Tofu (Firm)

Tofu (Firm): Nutrition, History and Complete Cooking Guide

Tofu is a food made by coagulating soy milk with a coagulant — typically calcium sulphate (nigari in Japanese), magnesium chloride, or glucono delta-lactone — and pressing the resulting curds into solid white blocks. The process is structurally analogous to cheesemaking. Tofu was developed in China over two thousand years ago, with the earliest written records dating to the Han dynasty, and spread throughout East Asia as Buddhism promoted vegetarianism and the need for plant-based protein sources. In Japan, tofu became central to the Buddhist vegetarian cuisine of Zen monasteries and spread to become a fundamental everyday ingredient. It exists in multiple textures: silken tofu (very high moisture, smooth, custard-like, suited to blending and gentle preparations); soft tofu; firm tofu (the most common in British supermarkets — dense enough to cube, slice, and fry while holding its shape); and extra-firm tofu (pressed to remove maximum moisture, best for grilling and frying). The calcium sulphate coagulant used in firm tofu production significantly increases the calcium content of the finished product, making calcium-set tofu an excellent dietary calcium source.

Nutritional Value of Firm Tofu

Firm tofu (prepared with calcium sulphate) provides 144 kcal and 17.3 g of protein per 100 g, with 8.7 g of fat and 2.3 g of fibre. The protein is complete — tofu contains all nine essential amino acids in proportions that make it one of the few plant foods with protein quality comparable to animal foods. Calcium from the calcium sulphate coagulant is approximately 350 mg per 100 g — comparable to dairy milk and making tofu an outstanding calcium source for vegans. It provides iron, manganese, phosphorus, selenium, and copper. The fat is predominantly unsaturated, including the omega-3 alpha-linolenic acid and the omega-6 linoleic acid.

Health Benefits of Tofu

Tofu's complete, high-quality plant protein and exceptional calcium content make it nutritionally outstanding, particularly for those not consuming animal products. The isoflavones in soy — including genistein and daidzein — have been extensively studied. Once thought to have oestrogenic effects that raised concerns, the current evidence is broadly reassuring for moderate consumption: soy isoflavones appear to have a protective rather than harmful effect in the context of hormone-sensitive cancers when consumed in food form rather than high-dose supplements, and traditional soy-consuming populations (Japan, Korea) have lower rates of hormonal cancers than Western populations. Iron from tofu is non-haem and enhanced in absorption by eating alongside vitamin C-rich foods. Regular tofu consumption is associated with reduced cardiovascular risk in epidemiological studies, likely through a combination of protein quality, isoflavone activity, and replacement of less healthy protein sources.

How to Cook Tofu

For firm tofu, pressing is the key preparation step: wrap in a clean tea towel, place on a plate, weight with a heavy book for twenty to thirty minutes, and remove the expressed liquid — this dramatically improves texture and flavour absorption. Cut into cubes or slabs. For crispy pan-fried tofu: toss pressed, cubed tofu in cornflour, fry in hot oil for three to four minutes per side until golden and crispy. Season with soy sauce, sesame oil, and ginger. For marinated grilled tofu: marinate in soy, mirin, garlic, and ginger for thirty minutes, then grill or bake at 200°C for twenty minutes. Tofu absorbs flavours readily and is bland without seasoning — be generous with aromatics.