Retain acidic-backset conditioning only. Backset/stillage is not live yeast propagation; prior fermented wash and post-distillation backset are not interchangeable. Reject the nearby claim that sour mash ensures reuse of the same yeast strain and that sweet mash necessarily requires new yeast. Verified means faithful source location, not all underlying claims validated.
The passage follows the guide's bourbon mash-bill overview and precedes a contrasting explanation of sweet mashing.
The guide describes sour mashing as an optional production step rather than a sour flavor. It says acidic backset or prior fermented wash may be added to a new mash to supply nutrients, counter alkaline water, reduce contamination risk, and support batch consistency.
Printed p. 148 / PDF sheet 148
Printed p. 147 / PDF sheet 147
Chapter 5 — Bourbon Whiskey: Sour Mashing
Visually verified across rendered PDF sheets 147–148, displaying printed pp. 147–148. The paraphrase excludes the guide's imprecise opening reference to leftover yeast.
Verified, qualification-bounded paraphrase from the Society of Wine Educators' 2025 study guide.
Evidence
The guide describes sour mashing as optional and unrelated to a sour finished flavor. Its explicit backset discussion says acidic material may be returned to a new mash to supply nutrients, counter alkaline water, reduce contamination risk, and support consistency.
Location and context
Chapter 5, Bourbon Whiskey: Sour Mashing; printed pp. 147–148 / PDF sheets 147–148. The discussion precedes a contrast with sweet mashing.
Annotation
This supplies cautious tertiary corroboration for fermentation feedback control. The guide's looser introductory wording about leftover yeast is excluded from the retained definition.