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Zoolak
Boil three pints of milk. Do not let scorch. When it is lukewarm add one eighth of a cup of old zoolak. Stir briskly, and let it stand for four or five hours until it is thick.
Koumiss No. 1 Mix one pint of buttermilk, two quarts of sweet milk, and six lumps of sugar. Pour from one pitcher to another for fifteen or twenty minutes, or until the sugar is dissolved. Cover with cheesecloth, and let it stand in a warm place for twelve hours. Then pour it into pint bottles, and seal securely. Fill only to within one inch and a half of the top. The koumiss will be ready for use in four or five days. Keep bottles lying on their sides in a cool place. Koumiss No. 2 Dissolve one fourth yeast cake in lukewarm water. Heat one quart of milk until lukewarm and add one tablespoonful of sugar and the yeast. Pour into bottles and seal at once securely. Stand in a warm place for twelve hours, then put on ice for twelve hours. It is then ready to serve. The milk should not be heated above 98 Deg. F. or 100 Deg. F. Do not fill the bottles full.
Three fermented-milk drinks printed as one entry. Two of the three are sealed-bottle fermentations built on milk that never gets hot enough to be safe, and neither gives an acidity target, a temperature range you could hold, or any way to judge when the culture has won. Read these as documents of pre-refrigeration invalid cookery rather than as working instructions.
- The milk is never made safeKoumiss No. 1 combines buttermilk with plain "sweet milk" and leaves it in a warm place for twelve hours before bottling; Koumiss No. 2 explicitly caps the milk at 98-100F, which is body temperature and an ideal incubator for Salmonella, Listeria and pathogenic E. coli. Milk of this period was in many places still sold raw. Nothing in either method reduces a pathogen load, and a slow, uncontrolled ferment gives contaminants a twelve-hour head start on the culture.
- Sealed bottles plus live yeastKoumiss No. 2 pitches a quarter of a baker's yeast cake into sugared milk and tells you to "seal at once securely" in glass. That is a carbonation charge with no vent and no gauge. The recipes' instructions to leave an inch and a half of headroom, and (in No. 1) to lay the bottles on their sides, are not pressure controls. Modern kefir and koumiss recipes ferment loosely covered, and bottle only with controlled headspace and regular venting.
- An undefined starterThe zoolak method depends on "one eighth of a cup of old zoolak" -- a backslop from a previous batch of a commercial product that no longer exists. Without a defined, viable culture the boiled milk simply sits and picks up whatever is in the room.
- "Old zoolak" and the backslopping problemCarrying a culture forward from batch to batch was a common enough household method, but it drifts. Each generation shifts the balance of organisms, and there is no instruction here for judging when a mother culture has gone off beyond "until it is thick." Thick is not the same as safely acidified.
- What the numbers meanThree pints is six cups; two quarts of sweet milk is eight cups. "Six lumps of sugar" is roughly two tablespoons, since a lump of the period ran a little under a teaspoon -- though lump sizes varied by supplier, so the figure is genuinely approximate.
- Yeast cakeA yeast cake of the era, whether compressed fresh or dried, was a different article from a modern packet of instant dry yeast, and the recipe does not say which is meant. A quarter cake is not equivalent to a quarter teaspoon of anything sold today, which is one more reason the quantities here will not translate.
- If you want the drinkCultured milk drinks are perfectly makeable now. Use a current kefir or koumiss recipe with pasteurised milk, a purchased live culture, and a stated fermentation temperature and time.
Zoolak was a branded fermented-milk preparation sold in the United States around the turn of the twentieth century, one of several products riding the wave of enthusiasm for soured milk as a health food. Koumiss proper is a Central Asian drink of fermented mare's milk, traditionally associated with the steppe peoples, and it reached Western medicine in the nineteenth century as the "koumiss cure" prescribed for consumption, dyspepsia and general wasting. Cow's-milk imitations like the ones here were the practical household substitute, since mare's milk was not to be had in an American kitchen. It is worth noting that genuine koumiss ferments to a low but real alcohol content, and the yeast in the second formula would have produced some too.