Kvass is a delightful traditional Slavic fermented drink. Originally it was made with bread and yeast, but fruit varieties are now most popular because they are especially appealing for children. In my book, Fuck Portion Control I talk about how most probiotic products are not helpful and sometimes even harmful because they are usually made of strains which are chosen for their hardiness through the distribution and packaging process and not because they are especially healthful. Contrary to popular belief, commercial yogurt can actually be quite harmful, because the sheer amount of lactic acid combined with aggressive lactic acid producers like Lactobacillus delbrueckii can effectively suppress populations of other bacteria which produce our important short chain fatty acids and permanently shift the microbiological composition of the gut, and large amounts of lactic acid can and do lower the metabolic rate. Kvass is a gentler probiotic that can be compared more to living bread. Plus, it’s downright delicious. This photo is of Berry Kvass, but my favorite is Nectarine. Any fruit can be used, as the point of using this is merely to deliver active culture and B vitamins. In the summertime you may want to brew a giant cooler of this, it’s so good and will go very fast, but make sure to never seal the container and to use it up within a few days or the ferment will become strongly sour. Don’t store longer than a week. DO NOT MIX IN A SEALED CONTAINER. IT WILL EXPLODE DUE TO LARGE AMOUNTS OF CO2 PRODUCTION AND WILL INJURE YOU OR OTHERS. Chlorine evaporates from water when boiled, so if non-chlorinated water is difficult to come by boiling the water works just fine (and all chlorine needn’t be removed, but high amounts can sometimes inhibit fermentation). Do not store for long—if you keep it more than several days it will start to produce alcohol.

FRUIT KVASS

1 pint water (preferably non-chlorinated)
1 cup organic sugar (less refined adds more complex flavor)
1-2 cups soft fruit of your choosing (blueberries, peaches, strawberries, nectarines, grapes, etc.)
1 tsp yeast (you can use a starter or dry active yeast)

Add the water and sugar to a large jar or other container and stir until dissolved. Cut or smash fruit and add to water, then add the yeast and Swiss cheese. Cover but do not tightly seal. Allow to ferment in a warm spot for at least 12 hours or overnight, but refrigerate before serving. You should see robust carbonation rising in the drink, when that occurs it indicates it’s ready to drink whenever you like. If you ferment it for very long the bacteria will consume all the sugar and produce large amounts of sour acids, so it’s best to consume before that point, and more sugar can be added if it no longer tastes very sweet. Serve with or without fruit as you desire. Do not store indefinitely. After several days it will begin producing alcohol. But leftovers can be used to start new, fresh batch of culture.