Ben HoshourApproved on 2026-08-24. This is a distinct retrieval concept with a complete evidence chain and a clear boundary from its parent Topic and operational Process record.
Definition
A fermentation-control practice that incorporates acidic stillage or backset from a previous distillation into a new whiskey mash.
Scope
Use this tag when
- Discussing backset, setback, or spent stillage returned to a new mash.
- Retrieving evidence about mash acidity, pH conditioning, or fermentation consistency created through that reuse.
Do not use this tag when
- The material concerns fermentation generally but does not discuss backset.
- “Sour” describes flavor.
- Sour mash is incorrectly treated as an American whiskey style.
Boundary examples
- Included: How backset helps condition mash pH from one distillation cycle to the next.
- Excluded: A comparison of yeast strains with no discussion of backset.
Semantic relationship
Parent Topic: 
Operational entity:
The Tag supports conceptual retrieval; the Domain Process describes the operation.
Governance decision
Duplicate and alias review found no competing child term. “Sour mash fermentation” was removed from the parent Topic’s aliases so exact retrieval resolves to this narrower record. Two Sources, two Verified Excerpts, two Literature Notes, one Zettel, two Claims, and one Domain Process support approval.