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Soft drinks from Roman Empire, Byzantium

Poscaposca (Latin)

Posca was the Roman soldiers' and poor people's drink of sour wine or wine vinegar mixed with water. The only ferment is the vinegar, made when acetic acid bacteria sour wine; the drink itself is simply mixed.

Fully documentedSoft drinks6 months – 12 months

Recipe

Amounts from a sourceThe amounts are a modern reconstruction from the Kelsey Museum of Archaeology. No ancient source gives a recipe or a ratio of vinegar to water.
Red wine vinegar2 tbsp[kelsey-posca]
Chilled water1 cup[kelsey-posca]
Honey1 tbsp, optional[kelsey-posca]
Starternone at the mixing stage; the vinegar came from wine soured by acetic acid bacteria

Total time across the recorded steps: 6 months – 12 months

Start
Drag the bar or press Play
shapes, not to countYeastsSugarAlcoholCO₂

What changes: Yeast turns grape juice into wine, the base of the vinegar

Step 1 of 4
Ferment grape juice into wine
Time
Not documented
Temperature
Not documented
Salt
None given
Acidity
Not documented
Which microbes the steps name, step by step
Yeasts
Acetic acid bacteria

The Roman sources name acetum (vinegar) but not how it was made; this step is the wine that the acetic acid bacteria start from. Output: wine.

Flavour
Not documented
Texture
Not documented
Colour
Not documented

Microbes at work in this step

yeasts turn grape sugar into the alcohol that vinegar bacteria later use

Method

Measured measured in a studySet fixed by a specification or tested recipeReported one source reports itTypical a general value, not sourced for this fermentUnconfirmed not yet checked against a source

At a glance

Posca was the Roman soldiers' and poor people's drink of sour wine or wine vinegar mixed with water. The only ferment is the vinegar, made when acetic acid bacteria sour wine; the drink itself is simply mixed. Made in 4 steps over 6 months – 12 months. The longest step, wine sours into vinegar, takes 6–12 months (Mas A 2014). Acetobacter in traditional slow vinegar making, with Komagataeibacter (such as K. europaeus) taking over as acidity rises does most of the fermenting.

Key numbers
Main step6–12 monthsReported[mas2014]Wine sours into vinegar

What makes this one different

Posca is not fermented itself. It is wine vinegar, an acetic ferment, diluted with water. Oxymel, a mixture of honey and vinegar, was used as a medicine.

Campaign ration, AD 360
A law of Constantius II and Julian lists the campaign issue as wine one day and vinegar (acetum) the next, alongside biscuit, bread, bacon and mutton.
Camp fare
Hadrian is said to have eaten camp food in the open, bacon, cheese and posca, to set an example to his troops.
Wine banned on campaign
Pescennius Niger is said to have ordered his soldiers to drink no wine on campaign and to make do with vinegar.

Related ferments

Variants

  • Byzantine phouskaVinegar-water of the Byzantine army; a medical recipe by Aëtius adds herbs, spices and salt (Wikipedia, citing Dalby).
  • OxymelHoney plus vinegar, used as a medicine (Wikipedia).

Safety

Vinegar made the drink sour; the Kelsey Museum notes it masked impurities in water and killed some bacteria. That is a historical note about some bacteria only, so do not count on this dose of vinegar to make unsafe water safe.

History and sources

Every number is labelled with how it is known. How this atlas is made

Posca was a drink of Roman soldiers and the lower classes. The Historia Augusta has Hadrian eat camp fare of bacon, cheese and posca, and Pescennius Niger order his troops to drink vinegar instead of wine on campaign. The Theodosian Code (7.4.6, AD 360) issues soldiers on campaign wine one day and vinegar the next.

Temperature, salt and pH
The sources we found give no temperature, salt or pH figure for any of its steps.
  1. [ha-hadrian] Historia Augusta, Life of Hadrian 10.2 (Latin text and Loeb translation), LacusCurtiusarchive
  2. [ha-niger] Historia Augusta, Life of Pescennius Niger 10.3 (Loeb translation), LacusCurtiusarchive
  3. [cth-7-4-6] Codex Theodosianus 7.4.6 (AD 360, Constantius II and Julian to Helpidius), Latin text, Université Grenoble Alpesarchive
  4. [mas2014] Mas A., Torija M.J., García-Parrilla M.C., Troncoso A.M. 2014, Acetic acid bacteria and the production and quality of wine vinegar, ScientificWorldJournal 2014:394671, doi:10.1155/2014/394671paper
  5. [kelsey-posca] Kelsey Museum of Archaeology (University of Michigan), Posca recipe sheet (after the website Pass the Garum)other
  6. [s1] Wikipedia, Poscawiki