The latest Experimental Collection release from Buffalo Trace Distillery involves the sour mash process.  Just about all bourbon is made using sour mash.  Basically, once the mash is cooked, some setback (previously distilled mash) is quickly added to “sour” the mash before yeast is added for fermentation.  It helps control PH levels during fermentation, which affects the final flavor of the whiskey.  It also helps achieve consistency between batches.

What Buffalo Trace has done here is slightly different.  According to their press release, the mash was “cooked and cooled to standard; however, the similarities stop there. The mash was allowed “to sour” before yeast was added to start the fermentation process, a method long abandoned due to its more laborious process.”

These particular whiskies were distilled in 2002 and entered barrels at two different entry proofs – 105 and 125.  They were aged for 13 years on the seventh floor of Warehouse I.  Barrel entry proof also affects how the final bourbon turns out.

105 Entry Proof

The lighter nose of the two, the 105 Entry proof carries a large vanilla note.  I also get light caramel and cherries.  All the aromas here seem to be separated and easily picked out.  The official tasting notes mention vanilla and fruit for the palate.  That fruit to me is cherry.  Those two notes really dominate the palate.  There’s a hint of oak and little brown sugar.  The finish turns a bit dry.

125 Entry Proof

The nose here is a bit more traditional – caramel, vanilla, spice, and oak.  A caramelized cherry note is also present.  The aromas here seem more compact or concentrated compared to the 105 Entry Proof expression.  There is a bit more body here, maybe even oilier.  Oak spiciness shines here, along with fruit and light burnt sugar.  The finish isn’t as dry as in the 105, and comes across as sweet.

Buffalo Trace Experimental Collection releases are always interesting, and this Sour Mash experiment is no different.  The fun comes in comparing and contrasting the two sibling releases.  Both are superb whiskies, and I recommend picking both up to experience how different entry proofs will yield different whiskies.