Friday, January 16, 2009

Increasing Nutritional Value of Food: Lactic Fermentation

One of the simple techniques you can use to increase the nutritional value of your food is lactic fermentation. I've posted about this before, here and here. I thought what I would do here is provide a couple of brief introductions, one from Preserving Food Without Freezing or Canning (reviewed here), and another from Sally Fallon's Nourishing Traditions. Their descriptions of the process and the "how-to's" are simple and elegant. While there is naturally some repetition in the two descriptions, they have slightly different takes and provide a few different details that make it worth reading both.

I think you'll be convinced to try this age-old artisianal craft for preserving some of your harvest this coming year.

Preserving Food by Lactic Fermentation

Preserving vegetables for months, using neither heat, cold, nor preservatives, yet retaining the original freshness and nutritional value of these vegetables--this is the "miracle" of lactic fermentation.

The process is so easy and effective that we wonder why it has nearly disappeared from use. Still used for making sauerkraut, and for turnips in a few farms in Alsace and in Franche-Comte, lactic fermentation was the primary method for preserving vegetables before heat sterilization was discovered. Let's recall how it is done.

The vegetables are grated or cut up, seasoned with a bit of salt (or a mild brine) and herbs, and left to soak in their own juice. (Salt is a key: A good rule of thumb is about 1 1/2 percent salt by weight of vegetables, which generally translates into 2-3 tablespoons of salt per quart.)

Lactic microbial organisms--similar to those that curdle milk--develop spontaneously and convert the natural sugars of the vegetable into lactic acid. This environment rapidly acidifies, to the point that it becomes impossible for bacteria responsible for food spoilage to muliply. Vegetables preserved this way will keep in a cool place, such as a cellar, for many months.

This process is remarkable in its simplicity, effectiveness, and beneficial effects on nutritional value and digestibility. For most people who discover them, lacto-fermented vegetables become part of their daily diet and provide year-round access to ready-to-eat raw vegetables. Due to their acidity, however, they should not be eaten in large quantities; they should complement rather than replace cooked and raw vegetables. We prefer to eat lacto-fermented vegetables uncooked, to retain their enzyme and vitamin contrent, although certain ones, such as sauerkraut, can also be cooked. Once cooked, larger quantities of these foods can be eaten, since cooking reduces their acidity (however, cooking will also destroy some of the nutrients).

One other cautionary note: Don't use tap water in these recipes if it is chlorinated, because chlorine inhibits lactic fermentation. Also, the stones should be noncalcerous, that is, not comprised of limestone, calcium carbonate, or calcium.

For further information about lactic fermentation, see Beatrice Trum Hunter, Fermented Foods and Beverages (Keats Publishing, 1973).

*CAUTION: The USDA and the FDA recommend that all fermented foods should also be canned in a hot water bath to protect against botulism. However, traditional lacto-fermentation methods such as those described here seem to effectively prevent botulism by creating a sufficiently acidic environment. There is good reason to think these recipes are safe without canning. Readers should of course use their best judgment.

And from Nourishing Traditions:

Fermented Vegetables & Fruits

It may seem strange to us that, in earlier times, people knew how to preserve vegetables for long periods without the use of freezers or canning machines. This was done through the process of lacto-fermentation. Lactic acid is a natural preservative that inhibits putrefying bacteria. Starches and sugars in vegetables and fruits are converted into lactic acid by the many species of lactic-acid-producing bacteria. These lactobacilli are ubiquitous, present on the surface of all living things and especially numerous on leaves and roots of plants growing in or near the ground. Man needs only to learn the techniques for controlling and encouraging their proliferation to put them to his own use, just as how he learned to put certain yeast to use in converting the sugars in grape juice to alcohol in wine.

The ancient Greeks understood that important chemical changes took place during this type of fermentation. Their name for this change was "alchemy." Like the fermentation of dairy products, preservation of vegetables and fruits by the process of lacto-fermentation has numerous advantages beyond those of simple preservation. The proliferation of lactobacilli in fermented vegetables enhances their digestibility and increases vitamin levels. These beneficial organisms produce numerous helpful enzymes as well as antibiotic and anticarcinogenic substances. Their main by-product, lactic acid, not only keeps vegetables and fruits in a state of perfect preservation by also promotes the growth of health flora throughout the intestine. Other alchemical by-products include hydrogen peroxide and small amounts of benzoic acid.

A partial list of lacto-fermented vegetables from around the would is sufficient to prove the universality of this practice. In Europe the principle lacto-fermented food is sauerkraut. Described in Roman texts, it was prized for both its delicious taste as well as its medicinal properties. Cucumbers, beets and turnips are also traditional foods for lacto-fermentation. Less well known are ancient recipes for pickled herbs, sorrel leaves and grape leaves. In Russia and Poland one finds pickled green tomatoes, peppers and lettuces. Lacto-fermented foods form part of Asian cuisines as well. The peoples of Japan, China and Korea make pickled preparations of cabbage, turnip, eggplant, cucumber, onion, squash and carrot. Korean kimchi, for example, is a lacto-fermented condiment of cabbage with other vegetables and seasonings that is eaten on a daily basis and no Japanese meal is complete without a portion of pickled vegetables. American tradition includs many types of relishes--corn relish, cucumber relish, watermelon rind--all of which were no doubt originally lacto-fermented products. The pickling of fruit is less well known, but, nevertheless, found in many traditional cultures. The Japanese prize pickled umeboshi plums, and the peoples of India traditionally fermented fruit with spices to make chutneys.

Lacto-fermented condiments are easy to make. Fruits and vegetables are first washed and cup up, mixed with salt and herbs or spices and then pounded briefly to release juices. They are then pressed into an air tight container. Salt inhibits putrefying bacteria for several days until enough lactic acid is produced to preserve the vegetables for many months. The amount of salt can be reduced or even eliminated if whey is added to the pickling solution. Rich in lactic acid and lactic-acid-producing bacteria, whey acts as an inoculant, reducing the time needed for sufficient lactic acid to be produced to ensure preservation. During the first few days of fermentation, the vegetables are kept at room temperature; afterwards, they must be placed in a cool, dark place for long-term preservation.

It is important to use the best quality organic vegetables, sea salt and filtered or pure water for lacto-fermentation. Lactobacilli need plenty of nutrients to do their work; and, if the vegetables are deficient, the process of fermentation will not proceed. Likewise if your salt or water contains impurities, the quality of the final product will be jeopardized.

Finally, here's the recipe I use to make fermented red onions, which I eat nearly every day with whatever else I'm having for lunch. They're delicious and to me, irresistable. I crave them if they're not around...

Fermented Red Onions

2 red onions, chopped
1 tablespoon sea salt
4 tablespoons whey
filtered water to cover

Chop up the red onions, pack them tightly into a quart jar. Add sea salt and whey. Cover onions up to within one inch of the top of the jar with the water. Put the lid on the jar. Leave at room temperature for 4 days (depending on your room temp). You may find some white froth at the top of the jar, but just spoon that off. After the 4 days or so (smell them to see if the onions smell tangy), put them in the fridge and enjoy!



Abraham said...

Great post. This stuff is great. I love making Kim Chi. It's amazing how you can slice up five pounds of cabbage into this huge pile let it sit in salt overnight and you wake up to a little pile of cabbage and a big pile of salt water.

Patricia said...

Hey Abraham--yes, I love the fermenting process too. And the results! It is a terrific way to preserve foods that taste great and are even better for you than when you started. I hope lots of folks pick up on it.