Tofu

Tofu, also known as soybean curd, is a soft, cheese-like food made by curdling fresh hot soymilk with a coagulant. Traditionally, the curdling agent used to make tofu is nigari, a compound found in natural ocean water, or calcium sulfate, a naturally occurring mineral. Curds also can be produced by acidic foods like lemon juice or vinegar. The curds then are generally pressed into a solid block.

Tofu was first used in China around 200 B.C. Although the discovery of the process for making tofu is lost to the ages, Chinese legend has it that the first batch of tofu was created by accident. A Chinese cook added nigari to flavor a batch of pureéd, cooked soybeans; the nigari produced the curd that we know today as tofu.

Today, tofu is a dietary staple throughout Asia. This delicate food is made fresh daily in thousands of tofu shops and sold on the street.

In recipes, tofu acts like a sponge and has the miraculous ability to soak up any flavor that is added to it. Crumble it into a pot of spicy chili sauce and it tastes like chili. Blend it with cocoa and sweetener and it becomes a double for chocolate cream pie filling. Cubes of firm tofu can be added to any casserole or soup.

Varieties

There are two types of tofu: traditional (Chinese-style) tofu and Japanese-style "silken" tofu. Traditional tofu comes in the following degrees of firmness (a function of how much water is left in the tofu): soft, firm, and extra-firm. There is also "lite" tofu, which is lower in calories and fat. Check the label carefully to make sure that you are purchasing the specific variety of tofu that will suit your culinary needs. For example, extra-firm tofu is best used for marinating and cutting into cubes for a stir-fry. The softer the tofu, the easier it is used for desserts or other foods that require a wetter consistency.

Silken tofu, called kinugoshi in Japanese, is made from soymilk that is strained before a coagulant is added. The tofu is then made in a process similar to yogurt, where the protein is not hardened into curds and no whey is drained off. This process makes the texture generally smoother, creamier, and more custardlike. Like traditional tofu, silken tofu comes in a range of firmnesses: soft, firm, and extra-firm. But even the extra-firm variety of silken tofu has a smoother consistency than other tofus, similar to flan. Silken tofu is best used for making dips, sauces, desserts, puddings, smoothies and "milk" shakes; any recipe that requires blending. Silken tofu may be substituted for sour cream, cream cheese, salad dressing, mayonnaise, or yogurt.

Tofu is rich in high-quality protein. It is also a good source of B-vitamins and iron. When the curdling agent used to make tofu is calcium salt, the tofu is an excellent source of calcium. While 50 percent of the calories in tofu come from fat, a 4-ounce serving of tofu contains just 6 grams of fat. It is low in saturated fat and contains no cholesterol. Generally, the softer the tofu, the lower the fat content. Tofu is also very low in sodium, making it a perfect food for people on sodium-restricted diets.

Source: Composition of Foods: Legumes and Legume Products. United States Department of Agriculture, Human Nutrition Information Service, Agriculture Handbook 8-16. Revised December 1986, and from product analysis.

Tofu most commonly is sold in water-filled tubs, vacuum packs, or in aseptic brick packages. Tofu is usually found in the produce section of the grocery store, although some stores sell tofu in the dairy or deli sections. Tofu is sometimes sold in bulk in food cooperatives or Asian markets. Unless it is aseptically packaged, tofu should be kept cold. As with any perishable food, check the expiration date on the package.

Once the tofu package is open, leftover tofu should be rinsed and covered with fresh water for storage. Change the water daily to keep it fresh, and use the tofu within a week.

Tofu can be frozen up to 5 months. Defrosted tofu has a pleasant caramel color and a chewy, spongy texture that soaks up marinade sauces and is great for the grill.

Tofu is for everyone. The soft consistency of tofu and its mild taste make it a perfect food for anyone. It is a good source of protein for elderly people who prefer dishes that are easy to chew and digest. Soft tofu that has been pureed with fruits or vegetables is a good first protein food for infants. Toddlers can enjoy chunks of cooked tofu for snacks or meals.

Try some of these ideas for introducing tofu to your family.

• Add chunks of firm tofu to soups and stews.
• Mix crumbled tofu into a meatloaf for a pleasant light dish.
• Mash tofu with cottage cheese and seasoning to make a sandwich spread.
• Create your own tofu burgers with mashed tofu, bread crumbs, chopped onion and your favorite seasonings.
• Marinate tofu in barbecue sauce, char it on the grill and serve on crusty Italian bread.
• Add a package of taco seasoning to pan-fried, crumbled tofu, or a mixture of tofu and ground beef to tofu tacos.
• Blend dried onion soup mix into soft or silken tofu for a cholesterol-free onion dip.
• Stir silken tofu into sour cream for a reduced-fat baked potato topper.
• Blend tofu with melted chocolate chips and a little sweetener to make a chocolate cream pie.
• Replace all or part of the cream in creamed soups with silken tofu.
• Make missing egg salad with tofu chunks, diced celery, mayonnaise and a dab of prepared mustard.
• Substitute pureed silken tofu for part of the mayonnaise, sour cream, cream cheese or ricotta cheese in a recipe. Use it in dips and creamy salad dressings.

Clinical studies and observational studies have often found a significantly reduced risk of breast cancer in Asians with increased soy consumption.
Soybeans contain a number of natural substances with demonstrated tumor suppression action or other anticarcinogenic activity in animal studies. Epidemiological evidence from Japan points to lower colon cancer incidence in areas with high tofu consumption.
In Japan the risks of breast, prostate and colon cancer are low and the Japanese have the highest levels of isoflavones in the blood. By contrast, Englishmen have the lowest levels of isoflavones in prostatic fluid and the highest rates of prostate cancer.
Japanese men, who eat a low-fat diet rich in soy proteins and have a low mortality rate from prostate cancer, have isoflavone levels seven to 110 times higher than Finnish men. Finnish men, typical of men in the West, have a much higher rate of prostate cancer and a diet high in fat and animal protein.

Soy protein may confer protection against osteoporosis and fracture risk by promoting a more optimal calcium balance. Substitution of soy protein for animal protein mitigates the adverse effects of high intakes of animal protein on calcium balance.

Soy protein with naturally occurring isoflavones can prevent bone loss secondary to ovarian hormone deficiency in animals.

Soy protein with isoflavones has been shown to increase both bone mineral content and bone mineral density in the lumbar spine.
Calcium in soy foods is highly available and is only slightly less-easily absorbed by the body than the calcium contained in cheese and milk.