Ron Zacapa Rums are made from sugar cane harvested in southern Guatemala, which is pressed into virgin sugar cane honey, a process unique to the Guatemalan style of rum production. This liquid is then fermented, distilled and taken to the mountains for aging, where the flavor of the rums is further refined through the premium aging process known as Sistema Solera.
The Ron Zacapa Centenario XO is blended from these solera aged stocks which range in age from 6 years to 25 years. These stocks were aged in special cellars more than 7000 feet above sea level. The solera barrels are a mixture of reused American Bourbon, Sherry, Pedro Ximenez wines, and Cognac barrels. The combination of solera aging and the wide variety of reused barrels creates a highly complex rum with a rich aroma and flavour.
Here is a link to the review of the #20 spirit on my Rum Howler Top 100 Spirits Countdown of the best spirits I have ever tasted.
#20 – Ron Zacapa XO (25 Year Solero) Rum
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You may follow my Countdown list of the 100 Best Spirits here: The Rum Howler 2015 – Top 100 Spirits
This is a true Solera rum with 4 rows of aging barrels set one atop each other. As the rum ages, a portion of the rum moves through each row until it reaches the final solera row at the bottom years later. The barrels are not emptied fully and only a portion of the rum from the previous or higher row is moved to the lower row each time. According to the Santa Theresa website, a very small portion of the rum reaches an age approximating 25 years before bottling.
The Rum Howler Blog 