$$ — 50% ABV — ~10 years
The big complication that distillers rarely talk about is yeast, the living powder that makes alcohol possible. So valuable is this little microbe that all the big companies keep backups in special yeast banks that dot the globe; if the distillery goes up in flames (as Heaven Hill's did in 1996) their yeast would be recoverable.
Without their proprietary yeast, a distiller could not hope to create the same-tasting liquor they've come to be known for. Yeast contamination is so possible and so scary as to ward off most distillers from experimenting with it in any way, even Buffalo Trace.
And then there's Four Roses. With five proprietary yeasts, this Kentucky distiller is constantly experimenting with how fermentation changes the flavor of their Bourbons. But even Four Roses seems to have honed in on a favorite: their Single Barrel expression, possibly the best bang for your buck on the whisky market today, uses only their "V" yeast, which creates a creamy caramel taste. Aged for about ten years and proofed at a full hundred, this is a gorgeous and slightly dry Bourbon that works well however you like it (old fasioned for me, thank you).
The distillery's Small Batch is less expensive and is a blend of Bourbons made with the spicy "K" and fruity "O" yeasts, which lend to each other well, but are best in a cocktail. The floral "Q" and herbal "F" are the wildcards, often dumped into the cheap Yellow Label. But sometimes, the distillery will offer special releases, like the 2014 single barrel release which featured "F." It's for this reason, adventurous Bourbon lovers often look to Four Roses.
vanilla, toffee, deep, dry, cherry, maple, molasses, roses