Associate Professor Dr. Nguyen Duy Thinh from the Institute of Biotechnology and Food Technology, Hanoi University of Science and Technology, stated that gypsum is used as a food additive within regulated quantities and quality requirements. Facilities using this additive in food production must comply with food safety regulations, ensuring the correct type, quality, and permissible levels. Gypsum must be a standard-compliant type with appropriate purity.

Tofu is a plant-based protein made from soybeans. The process involves soaking, crushing, cooking them into soy milk, and then using a coagulant to solidify it. Some tofu producers, aiming to cut costs, might use industrial gypsum unsuitable for food, posing potential risks to product quality and safety.

If unregulated coagulants are used to increase the amount of precipitate, tofu yield may rise, but product quality and safety become a concern. Consumers can observe certain external characteristics and feel the tofu when holding or preparing it to gain insight into whether it contains gypsum.

Quality tofu is typically soft, elastic, and relatively pliable. When held, a piece of tofu feels soft, not overly firm or dry. In contrast, products with unusual characteristics might be harder and firmer, with edges tending to be stiff and surfaces drying quickly. Consumers can cut across a piece of tofu to examine its interior. Naturally textured tofu usually has a relatively soft, smooth, uniform, and moist interior. If the tofu is overly firm, dry, fibrous, or feels unusual when cut, buyers should be cautious.

For fried tofu, further observations can be made after cooking. Tofu with a firm texture often maintains its shape well and is less likely to break apart when fried. However, tofu's firmness also depends on how it is pressed, its water content, soybean type, and preparation method. Therefore, one cannot solely rely on ease of frying or resistance to breaking to conclude that a product contains gypsum. After frying, good quality tofu typically has a crispy golden exterior while its interior remains soft, moist, and somewhat porous. If the interior becomes excessively dry, hard, fibrous, or has an unusual taste, consumers should discontinue use.

Some tofu containing gypsum might appear yellowish instead of the creamy white color of pure tofu. However, color alone may not be an accurate indicator, as even pure tofu can change color if stored improperly. Regarding taste, good quality tofu typically has the characteristic rich flavor of soybeans. If the product has an astringent taste, unusual odor, or flavor, caution is advised.

Overall, these are only sensory indicators and cannot definitively confirm whether a piece of tofu contains gypsum. Tofu's color, firmness, and texture also depend on the soybean variety, production process, coagulant, water ratio, and storage conditions. To accurately determine the composition or specific substance content in food, appropriate testing methods are required.

Illustrative photo: Bui Thuy

Tofu is rich in protein, calcium, and iron, benefiting overall health, providing energy, and not significantly increasing estrogen levels in men. With 7-9 g of protein per 100 g, it is an excellent plant-based protein choice. Another advantage of tofu is its virtually cholesterol-free nature, unlike meat.

Tofu contains fats, predominantly polyunsaturated fats. These fats, commonly found in plants and fish, include omega-3 and omega-6 fatty acids, which help regulate cholesterol. According to the American Heart Association, replacing saturated fats with unsaturated fats can reduce the risk of cardiovascular disease. Tofu provides essential amino acids vital for normal bodily functions. Soy protein is a complete protein, supplying sufficient critical amino acids for tissue repair, nutrient transport, and muscle development.

To minimize the risk of purchasing substandard products, consumers should choose tofu from reputable producers and stores with clear origins. For packaged tofu, it is essential to check information about the manufacturer, ingredients, production date, expiration date, and storage conditions. Avoid buying tofu with unusual odors, abnormal colors, sliminess, sourness, or signs of spoilage.

For better control over ingredients, consumers can also make tofu at home using soybeans and appropriate coagulants.

Thuy Quynh