Science and flavor
pH
JA: pH(ピーエイチ)
A scale from 0 to 14 measuring how acidic or alkaline a substance is.
What it means in a kitchen
Lower pH means more acidic. Lemon juice sits around 2.5, vinegar around 2.5–3, fermented pickle brine often around 3.5–4. Many food-safety guidelines treat home fermentation contexts below roughly pH 4.6 as sufficiently acidic; above that, the same guidelines treat the brine as still developing. Specific thresholds vary by ingredient and method — when in doubt, follow a trusted reference.