Tofu is a soft-textured, pale-colored food with high protein content, produced by coagulating a milk-like liquid extracted from soybeans using various coagulants. Originating in China, tofu has been widely used throughout East Asian cuisines such as those of Japan, Korea, and Vietnam. Since the 20th century, it has become a globally consumed product in the Western world due to the influence of vegetarian, vegan, and alternative dietary models. Tofu has been the subject of numerous academic studies not only in food technology but also in cultural, biochemical, nutritional science, and public health contexts.

Basic Characteristics

Tofu is primarily made by coagulating proteins in soy milk. Common coagulants include calcium sulfate (CaSO4), magnesium chloride (MgCl2), and glucono delta-lactone. These coagulants cause the proteins to curdle, and the resulting curds are pressed in cloth bags to form tofu blocks of varying firmness. The product is rich in highly bioavailable protein. Because its flavor is neutral, tofu easily absorbs different spices, sauces, and cooking methods.

The texture and flavor profile of tofu vary depending on factors such as the type and amount of coagulant used, pressing time, and temperature. Accordingly, tofu is commonly classified as silken (soft), medium firmness, and firm tofu.

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History and Cultural Diffusion

Origin in China

Tofu traces its origins to China, with historical records dating back to the Han Dynasty (2nd century BCE). According to some sources, the first production of tofu is attributed to Liu An, a prince of that era. Tofu gained significant importance in Buddhist cuisine as a high-protein alternative to meat.

Spread Across East Asia

From China, tofu spread to Japan, and subsequently to Korea and Southeast Asian countries, where it was adapted with regional variations in production and consumption. In Japan, the term “tofu” is directly used, with slight regional differences in production techniques. In Korea, tofu is called “dubu” and is commonly used in soups, fried dishes, or as a side dish. In countries such as Vietnam and Taiwan, fermented versions of tofu are widely consumed.

Adoption in the Western World

Tofu began gaining recognition in Western countries during the second half of the 20th century, largely due to the rise of alternative and plant-based diets. Particularly from the 1970s onward, the increasing popularity of vegetarianism and veganism contributed to the expansion of tofu production, distribution, and consumption. Its low cholesterol content and lack of animal products made it a preferred food in diets aimed at reducing chronic disease risk.

Production Process

Soy Milk Production

The tofu production process starts with soaking, grinding, and filtering dry soybeans. The beans are soaked for 8–12 hours, then ground and mixed with water, followed by cooking. The mixture is strained to obtain “soy milk.” This stage separates water-soluble proteins and carbohydrates.

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Coagulation and Pressing

Coagulants are added to heated soy milk to induce protein coagulation. The coagulated proteins thicken into a curd, which is then placed in cloth bags and pressed under specific pressure. The pressing time and pressure level are the main factors determining the firmness of the resulting tofu.

Cooling and Packaging

The pressed tofu is cooled in cold water to stabilize its texture. It is then packaged under hygienic conditions for consumption. Industrial production often employs vacuum packaging and pasteurization to extend shelf life.

Types of Tofu

Classification by Texture

• Silken Tofu (Soft): High water content with a jelly-like texture, commonly used in desserts or sauces.
• Medium Firmness Tofu: Suitable for both frying and boiling.
• Firm Tofu: Low water content and pressed texture; preferred for frying, grilling, and baking.

Processed Tofu Varieties

• Fermented Tofu: Made by aging tofu cubes with salt and yeast, resulting in a strong aroma.
• Dried Tofu: The firmest tofu variety due to extensive pressing; it has a hard texture and a long shelf life.
• Frozen Tofu: Freezing causes crystal formation in the cell structure, producing a spongy texture with increased liquid absorption.

Nutritional Content and Composition

On average, 100 grams of tofu contains about 8–12 grams of protein. Fat content varies by type, but it is generally low, and tofu contains no cholesterol. It is low in fiber but rich in minerals like calcium and iron. Fermented tofu varieties also contain probiotic microorganisms.

The amino acid profile of tofu is comparable to that of animal protein sources. Therefore, tofu plays an important role in supplementing essential amino acids often limited in plant-based diets.

Microbiological and Biochemical Properties

Thermal processing and coagulation during tofu production significantly reduce microbial contamination risks. However, improper storage may allow microbial growth. Fermented tofu develops through controlled microbial activity.

Biochemically, tofu contains compounds such as isoflavones, lectins, saponins, and phytates. Some of these increase bioavailability, while others act as antinutrients (inhibiting nutrient absorption). Modern production techniques aim to balance these components and enhance the functional properties of the product.

Tofu and the Food Industry

Tofu has wide applications not only in home cooking but also in industrial food production. Ready meals, frozen products, desserts, and beverages often incorporate tofu. It is valued as a functional food and a meat analogue a meat substitute).

Tofu is also emphasized as a sustainable food source. Compared to animal agriculture, soybeans have a lower carbon footprint and require less water consumption.

Cultural and Social Contexts

Tofu is not only a food item but also a cultural identity element. In Chinese, Japanese, and Korean cuisines, special holiday dishes, rituals, and belief practices involve tofu. In the modern era, globalization, migration, and intercultural exchange have integrated tofu into international cuisines.