For years people have been asking me to try fermenting sauerkraut with whey. I procrastinated for a long time, partially because I don’t keep dairy animals and so seldom have whey on hand, and partially because I saw no good reason to introduce an animal product to my vegetable crock (although I do like fishy kimchi).
But lately my daughter has been making a lot of cheese, and we’ve had a lot of whey to find uses for. So I consulted Klaus Kaufmann and Annelies Schöneck’s little book Making Sauerkraut and Pickled Vegetables at Home. The authors explain that “because it contains lactose and several vitamins and minerals, whey is an excellent aid to start the fermentation process.”
I was still in the dark. Whey comes from fermented milk; the lactose that was in the fresh milk has already been converted to lactic acid. The microbes that naturally ferment cabbage also produce lactic acid. In what way could adding lactic acid before fermentation help?
In spite of my doubts, I went ahead and made a small batch of sauerkraut with whey, using approximately one-fifth the quantities in Kaufmann and Schöneck’s recipe for–
Low-Salt Sauerkraut
2½ pounds slivered cabbage
1 teaspoon pickling salt
1/3 cup chopped onion
½ teaspoon caraway seeds
2 juniper berries
1 cup whey
Brine: 1 teaspoon pickling salt dissolved in 2 cups water
Toss together all the ingredients except the whey. The vegetables will take longer to wilt than they would with more salt, so wait about 15 minutes. Then pack the vegetables firmly into a 2-quart jar. Pour the whey over (the amount here is proportionally a bit more than Kaufmann and Schöneck call for; I needed this much to cover the vegetables).
Push a freezer-weigh quart plastic bag into the top of the jar, pour in the brine, and seal the bag.
If liquid doesn’t cover the sauerkraut by the next day, add a little of the brine from the bag.
Let the cabbage ferment for two weeks, say Kaufmann and Schöneck, or eat the cabbage as soon as it’s as tart as you like. It will keep for a long time in the refrigerator.
The fermentation proceeded normally, with no slime or mold or other nasty developments. I decided to serve the kraut early, after just a week, because I sometimes prefer it when it’s still crisp. I liked the seasonings; the caraway came through strong. I also liked that the kraut was less salty than usual. And if I hadn’t added the whey myself I wouldn’t have noticed it.
So, what was the purpose of adding whey? The same, I suspect, as adding salt and sometimes a little vinegar at the beginning of lactic-acid fermentation: These ingredients help keep bad microbes, like mold, from growing while fermentation gets under way, and they also slow the fermentation, thus allowing full flavors to develop. The whey took the place of additional salt.