrels was. They would mark these barrels as "sick" and relegate them to their lowest bottlings of wine. It turned out that this strain of Saccharomyces yeast thrived in air, and the more "head room" there was in the barrel the more likely it was to develop. Over time winemakers noticed that these wines were lighter and fresher than their other sherries, with the flor acting as a protective blanket over the wine that shielded it from excessive oxidation. Varieties Jerez Fino, made from grapes grown in the vineyards around Jerez and aged in the wine cellars there, where the climate is hotter than those near the coast. The hotter summers cause Jerez Fino to develop a thinner layer of flor and thus a stronger flavour due to more exposure to the air. Puerto Fino, made around El Puerto de Santa María. The cooler climate near the sea results in a thicker layer of flor and a more acidic and delicate flavour than Jerez Fino. Manzanilla, made around Sanlúcar de Barrameda, where the climate is cooler than El Puerto de Santa María. Similar to the Puerto Fino, Manzanilla has a fresher and more delicate flavour than Jerez Fino. Fino may also be produced in DO Montilla-Moriles. There the Fino along with the other sweet and fortified wines is made from the Pedro Ximénez grape as opposed to the Palomino grape used in Jerez. Sweetened Fino is called Pale Cream Sherry. On 12 April 2012, the rules applicable to the sweet and fortified Denominations of Origen Montilla-Moriles and Jerez-Xérès-Sherry were changed. The classification by sweetness is: Production In production of finos, winemakers normally will only use the free run juice; the juice that is produced by crushing the grapes under their own weight before they are sent to a wine press.