Date: 24/11/2020
Projections indicate that in the coming years there will be even greater demand for foods that use soy as one of the main ingredients in their formulations, such as sausages, bread, among others.
A long time ago soy was used mainly for the production of vegetable oils and animal feed. However, in the past few decades, we have observed several food formulations that contain soy-based ingredients.
The public that consumes these products is not restricted to vegetarian/vegan people. Due to the healthy appeal of the grain, soy has already become part of the diet of a large number of consumers.
Some of these soy products are produced in a manufacturing flow, that is, first the extraction of soy oil happens, which generates the ground white soy bran, and then other products are obtained, such as textured soy protein and soy flour defatted.
These products are some of the components of soy that attract the most attention both because of the nutritional value and for their range of functional properties. Whether in the form of isolated, concentrated, textured soy protein or flour, they all integrate a wide variety of formulations.
Therefore, in this blog post, we will discuss further the functional properties and characteristics of soy, as well as some of its diverse applications in the food industry.
Soy and its valuable components
In recent years, soy has become one of the main sources of edible oil and its bran, resulting from oil extraction, can be used for a wide variety of applications in human and animal nutrition.
Soy protein contributes to the formulation of products with valuable characteristics, such as its impressive content of high nutritional quality proteins and its functional properties.
Functional properties of soy
The nutritional value and sensory characteristics have a major impact on the use of soy protein as an ingredient. However, functional properties are also essential to define what type of application the ingredient will be used for.
The functional properties of a protein can be divided into three main types:
Hydrophilic properties
Hydrophilic properties are related to the way that proteins interact with water.
These properties will determine characteristics such as solubility, water retention, adhesiveness, dispersibility, and viscosity.
It is important to evaluate the above-mentioned characteristics, as they are directly related to the texture and flavor of the product.
For example, considering a particular food that has high humidity, such as meat products, the addition of soy proteins favors water retention, preventing the product from drying out and providing the desired viscosity to it.
In addition, the evaluation of protein solubility is essential to determine which food can receive the ingredient. Water-insoluble proteins can contribute to the stability of emulsions, such as salad dressings, for example.
Intermolecular properties
Intermolecular properties are defined as the way in which protein interactions occur with other proteins and components in the food matrix.
These properties relate to the characteristics of precipitation, gelatinization, and paste formation.
Hence, these characteristics are essential for the stability of the products, mainly to acquire the desired texture. This is the case with bakery products, where the interaction between proteins contributes to the formation of dough, stability, and softness.
Surface properties
Surface properties relate to the ability of proteins to unite and form a film between two phases, modifying the texture of the original matrix. This is possible under specific conditions for each protein, such as agitation, temperature, and pH.
As a result, these properties relate to the characteristics of surface tension, emulsification and foaming.
Taking this into consideration, foods that are emulsions or foams, for example, mayonnaise and meringue, need to have stable interactions between proteins, so that the different phases of these products are not separated.
Therefore, it is possible to understand that functional properties are directly related to the physical and sensory properties of foods.
Textured soy protein
Textured soy protein is produced from soybeans that are subjected to a grinding, cooking, and drying process. The soy flours defatted or soy concentrates are mechanically processed by extruders to obtain a meat-like texture when hydrated and cooked.
These products can be obtained from defatted soy particles (flakes and grains) and isolated and/or soy protein concentrates, which are used in order to provide texture and consistency to food, in addition to increasing the protein content of food products when added to formulations.
Textured soy protein is known as “soy meat” and is used in the food industry as an ingredient, ideal for developing products for lactose-intolerant, vegetarian, vegan, and celiac consumers.
Some products that textured soy protein can be applied to:
- Sausages, bologna, salami, hamburgers, pasta, and bread: absorption and water retention due to the formation of hydrogen bonds; mass elasticity due to the formation of disulfide bridges, in gels and oil absorption;
- Mortadella, pates, and sausages: emulsification by the formation and stabilization of emulsions and viscosity due to water retention.
As its name states, textured soy protein is a high-protein ingredient, free of cholesterol, lactose and gluten. Thus, it is a versatile ingredient for application in food products.
Textured soy protein undergoes heat treatment and inactive extrusion of compounds, such as lecithin, phytate, and trypsin inhibitors. Through this treatment, it can provide an increase in its digestibility and bioavailability.
Soy Flours
Soy flours are products obtained by fine milling of hulled soybeans with total fat or defatted flakes made with hulled soybeans.
According to FAO, soy flour is classified according to its lipid content as follows:
- Defatted soy flour: obtained from flakes extracted with solvent (hexane), contains less than 1% oil;
- Whole soy flour: made from hulled soy, it doesn’t have an extraction phase, and contains about 18% to 20% oil;
- Low-fat soy flour: made by adding a bit of oil to defatted soy flour. The lipid content varies according to specifications, generally between 4.5% and 9%. The most common range is between 5% and 6%;
- High-fat soy flour: produced by adding soy oil to defatted flour, usually at the level of 15%;
- Lecithinated soy flour: made by adding soy lecithin to defatted, low-fat or high-fat soy flours in order to increase its dispersibility and provide emulsifying properties. The lecithin content varies according to specifications, usually up to 15%.
Each flour presented in this text is applied for a different purpose. The main uses are: improving the texture and shelf life of bread and other bakery products, stabilizing and emulsifying soups and processed meats, partial replacement of ingredients such as eggs, milk and wheat.
Defatted flours are the most used ones and are classified into two types, as inactive and active, both of which are obtained from ground white soybean meal, derived from the extraction of soybean oil.
Inactive Soy Flour Defatted undergoes a heat treatment that provides enzymatic inactivation. In addition to that, it has properties such as water retention and it is able to stabilize emulsions.
Active Soy Flour Defatted, on the other hand, undergoes a production process that preserves enzymatic activity, and is recommended to be applied to products that are going to be cooked or baked, as this heat treatment will inactivate the enzyme, which can cause and prevent indigestion and heartburn in consumers.
In addition, the active soy flour defatted also has properties such as water retention, emulsions stabilization, promotes bleaching of flours, and can be used in bakery products, including gluten-free products.
Main applications of textured soy protein and soy flour in food
The main characteristics of Soy Protein that will contribute to its use in the food industry are:
- High nutritional value
- Extensor functions
- Contribution to texture, liquid retention and emulsion stability of the final product.
Therefore, read about the main used of textured soy protein and soy flour in foods:
Meat products
In products such as hamburgers and meatballs, texturized soy protein and soy flour defatted can be used, because of the high degree of hydration of these products. Usually, the proportion of 18% protein in the hydrated form is the ideal one to obtain a satisfactory texture.
In a study with textured soy protein and textured soy protein concentrate, satisfactory results were obtained considering hydration (82.33% and 96.08%) of meat products. Soy products, when used in meat products, have positive effects in terms of improving sensory properties, ensuring stable production and efficiency for large-scale production.
Bakery products, cereals, pasta, and chocolates
Proteins and soy flour can be added as ingredients in baked products, cereals, and pasta. This happens for economic, functional, and nutritional reasons, due to the price and compatibility of vegetable fiber with most bakery products.
Textured soy protein can be used as an ingredient in the production of snacks, such as Brazilian coxinha, kebab, croquette, among others.
Active soy flour defatted is the most widely used soy ingredient in bakery products, pasta, and chocolates, as these are products that have undergone thermal processes for their preparation, so the enzyme present in this flour will be inactivated, thus not causing digestive problems for the consumer.
Active soy flour defatted can be used as a partial substitute for milk and eggs. It can also be applied to replace wheat flour in gluten-free products.
The Food Science Nutrition study on gluten-free bread supplemented with soy flour showed an increase in protein content from 9.8% to 12.9% compared to the control samples, along with an increase in fat (3.3% to 4.1%) and fiber (0.29% to 0.38%). In addition, supplementation in bread scored well in sensory evaluation and demonstrated desirable characteristics related to the texture of the product.
Conclusion
Nowadays, due to the combination of balanced nutritional composition and excellent functional properties, soy-based products are becoming increasingly essential in the formulation of many products, improving aspects such as texture, liquid retention and emulsion estability.
Therefore, ingredients such as textured soy protein, with and without poultry skin, and inactive and active defatted soy flour, have been used in foods such as meat products, bakery products, cereals, pasta, and chocolates.
In fact, projections indicate that the use of the raw material will become higher in the coming years, enabling the development of new products and increasing the potential of soy-based ingredients.
In addition, all the characteristics discussed here open up new possibilities for creating new products that have textured soy protein or soy flour as a base.
