The milk is mixed with either salt or a coagulating agent (frequently calcium, which adds to the nutrition). This process produces curds and whey, just as cheese making does. The protein separates into a soft curd and we have tofu. The whey is then pressed out of the curd, and the curds are pressed into boxes where they are pressed. The resulting slabs are then divided into the size sold in stores.
Pressing determines the type of tofu. The longer it is pressed, the firmer and less liquid it will be. Should you purchase a tofu that is not as firm as you'd like, you can press it yourself between plates and extract even more of the liquid.
It is possible to make tofu at home, however it is a long process and, frankly, not worth the effort when there are so many fine products on the market. One of the advantages of tofu is that it is convenient.
Types of Tofu or Bean Curd
Extra firm tofu: This form contains the least amount of water of any type of tofu. It holds its shape which makes it easy to cut. It withstands frying or broiling and is excellent used in casseroles and stir fry dishes. It is the highest in protein, fat and calcium (when coagulated with calcium.
Firm tofu: This is slightly less dense, but is also excellent used as the extra-firm. It holds its shape for slicing, dicing and frying. Firm tofu works well in desserts and dressings and as a cheese substitute, particularly for cottage cheese, ricotta or cream.
Soft Tofu: This is is very tender, perfect ideal for blending into dressings and sauces. It can be used to reduce the amount of egg used in a recipe and to replace sour cream or yogurt. Soft tofu also is lower in both protein and fat. Soft tofu crumbles easily.
Silken Tofu: Silken tofu has the finest consistency of any tofu, and silken is the appropriate word to describe its custard-like texture. This is wonderful for dips and dressings, even for smooth puddings. When pureed, it can be mixed with mayonnaise, sour cream, cream cheese or ricotta cheese in a recipe to lower the fat calories from these normally fatty products.
Lite Tofu: Needless to say, manufacturers accommodate. “Lite” tofu contains fewer calories and fat.
Organic Tofu: A tofu produced by FDA organic standards.
Baked or smoked tofu: Pre-flavored by the manufacturer, it is a convenience food par excellence, ready to can be tossed straight from the package into salads, stir-fry dishes, noodle dishes.
Chinese Fried Bean Curd (or Tofu): These can be found in Chinese stores. The Chinese is sold in cubes about one to one and a half inch thick. They may be frozen or will stay fresh in the refrigerator for about 4 to 5 days.
Japanese Fried bean Curd (or Tofu): There are two major types of fried bean curd in Japan. Age is a thick, rectangular piece of tofu, expressly fried to have a crispy exterior, but a soft inside. Aburage is thinner and is meant to be opened into pouches. There is less inside than in the Chinese variety, and it is a spongy texture. Both can be found in Japanese stores in the refrigerator section.
Fermented Bean Curd or Tofu: This is primarily Chinese and Thai and is generally bottled or canned and will last almost indefinitely if kept in a closed container in the refrigerator. These are small cubes, about 1/2 to 3/4 inch and are very salty.
Pressed Bean Curd or Tofu: As the name implies, most of the water has been pressed out of this form of bean curd. It is sold in cakes which are about 1/2 inch thick. Being hard and drier than most tofu products, this is excellent for dicing and slicing to add to salads or a s a garnish to dishes. It is stored in a salty water in the refrigerator and will last about two weeks.
Pressed Seasoned Bean Curd or Tofu: This is similar to the plain pressed, but is cooked in a soy and star anise solution and has an anise flavor. It has a brown color from the soy. It is used and stored as the plain pressed bean curd.
Dried Bean Curd or Tofu Skin: Soy milk, being similar in properties to cow's milk, will form a skin when heated. This is sold in sheets in both Chinese and Japanese stores. It always needs to be reconstituted by soaking in water. It does not need refrigeration, but it turns rancid when not used quickly.
Tofu Nutrition Facts
Wild claims have been made for tofu, enough that one would think that the fountain of youth had been discovered. We are wary of such claims, preferring to simply look at the nutrition elements in any foodstuff, and as always, we try to get our best nutrition from foods themselves. We hope you, too, will assume an attitude of cheerful skepticism. Soybeans are rich in nutrition which is fine with us. (But please do advise if you uncover the fountain of youth.)
Tofu is a high-quality protein, containing all nine amino acids. It is also a good source of B-vitamins and iron. There are many different curdling agents used to make tofu among them calcium. If made with calcium, it is also a nutritionally sound source of calcium. Check the package label.Tofu also contains isoflavones, which may help to prevent chronic diseases such as cancer and heart disease.
Half of the calories in tofu come from fat, however, tofu is low in saturated fat and cholesterol-free. Generally, the softer the tofu, the lower the fat content. Tofu is also very low in sodium. According to the FDA, clinical studies have shown that consumption of soy compared to other protein, such as those from milk or meat, lowers total and LDL cholesterol. he sub-nutrients of soy and tofu, finding that consuming soy isoflavones can reduce chances of cancer. Asian women don’t suffer the side effects of menopause like Western women do, including hot flashes and osteoporosis, thanks to estrogen- and calcium-packed soy. Isoflavones are naturally-occurring plant compounds that have been attributed in numerous medical and scientific studies to reducing risk of colon, breast and prostate cancer.
As a side note, another product of the soybean is its oil which is low in saturated fat and high in poly- and monounsaturated fats. It is also one of the few non fish sources of omega-3 polyunsaturated fatty acids, which may be beneficial in helping to prevent cancer and heart disease.
Soy supplements: We do not recommend supplements made from isolated soy components, particularly isoflavones. Many claims are made on labels, but the bottom line is that you generally don't know what you're getting. By "soy supplements" we mean capsules and pills—not soy powders or soy concentrates.
Those supplements that contain concentrated isoflavones should be avoided. No one knows what the long-term effects of concentrated isoflavones might be. Marketers never mention all the unknowns and the possible adverse effects. If you are eating tofu on a regular basis, you are adding to your nutrition in the most natural way.
For very detailed information on soy and disease, please refer to this site: http://www.talksoy.com/Home.htm
Buying & Storing Tofu
Tofu is a perishable product. It has an expiration date printed on its label. As always, we recommend you check the label. If it is packaged in water, you can keep it, unopened, in the refrigerator until ready to use.
Once the package is opened, tofu needs to be stored in water to cover and the water needs to be changed daily. If not, the tofu will dry out and absorb the flavors of other foodstuffs in the refrigerator.
Tofu also can be frozen for up to five months. Defrosted tofu is chewier than fresh and will freely absorb flavorings. Do not freeze tofu in its original package. Remove tofu from the package, drain off the water. Rinse the tofu under running water, then wrap in plastic wrap and freeze immediately. Freezing also revives leftover tofu. To thaw tofu you can microwave it on a paper towel or in a bowl, or boil it for 5 to 25 minutes, according to size. Or you can let it thaw, lightly covered, on a plate on the kitchen counter. This will take a couple of hours.
Pressing & Draining Tofu
We don't want water seeping into our cooked foods and tofu will drain of its own. To firm it, place the tofu between paper or cloth towels and put a heavy weight (a one-pound can, a heavy pan, or a brick) on top of the tofu. Allow to sit for an hour or so. It will drain, so be sure to put something to catch excess liquid, or change the toweling during the process.