Does Boiling Soya Chunks Reduce Antinutrients?

January 6, 2026 •

3 min read

Boiling soya chunks is a common preparation method, and numerous studies confirm that heat treatment significantly reduces the presence of antinutrients in soy products. These naturally occurring plant compounds can interfere with nutrient absorption, making proper preparation a key factor in maximizing the health benefits of soya chunks.

Quick Summary

This article explores the effects of boiling on the antinutrient content of soya chunks, detailing how heat-sensitive and water-soluble compounds are reduced. It explains why this simple cooking step improves digestibility and nutritional value for a healthier meal.

Key Points

Boiling reduces antinutrients: Heat treatment effectively deactivates heat-sensitive compounds like trypsin inhibitors and lectins found in soya chunks.
Soaking and boiling is best: Combining soaking with boiling enhances the removal of antinutrients, including water-soluble tannins and phytates, which leach into the cooking water.
Discard the water: Always discard the water used for soaking and boiling, as it contains the leached-out antinutrients.
Improved digestibility: Removing antinutrients makes the protein in soya chunks more bioavailable and improves overall digestion.
Phytic acid needs extra help: While some phytates are reduced by boiling, more significant reduction requires soaking or other methods like fermentation.
Final product is safe: Properly cooked soya chunks are safe and highly nutritious, debunking common misinformation about their antinutrient content.

Understanding Antinutrients in Soybeans

Soya chunks, a popular plant-based protein source, are made from defatted soy flour and contain several antinutrients, which are natural compounds that interfere with the absorption of essential nutrients. While these compounds are a plant's natural defense mechanism, they can be mitigated through proper cooking. The primary antinutrients found in soybeans include:

Trypsin Inhibitors: These are proteins that block the action of trypsin, a digestive enzyme, and can reduce protein digestibility.
Phytates (Phytic Acid): A common antinutrient in seeds, grains, and legumes, phytic acid can bind to minerals like iron, zinc, and calcium, reducing their bioavailability.
Lectins (Hemagglutinins): These carbohydrate-binding proteins can affect the intestinal lining and interfere with nutrient absorption.
Tannins: Found mainly in the seed coat, tannins are polyphenolic compounds that can decrease protein quality and interfere with mineral absorption.

How Boiling Reduces Antinutrients

Boiling is an effective thermal treatment for significantly reducing many of the antinutrients in soya chunks. The process works in a couple of key ways: heat denaturation and leaching into the cooking water.

Heat Denaturation of Trypsin Inhibitors and Lectins

Heat denatures proteins like trypsin inhibitors, inactivating them. Similarly, most lectins are deactivated by heat, though some are more resistant. Boiling is essential for destroying these heat-sensitive antinutrients. Research indicates proper cooking substantially reduces trypsin inhibitor activity.

Leaching of Water-Soluble Antinutrients

Water-soluble antinutrients, such as tannins and some phytates, dissolve and leach into the cooking water during boiling and soaking. Discarding this water after boiling and squeezing the chunks helps remove these compounds. Soaking and boiling together are highly effective at reducing tannins and other soluble antinutrients.

The Impact on Phytic Acid

Boiling offers moderate reduction of phytic acid. A combination of soaking, boiling, or fermentation is more effective. Studies suggest boiling for 60 minutes yields maximal phytic acid reduction in soybeans. Home cooks can minimize phytates and improve mineral absorption by soaking before boiling and discarding the water. Industrial processing also reduces phytate levels. Phytic acid also offers beneficial properties.

The Role of Soaking and Other Methods

For optimal antinutrient reduction, a multi-step approach including soaking is recommended. Soaking activates the enzyme phytase, which begins to break down phytic acid, but it doesn't deactivate heat-sensitive antinutrients like lectins, which require cooking.

Combining soaking and boiling is a highly effective method. Soaking leaches water-soluble compounds, while boiling denatures heat-sensitive ones. This not only reduces antinutrients but also improves the texture and digestibility of soya chunks. Squeezing out the water after boiling is crucial to remove the leached antinutrients. This process enhances the bioavailability of minerals like iron and zinc.

Comparison of Preparation Methods


Feature	Boiling Alone	Soaking & Boiling	Industrial Processing	Fermentation
Trypsin Inhibitor Reduction	Very High	Very High	Nearly Complete	High
Tannin Reduction	High	Very High	Complete	High
Phytate Reduction	Moderate	Moderate to High	High	Very High
Lectins Deactivation	High	High	Very High	High
Required Time	Short (10-15 min)	Medium (1-2 hours)	Varies	Long (24+ hours)
Technique Complexity	Low	Low	High	Medium
Final Nutrient Bioavailability	Good	Better	Excellent	Excellent

Conclusion: The Final Word on Soya Chunks and Antinutrients

Boiling soya chunks is effective in significantly reducing antinutrient levels, particularly heat-sensitive trypsin inhibitors and water-soluble tannins. While soaking is helpful for reducing phytic acid, boiling is a critical step in the preparation process. The recommended practice for home cooks is to soak the soya chunks, boil them, and then discard and squeeze out the water to maximize antinutrient removal. This simple technique enhances the digestibility and nutritional value of soya chunks. By following these steps, you can confidently enjoy this protein-rich food.

For more detailed scientific information on the effect of thermal treatments on antinutrients in soybeans, see this study: Effect of thermal treatments on anti-nutritional factors and antioxidant capabilities in yellow soybeans and green-cotyledon small black soybeans

Frequently Asked Questions

Antinutrients are natural compounds in plants, such as soybeans, that interfere with nutrient absorption. In soya chunks, these include trypsin inhibitors, lectins, and phytates, which can hinder the digestion of protein and the absorption of essential minerals like iron and zinc.

No, simply soaking in hot water is not sufficient. While soaking helps to rehydrate the chunks and can leach out some water-soluble antinutrients, it is boiling that provides the necessary high temperature to deactivate heat-sensitive antinutrients like trypsin inhibitors and lectins.

Yes, squeezing the water out is a critical step. The process of soaking and boiling causes antinutrients to leach into the water. By squeezing and discarding this water, you ensure that these compounds are removed from the food.

No, boiling does not significantly reduce the protein content of soya chunks. It primarily deactivates antinutrients and improves protein digestibility, making the protein more available for your body to absorb.

Boiling for about 10-15 minutes is a common and effective practice for reducing most antinutrients. Soaking the chunks beforehand can make this process even more efficient.

Fermentation is another highly effective method for reducing antinutrients, especially phytates. However, it is a much longer and more complex process. For preparing soya chunks for a meal, soaking and boiling is a simpler and quicker method that yields excellent results.

Consuming uncooked or improperly prepared soya products containing high levels of antinutrients can lead to issues with nutrient absorption and digestion. However, with proper preparation methods like boiling, the levels are significantly reduced, and the chunks become safe and healthy to eat.