Spice mill and secrets
Angostura is incredibly secretive about the process for creating their aromatic bitters—only 5 people in the world know the full recipe. To keep things secret at the factory, their botanicals and spices are sourced from all over the world and then shipped via London, where they are repackaged into indistinguishable, numbered containers. The blend is prepared in a strictly off-limits room called "the sanctuary" by one of the bitters cognoscenti, and transferred through a chute to this enormous mill, where it is ground to a fine consistency.
The ground spice mixture is sifted through an enormous sieve to remove any small particles which might get over-extracted during steeping.
The spices are then loaded into cylindrical canisters which are placed on top of one of several tanks filled with 190 proof sugar-based distillate. The distillate gets cold percolated through the spice mixture for at least 8 hours to extract the right amount of flavoring. The exacting timing is, of course, a secret.
That's a Lot of Bitters
Once the bitters have mellowed, they get bottled and shipped all around the world—Angostura currently distributes to 165 countries. Think how many little bitters bottles are in this shot... Each tank holds around 45,500 liters!
Start with the sweet stuff
The rum starts with high quality molasses. There's currently a dearth of acceptable quality molasses produced in Trinidad and Tobago, so Angostura sources its sweet, sticky goop from the Dominican Republic, Mexico, Guyana, and as far away as Senegal and Fiji.
Angostura uses one proprietary strain of yeast to take care of fermentation duty, and they add ammonium sulfate to help increase efficiency. With these techniques, they're able to get to 8% ABV in about 36 to 48 hours.
Take a rest, rum!
Here the White Oak, Angostura's premium unaged rum, rests in giant steel tuns for a few weeks to settle before getting bottled and shipped off to market. However, things aren't so quick for the rest of the family...
Putting barrels together
Angostura ages most of its rum in used bourbon barrels. For ease of transport, the barrels are disassembled before shipping, which means they need to get put back together after arrival. Here a master cooper straightens the hoops before reassembling the staves. Since every cask is unique, and some change size and shape during shipping, he's a full time 3D puzzle solver.
Angostura has several rickhouses, but they all share similar features—most importantly, the precise climate control aided by insulated roofs and hollow brick walls and floors. The spirit typically enters into the barrels around 55-60% ABV and comes out only a few percentage lower, even after many years of aging.
Master Distiller John Georges is then able to select and blend different barrels to create the final offerings.