Tofu Containing Gypsum: How to Recognize It and Why It Can Be Harmful to Your Health

Tofu that contains gypsum is often firmer and heavier than tofu made using traditional methods. Eating this type of tofu in large amounts may negatively affect your health.

Tofu, made primarily from soybeans, is a nutritious, inexpensive, and widely available food found in markets and supermarkets across the country. From this humble ingredient, countless delicious dishes can be prepared — from crispy fried tofu and tofu in tomato sauce to tofu stuffed with minced meat. Its versatility and delicate flavor make it a staple in many Asian households.

How Tofu Is Made

Traditionally, tofu is produced from ground soybeans that are cooked, strained, and coagulated to form curds. These curds are then pressed into soft white blocks. To achieve coagulation, producers typically use natural souring agents such as vinegar or fermented tofu water from previous batches.

However, according to Associate Professor Dr. Nguyễn Văn Sức, Head of the Department of Chemical and Food Technology at Ho Chi Minh City University of Technical Education, many modern tofu producers use gypsum (calcium sulfate) instead. Gypsum acts as a fast-setting agent that helps the soy protein curdle and solidify quickly. When used, the tofu mixture forms curds much faster, and the yield of tofu can double compared to traditional methods.

The Problem with Industrial Gypsum

Dr. Sức explained that food-grade gypsum can be used safely in limited quantities, as it is highly purified and can even serve as a minor source of calcium. However, industrial-grade gypsum, which is often cheaper, is not safe for consumption. It contains many impurities such as lead, cadmium, and other heavy metals, which are toxic to the human body.

Frequent consumption of tofu made with low-quality gypsum can damage the digestive system, liver, and kidneys. Over time, toxic accumulation may lead to chronic poisoning and increase the risk of kidney stones and other serious health problems.

Traditional Methods Still Work

According to a veteran tofu maker in Hanoi, who shared insights with VietNamNet, it is completely unnecessary to use gypsum when making tofu. By using natural acids such as vinegar or fermented tofu water, producers can achieve the same curdling effect safely — though the yield may be lower. Unfortunately, driven by profit, many producers opt for industrial gypsum to increase production volume and reduce costs.

How to Identify Safe, High-Quality Tofu

A good, safe tofu should be ivory white, soft, and slightly elastic. It should have the natural fragrance and nutty flavor of soybeans, with a smooth and creamy texture similar to warm soy milk skin.

When buying tofu, pay attention to color, texture, and smell:

• Color: Examine all sides of the tofu. If the edges turn yellow after exposure to air, it may contain gypsum. The more yellow the tofu appears (except for turmeric-seasoned varieties), the more likely it has gypsum added. Fresh tofu should remain pale ivory.
  
  

• Taste: Tofu containing gypsum often has a slightly bitter or astringent taste. If too much filler or gypsum is used, the tofu will feel dense, heavy, and rigid when pressed between fingers.

• Texture: Traditional tofu is soft, light, and tender. In contrast, gypsum-based tofu tends to be heavier and lacks elasticity. Excessive firmness is usually a warning sign.

• Smell: Avoid tofu with an unnaturally strong or artificial aroma, as this may indicate the presence of chemical additives or flavor enhancers.

A Note on Fried Tofu

It is also advisable not to buy pre-fried tofu sold in wet markets. Not only is it difficult to tell whether it contains gypsum, but the frying oil used is often of poor quality and may have been reused many times. Such oils can form harmful compounds that increase the risk of digestive and cardiovascular issues.

In Summary

Tofu remains one of the healthiest and most versatile plant-based foods when prepared properly. However, the growing use of industrial gypsum poses real health risks. For your family’s safety, buy tofu from reputable sources, check its color and texture carefully, and consider making your own tofu at home using traditional, natural coagulants like vinegar or fermented tofu water. Doing so ensures both the purity of flavor and the peace of mind that comes with eating clean, wholesome food.