Vinegar shrub

A shrub is technically a preservation technique rather than a fermentation: ripe fruit is macerated with sugar (which extracts juice via osmosis), then steeped with vinegar to acidify the resulting syrup to shelf-stable pH. The final product is a concentrated sweet-tart syrup mixed 1:6 to 1:10 with water or soda water and drunk as a non-alcoholic cocktail substitute. Shrubs predate refrigeration and were a way to preserve seasonal fruit in usable form for many months.

The editorial reason to include shrubs in a fermentation encyclopedia: they sit at the intersection of fermentation (the vinegar itself is fermented) and preservation, and they showcase the role of acetic acid both as a finished product and as a preservation medium. A shrub made with apple cider vinegar (itself a wild ferment in traditional form) preserves strawberries or stone fruit into autumn, raspberries into winter.

The technique reemerged in modern American craft cocktail culture in the 2010s, where shrubs are now bottled commercially and used as cocktail components or non-alcoholic alternatives. The home version is simpler, fresher, and meaningfully different — a shrub made yesterday from peak summer berries does not taste like a shelf-stable commercial equivalent.