kids encyclopedia robot

Soy protein facts for kids

Kids Encyclopedia Facts
Soybean Pod (48754451708)
Soybean pod

Soy protein is a type of protein that comes from soybeans. It's made from soybean meal after the outer husks are removed and the fat is taken out. These processed soybeans are then turned into three main high-protein products: soy flour, concentrates, and isolates. Soy protein isolate has been used in foods since 1959 because of its helpful properties.

Soy protein is mostly found in special parts of the soybean called "protein bodies," which hold about 60–70% of all the protein. When a soybean starts to grow (germinates), this protein breaks down into amino acids. These amino acids then travel to help the new plant grow. Soybeans also have other active proteins like enzymes. The important storage proteins in soybeans, which are good for people to eat, can be easily taken out using water or salt solutions from soybeans that haven't been heated too much.

History of Soy Protein

Soy protein has been used for its helpful features since 1936. In that year, a chemist named Percy Lavon Julian created the first factory to make industrial-grade soy protein, called "alpha protein." This type of protein was mainly used, and still is, for coating paper, helping the ink stick better.

Julian's factory also made the "soy protein isolate" that Robert Boyer and Frank Calvert used to create an artificial silk. This silk was even used to make a famous suit that Henry Ford wore! The factory eventually made 40 tons of soy protein isolate every day, making it a very successful part of the Glidden company.

During World War II, Glidden sent some of Julian's soy protein to a company called National Foam System Inc. They used it to create "Aero-Foam," which the United States Navy used to fight fires. This foam was often called "bean soup." It was very important for putting out oil and gasoline fires on ships, especially on aircraft carriers, and helped save many lives.

Over the years, different companies bought and merged with the soy protein businesses. In 1958, Central Soya bought Julian's Soy Products Division. Later, in 2003, Central Soya's protein division joined with DuPont's soy protein business, Solae. DuPont fully bought Solae in 2012.

Food-grade soy protein isolate became available to the public on October 2, 1959, when Central Soya opened its Promine D production facility. Another company, Ralston Purina, also started making edible soy isolate and spun soy fiber in 1960. By 1988, PTI (Protein Technologies International), which was part of Ralston Purina, became the world's top maker of isolated soy protein.

What Foods Use Soy Protein?

Soy protein is found in many different foods. You might find it in:

How is Soy Protein Used in Products?

Soy protein isn't just for eating! It has many "functional uses," meaning it helps products work better. For example, soy flour glue is now being used instead of more harmful glues for plywood. This is because it's safer and doesn't contain formaldehyde.

Soy protein is also used to help things mix well (like an emulsifier) and to give them a certain feel or texture. Here are some other ways soy protein is used:

How is Soy Protein Made?

There are different ways to make edible soy protein products.

To make soy protein "isolate," defatted soy flour is mixed with water. The protein is then separated from other parts, like carbohydrates, by changing the pH (how acidic or basic it is). The protein forms a curd, which is then collected and dried.

Soy protein concentrate is made by keeping the soy proteins in place while washing away the soluble carbohydrates and salts from the defatted soybeans. This can be done using alcohol, acids, or hot or cold water.

All these methods result in a product that is about 70% protein. One tonne (about 1,000 kilograms) of defatted soybeans can make about 750 kilograms of soy protein concentrate!

Types of Soy Protein Products

When you see soy protein in foods, it usually comes in three main forms: soy flour, soy protein isolates, and soy protein concentrates.

Soy Protein Isolates

Soy protein isolate is a very pure form of soy protein. It has at least 90% protein after all the moisture is removed. It's made from defatted soy flour, where most of the fats and carbohydrates have been taken out. Because of this, it has a very mild taste and is less likely to cause gas than soy flours.

Soy isolates are mainly used to make meat products feel better in your mouth (improve their texture). They also add more protein, help foods hold moisture, and act as an emulsifier (helping oil and water mix).

Pure soy protein isolate is mostly used by the food industry. You might find it in health stores or the pharmacy section of a supermarket, but it's usually mixed with other ingredients.

Soy Protein Concentrates

Soy protein concentrate is about 70% soy protein. It's basically defatted soy flour with the water-soluble carbohydrates removed. It's made by taking out some of the soluble sugars from soybeans that have had their husks and fat removed.

Soy protein concentrate keeps most of the fiber from the original soybean. It's widely used in many foods, especially in baked goods, breakfast cereals, and some meat products. In meat and poultry, it helps hold water and fat, and it adds more protein while reducing fat.

Soy protein concentrates come in different forms like granules, flour, and spray-dried powders. Because they are easy to digest, they are good for children, pregnant women, and older people. They are also used in pet foods, milk replacements for baby animals, and even for some non-food uses.

Soy Flours

Soy flour is made by grinding soybeans into a fine powder. It comes in a few types:

  • Whole or full-fat: This type still has the natural oils from the soybean.
  • Defatted: The oils have been removed, and it has about 50% protein. It can be made to mix easily with water or not.
  • Lecithinated: This has lecithin added to it.

Since soy flour does not contain gluten, breads made with yeast and soy flour tend to be quite dense.

Soy grits are similar to soy flour, but the soybeans are toasted and broken into larger, coarser pieces.

Kinako is a roasted whole soy flour used in Japanese cuisine. It has been used since at least 1540 CE.

Nutrition in Soy Protein

Soybean protein is called a "complete protein" because it provides all the essential amino acids that humans need to get from their diet. It's very similar to proteins found in other legumes like beans and lentils. Soy protein is also one of the cheapest ways to get protein, which makes it very important for many vegetarians and vegans.

Soy flour itself contains about 50% protein.

How well your body can digest soy foods varies: steamed soybeans are about 65.3% digestible, tofu is 92.7%, soy milk is 92.6%, and soy protein isolate is 93–97% digestible.

Scientists use different ways to measure how good a protein is for nutrition. One common method, recognized by health organizations like the FAO/WHO and FDA, is called the "protein digestibility-corrected amino acid score" (PDCAAS). This method helps measure the true nutritional value of proteins from both animals and plants.

Based on the PDCAAS method, soy protein is considered to have a protein quality similar to animal proteins. For example, egg white has a score of 1.00, soy concentrate is 0.99, beef is 0.92, and isolated soy protein is 0.92. If a protein scores higher than 1.0, it's usually rounded down to 1.0, because it means the protein has more essential amino acids than humans need.

Biological Value

Another way to measure how well a protein is used by the body is the "biological value" scale. This method looks at how much nitrogen (from protein) the body keeps. Soy protein isolate has a biological value of 74. Whole soybeans have a biological value of 96, and soy milk has 91.

How Soy Protein Helps the Soybean Plant Grow

Soy protein is mainly stored in special "protein bodies" within the soybean seed, making up 60% to 70% of the total protein. This protein is vital for the growth of new soybean plants. When the soybean seed starts to germinate (sprout), the stored protein breaks down. The released amino acids then move to where the new seedling is growing, providing the building blocks it needs.

Soybeans also contain active proteins like enzymes. The important storage proteins in the soybean's cotyledon (the first leaves of the seedling), which are good for human nutrition, can be easily taken out using water or salt solutions from soybeans that have been dehulled (husks removed) and defatted (fat removed), and that haven't been heated too much.

Uses of Soy Protein

Textured Soy Protein

Textured soy protein (TSP) is a popular product made from highly soluble defatted soy flour. To make it, the flour is mixed with water to form a dough. This dough is then pushed through a special machine called an extruder, heated, and shaped into different forms like granules, flakes, chunks, or even steak-like pieces. After shaping, it's dried in an oven.

TSP made from soy flour contains 50% soy protein and needs to be soaked in water before use (1 part TSP to 2 parts water). If TSP is made from soy concentrate, it has 70% protein and can soak up more water (1 part TSP to 3 parts water). It can be used as a supplement or a replacement for meat. The way it's made changes the soy protein's structure, giving it a fibrous, spongy texture that feels similar to meat.

TSP can last for over a year if stored dry at room temperature. However, once you add water to it, you should use it right away or keep it in the refrigerator for no more than three days. You can rehydrate it with cold or hot water, and adding a little vinegar or lemon juice can speed up the process.

Soy protein products like TSP are often used as a cheaper way to extend meat and poultry products. Restaurants, stores, and places like school cafeterias often use these "extended" products. While extending meat might slightly change the flavor, it also reduces fat and cholesterol. Vitamins and minerals can be added to soy products to make them as nutritious as animal protein. The protein quality is already quite similar. For over 50 years, textured vegetable protein (a type of TSP) has been used to safely and affordably extend ground beef by up to 30% for hamburgers, without lowering its nutritional value.

See also

Kids robot.svg In Spanish: Proteína de soya para niños

kids search engine
All content from Kiddle encyclopedia articles (including the article images and facts) can be freely used under Attribution-ShareAlike license, unless stated otherwise. Cite this article:
Soy protein Facts for Kids. Kiddle Encyclopedia.