What is soy protein made from?

December 17, 2025 •

2 min read

According to the Soy Connection, soy protein is the only plant protein that contains all nine essential amino acids. But what is soy protein made from? The process begins with soybeans, which are transformed through various manufacturing methods into products like isolates, concentrates, and flours.

Quick Summary

Soy protein is derived from soybeans, which undergo a multi-step process including defatting, dehulling, and grinding. The resulting products are soy flour, soy protein concentrates, and highly refined soy protein isolates, each with varying protein levels and uses.

Key Points

Source: Soy protein is exclusively made from soybeans, a versatile legume containing all nine essential amino acids.
Core Process: The primary manufacturing process involves dehulling, defatting the soybeans, and then extracting the protein from the resulting meal.
Three Forms: The main commercial products are soy flour (~50% protein), soy protein concentrate (~70% protein), and soy protein isolate (≥90% protein).
Concentrate Production: This form is created by removing water-soluble carbohydrates from defatted soy flakes using methods like an alcohol or acid wash.
Isolate Production: The most refined form, isolate, is produced by dissolving the protein in an alkaline solution, separating it from fibers, and then precipitating and drying the protein curd.
Flavor Profile: As processing increases, the protein becomes purer and the flavor becomes more neutral, with isolate having the mildest taste.
Functionality: Different forms of soy protein are used in food production for varying applications, from thickening sauces to fortifying nutritional bars.
Health Benefits: A diet including soy protein may help lower cholesterol levels and support muscle health, offering a complete plant-based option.

The Raw Material: From Soybean to Meal

Soy protein manufacturing begins with whole soybeans, a legume native to East Asia. These beans are a natural source of complete protein, meaning they contain all nine essential amino acids. The initial processing steps are critical for preparing the soybeans for protein extraction.

Soybean Pretreatment

The first step involves cleaning the soybeans to remove impurities, followed by heating and dehulling to remove the outer skins and increase protein concentration. The dehulled beans are often rolled into flakes to help extract oil.

Oil Extraction

Oil is typically removed from soybean flakes using solvent extraction, leaving behind a high-protein, defatted soybean meal, known as "white flakes". This defatted meal is the base for various soy protein products.

The Three Main Forms of Soy Protein

Defatted soybean meal is processed into three primary commercial products: soy flour, soy protein concentrate, and soy protein isolate.

1. Soy Flour

Soy flour is the simplest form, made by grinding defatted flakes into a powder. It has a protein content of about 50%, contains fiber and carbohydrates, and is used in baked goods. It has a distinct soy flavor.

2. Soy Protein Concentrate

Produced by removing water-soluble carbohydrates using washes like aqueous alcohol or dilute acid. Soy protein concentrate has around 70% protein, retains most fiber, and is used in cereals, baked goods, and meat products for nutrition and texture, with a milder flavor than soy flour.

3. Soy Protein Isolate

Soy protein isolate is the most refined form, containing at least 90% protein. The process involves dissolving protein from defatted flakes in an alkaline solution, separating it from fibers, precipitating it with acid, then washing and drying the protein. It has a neutral flavor and is highly digestible, used in protein powders and nutritional bars.

Functional and Nutritional Differences

Processing methods impact the nutritional content, functional properties, and taste of each soy protein product, leading to different uses in the food industry.

Comparison of Soy Protein Products


Feature	Soy Flour	Soy Protein Concentrate	Soy Protein Isolate
Protein Content	~50%	~70%	≥90%
Fiber	High	Retained	Low / Removed
Carbohydrates	Present	Low	Removed
Fat	Can be full-fat or defatted	Low	Very Low
Flavor	Stronger, "beany" taste	Mild	Neutral
Processing Level	Low	Medium	High
Applications	Baked goods, sauces	Meat extensions, cereals	Protein shakes, nutritional bars

Conclusion: A Versatile Ingredient from a Humble Bean

Soy protein originates from soybeans and is transformed through industrial processes into three distinct products: flour, concentrate, and isolate, each offering different nutrition, flavor, and functionality. This versatility makes soy protein a valuable ingredient for various applications, providing a complete plant-based protein source.

For more detailed information on soybean processing, the Food and Agriculture Organization of the United Nations offers extensive resources: Technology of production of edible flours and protein products from soybeans.

Frequently Asked Questions

The starting ingredient for soy protein is the soybean, a legume that is dehulled and defatted before processing.

Soy protein isolate is the most refined form, with at least 90% protein, as most of the carbohydrates and fats are removed. Soy protein concentrate has a lower protein content of about 70% and retains more of the bean's natural fiber.

Yes, soy protein is considered a complete protein because it contains all nine essential amino acids that the human body needs for growth and repair.

The process involves dissolving the protein from defatted flakes in an alkaline solution, separating the protein from fibers, precipitating it with acid, and then washing and drying the resulting protein curd into powder.

Soy protein concentrate is often used as an ingredient in breakfast cereals, baked goods, and various meat products to enhance their nutritional profile and texture.

The flavor depends on the level of processing. Highly refined soy protein isolate has a neutral flavor, whereas less processed forms like soy flour can have a more noticeable 'beany' taste.

As a plant-based protein source derived from legumes, soy is often highlighted for its potential to be a more sustainable and environmentally friendly protein alternative compared to some animal protein sources.

Yes, as a complete protein source, soy protein is effective for muscle building and repair, similar to animal-based proteins like whey.