Tofu

Tofu, also called bean curd, is a food prepared by coagulating soy milk and pressing the resulting curds into solid blocks. It is a traditional staple across China, Japan, Korea and Southeast Asia, and has become one of the best-known protein sources in vegan and vegetarian cooking worldwide. Tofu has a mild flavour, which allows it to absorb marinades and sauces and to be used in both savoury and sweet dishes.

History

Tofu originated in China. Chinese tradition attributes its invention to Liu An, a prince of the Han dynasty in the 2nd century BCE, but historians regard this as legend, and the earliest reliable written references date from considerably later, around the 10th century CE. From China, tofu spread to Korea and Japan, where its adoption is commonly associated with Buddhist monks and the vegetarian temple cuisine they practised. Tofu became widely known in Western countries during the 20th century, helped by interest in Asian cuisines, vegetarianism and later the growth of plant-based eating.

Production

The basic process is similar to cheese making, although no animal products are involved:

1. Dried soybeans are soaked in water, then ground with fresh water into a slurry.
2. The slurry is heated and strained to separate the liquid soy milk from the solid pulp, known as okara.
3. A coagulant is stirred into the hot soy milk, causing proteins and fats to form curds.
4. The curds are ladled into cloth-lined moulds and pressed to remove whey. Longer and firmer pressing produces firmer tofu.

Coagulants

The choice of coagulant affects texture, flavour and nutritional content:

• Nigari – a traditional Japanese coagulant derived from seawater, consisting mainly of magnesium chloride. It produces a smooth tofu with a slightly sweet taste.
• Gypsum (calcium sulfate) – long used in Chinese tofu making. It gives a tender texture and substantially raises the calcium content of the finished product.
• Glucono delta-lactone (GDL) – an acid often used for silken tofu, giving a very smooth, custard-like texture.
• Acids such as lemon juice or vinegar can be used in home production, though they give a less consistent result.

Types

Other traditional products include fried tofu puffs, tofu skin (yuba), which forms on the surface of heated soy milk, and fermented tofu, a pungent condiment.

Cooking techniques

Firm and extra-firm tofu are often pressed before cooking to remove excess water, which improves browning and helps marinades penetrate. Common techniques include:

• Pan-frying and deep-frying to create a crisp exterior.
• Baking or air-frying cubes coated lightly in starch and oil.
• Marinating in soy sauce, garlic, ginger or other flavourings.
• Crumbling firm tofu into a scramble as an alternative to scrambled eggs (see egg substitutes).
• Blending silken tofu into sauces, puddings, cheesecakes and mousses.
• Freezing and thawing, which gives a chewier, more porous texture that absorbs sauces well.

Nutrition

Tofu is a source of complete protein, meaning it supplies all essential amino acids. Nutrient content varies considerably by type and brand: firmer tofu contains less water and therefore more protein per serving. As an approximate guide, firm tofu typically provides around 10–15 g of protein per 100 g, while silken tofu provides roughly half that amount.

Tofu made with calcium sulfate can be a significant dietary source of calcium, and tofu also contributes iron and magnesium. It is low in saturated fat and naturally cholesterol-free. Readers should check product labels, since the coagulant and any fortification determine the exact values.

Health and safety notes

Soy is a common allergen, and people with soy allergy should avoid tofu. Concerns have sometimes been raised about soy isoflavones, plant compounds with weak oestrogen-like activity; major health bodies generally consider moderate consumption of traditional soy foods safe for most people. For broader context see vegan diet and health.

See also

• tempeh
• seitan
• plant based milks
• protein
• meal planning