Okara (soy pulp, tofu dregs) is a by-product of soy milk production. It has a neutral taste and works well as a binder for soups and sauces.
From Wikipedia: “Okara, soy pulp, or tofu dregs is a pulp consisting of insoluble parts of the soybean which remains after pureed soybeans are filtered in the production of soy milk and tofu. It is generally white or yellowish in color. It is part of the traditional cuisines of Japan, Korea, and China, and since the 20th century has also been used in the vegetarian cuisines of Western nations.
It is called dòuzhā or dòufuzhā in Chinese, okara in Japanese, and biji or kongbiji in Korean.
Okara is the oldest of three basic types of soy fiber. The other two are soy bran (finely ground soybean hulls), and soy cotyledon/isolate fiber (the fiber that remains after making isolated soy protein, also called "soy protein isolate").”
Making okara yourself in just five steps:
Soy milk is made by soaking dried soy beans in water and then pureeing them. You can purchase organic soy beans in supermarkets, Asian stores, and organic health stores. Use the following five steps to make your own okara; you can also make your own (raw) soy milk using these steps.
1) Soak one cup of dried soybeans (approx. 180 g) overnight in a bowl of water. Since the volume of the soybeans will increase greatly, you should cover the beans with a generous amount of water.
2) After soaking, pour the beans into a sieve and rinse well with running water. For the following steps, you will need a water to soybean ratio of 3:1.
3) Puree one cup soybeans with one cup water until you achieve a creamy consistency (depending on your blender, this will take 1½–3 minutes). Then gradually add the rest of the water to the blender. (If you add less water, the soy milk will be more concentrated.)
4) Line a sieve with a linen cloth or cheesecloth and place over a bowl or other container. Pour the pureed mixture through the sieve. Alternatively, you can pull the cloth tightly over the bowl and not use the sieve. After the liquid runs into the bowl, you should form a sack with the cloth and then squeeze any remaining liquid from the pulp.
5) This method allows you to separate the soy milk from the pulp. The pulp in the cloth is the okara. You can freeze or dry the okara so that it keeps longer.
You can find additional information about how soy milk is made under the following ingredient: vanilla soy milk.
“Okara that is firmly packed consists of 3.5 to 4.0% protein, 76 to 80% moisture and 20 to 24% of solids. When moisture free, the gritty okara contains 8 to 15% fats, 12 to 14.5% crude fiber and 24% protein, and contains 17% of the protein from the source soybeans. It also contains potassium, calcium, niacin. Most of the soybean isoflavones are left in okara, as well as vitamin B and the fat-soluble nutritional factors, which include soy lecithin, linoleic acid, linolenic acid, phytosterols, tocopherol, and vitamin D. Okara contains some antinutritional factors: trypsin inhibitors (mostly destroyed by cooking), saponins, and hemagglutinin, which cannot be easily digested. Fermentation (by proper species of bacteria) of okara is not only conducive to digestion and absorption of okara nutrients, but also further improves the nutritional value. It can eliminate the bean’s odor, increase the amount of edible fiber, free amino acids, sugars, fatty acids, vitamin B12, vitamin B2, and flavoprotein.”
“Most okara worldwide is used as feed for livestock - especially hogs and dairy cows. Most of the rest is used as a natural fertilizer or compost, which is fairly rich in nitrogen. A small amount is used in cookery.”
“While relatively flavourless when eaten on its own, it can be used in stews such as the Korean biji-jjigae or in porridges. It's also used as an addition to baked goods such as breads, cookies and muffins, and can serve to create a crumbly texture in these foods.
In Japan it is used in a side dish called unohana which consists of okara cooked with soy sauce, mirin, sliced carrots, burdock root and shiitake mushrooms.
Okara can be used to make tempeh, by fermenting with the fungus Rhizopus oligosporus, using a tempeh starter, or to make presscake tempehs that use ingredients such as brown rice, bulgur wheat, soybeans and other legume and grain combinations.
Okara is also eaten in the Shandong cuisine of eastern China by steaming a wet mixture of okara that has been formed into blocks of zha doufu also known as xiao doufu or cai doufu.
The product is sometimes used as an ingredient in vegetarian burger patties. Additional uses include processing into a granola product, as an ingredient in soysage and as an ingredient in pâtés.”
“Most okara is used as animal feed, especially for farms in vicinity of soy milk or tofu factories.”
In pet food:
“The product is also used as an ingredient in pet foods.”
As fertilizer or compost:
“Okara is sometimes spread on fields as a natural nitrogen fertilizer. It also adds tilth to the soil. Likewise, it can be added to compost to add organic nutrients and nitrogen.”
“When not considered foodstuff, it may be deemed soybean curd residue (SCR). Some 800,000 tons of soybean curd residue is disposed annually as tofu production byproducts, just in Japan. As mass waste, it is a potential environmental problem because it is highly susceptible to putrefaction. The protein in SCR is of better quality than from other soy products; for example, the protein efficiency ratio of SCR is 2.71 compared with 2.11 for soymilk, but the ratio of essential amino acids to total amino acids is similar to tofu and soymilk. Nevertheless, it remains a challenge to current processes to commercially extract the proteins and nutrients from SCR waste.”