KVASS Wild or YEAST/Lactic fermented RYE BREAD water

General Information

In modern times, some soft drink makers produce a flavored non-alcoholic beverage they call Kvass. But that is not what were talking here! Traditional Kvass is definitely fermented. Kvass is a traditional Slavic (Russian) drink made from a yeast and lactic acid fermentation of Rye Bread in water. Its roots go back to the times before the middle ages. Kvass can be rye bread alone or sometimes rye bread mixed with nuts, raisins, berries, or sugar.

HACCP Category: Food Code 3-502.11 Special Process - Kvass is a wild culture or yeast/lactic acid bacterial culture fermented rye bread product.

Alcohol? If yeast is present, it will contain alcohol and possibly ≥ 0.5 ABV.


  1. 1 lb loaf of rye bread is cubed and optionally toasted. Add 1 gallon water. Add 1.5 c sugar, brown sugar or equivalent in honey. Add optional fruits (apples, raisins, berries) in small pieces.
  2. Boil the mixture briefly, then cool at ambient temperature.
  3. Inoculate with a brewer's culture for sour beer (yeast and lactic acid). An example would be a culture to make Berliner Weisse.
  4. Cover the fermentation vessel with a lid fitted with an airlock. The culture will produce gas, so some method to permit the gas escape is needed.
  5. Check and recheck the fermented beverage for pH. A pH ≤ 4.6 inhibits Clostridium botulinum and a pH ≤ 4.2 inhibits all foodborne illness bacteria. Allow the fermentation to proceed until gas formation ceases.
  6. Strain the Kvass from the solids and bottle. To get carbonated Kvass add 1/4 tsp sugar to each 12 oz bottle. Cap and allow to carbonate at ambient temperature. !! Bottling with too much residual sugar will result in higher levels of CO2 gas and a risk of container explosion !!


Kvass was historically a wild yeast and bacterial fermentation. The yeast converts the sugars into alcohol and CO2. It was likely that wild lactic acid bacteria were present and some Kvass would have had lactic acid sourness. Today, it is best to use a brewer's yeast culture to ferment the Kvass leading to the desired flavor profile. Wild or natural cultures may contain pathogens.


Rye bread water is considered a Temperature Control for Safety Food (TCS food). The Rye bread water is neutral in pH, has nutrients, and does not have antimicrobials. This means that in general, all of the possible foodborne illness bacteria can grow in this food/beverage.

  • Vegetative bacteria (e.g. E. coli O157, Listeria moncytogenes, Salmonella, and similar). Vibrio and Campylobacter are not expected in these types of foods.
  • Vegetative bacteria that produce toxins (Staphylococcus aureus)
  • Sporeforming bacteria that produce toxins (Clostridium botulinum, C. perfringens, and Bacillus cereus). B. cereus is associated with outbreaks in starches and grains.


CCP1: Boil all of the ingredients except for the fermentation culture. This will destroy all of the vegetative pathogens that might be present. Note that sporeformers will survive.

CCP2: Ferment RAPIDLY with an active culture to pH ≤ 4.6 and optionally ≤ 4.2. At pH ≤ 4.6 C. botulinum cannot grow and at pH ≤ 4.2 no foodborne illness bacteria can grow.

Photo credits (1) By S. Vecrumba - uploaded by P. Vecrumba, spouse of original photographer, CC BY 3.0. (2) By Edmund Schluessel - Sanyo S750i, Public Domain, (3-4) Fight bac - Public domain.

Created By
Brian Nummer