Salt Content and Functional Challenges in Meat Products
Meat products typically contain 2%–3% salt (NaCl). In the presence of salt, soluble soybean protein tends to lose solubility and precipitate, which negatively affects:
- Product texture and mouthfeel
- Protein gelation performance
- Emulsification stability
As a result, functional soybean protein concentrates used in meat systems must exhibit strong salt tolerance to maintain solubility and functional performance under high-ionic-strength conditions.
Definition of Salt Tolerance Index
What Is the Salt Tolerance Index?
The Salt Tolerance Index (STI) refers to the ratio of soluble nitrogen content to total nitrogen content of functional soybean protein under saline conditions. It reflects the nitrogen solubility index (NSI) of protein in the presence of salt and serves as a key indicator of salt resistance.
Calculation formula:
Salt Tolerance Index (%) = 100 × [Soluble nitrogen content (%) / Total nitrogen content (%)]
Determination Method of Salt Tolerance Index
The salt tolerance index is determined using the following procedure:
- Add 0.75 g NaCl to a 500 mL conical flask and dissolve it in 150 mL distilled water.
- Transfer the salt solution into a mixer, add 5 g soybean protein, and homogenize at 7000 rpm for 5 minutes.
- Pour the protein solution back into a 500 mL conical flask. Rinse the mixer with 50 mL distilled water and add it to the flask.
- Shake the mixture at 150 rpm for 2 hours.
- Transfer the solution into a 250 mL volumetric flask and make up to volume.
- Transfer 50 mL of the solution into a centrifuge tube and centrifuge at 1500 rpm for 10 minutes.
- Filter the supernatant through rapid filter paper.
- Determine the protein (nitrogen) content of the filtrate using the Kjeldahl method.
The functional soybean protein concentrate described herein exhibits excellent salt tolerance, with a salt tolerance index ranging from 30% to 80%.
Role of Emulsifiers in Improving Meat Product Performance
Function of Sucrose Ester and Succinic Acid Monoglyceride
Sucrose ester and succinic acid monoglyceride are both nonionic surfactants with excellent:
- Emulsifying properties
- Dispersing capacity
- Solubilization ability
- Wetting performance
When incorporated into protein systems, these emulsifiers effectively enhance the water-holding capacity, elasticity, and structural stability of meat products.
Technical Advantages of the Present Invention
The present invention provides a processing method for functional soybean protein concentrate using:
- Alcohol-extracted soybean protein concentrate, or
- Soybean protein curd generated during alcohol extraction
Key Benefits
- Improved protein solubility
- Enhanced oil and water retention
- Strong salt tolerance
- Light color and clean flavor
The resulting protein ingredient can be used in meat products to partially replace soy protein isolate (SPI), thereby reducing formulation costs without compromising product quality.
Performance Characteristics of the Functional Soybean Protein Concentrate
The functional soybean protein concentrate prepared using this technology demonstrates:
- NSI: 50%–80%
- Salt tolerance index: 30%–80%
- Oil and water retention ratio: ≥ 1:5:5
- Light color and low beany flavor
These properties enable broad application in meat products and other food systems requiring high functional stability.
Detailed Embodiments
Example 1
Soybean protein concentrate curd obtained via alcohol extraction is added to a dissolving tank. 15× water is added and mixed for 20 minutes at 60 °C. The pH is adjusted to 8.0 with sodium hydroxide and stirred for 20 minutes. Phospholipids and 0.5% sucrose ester (protein dry basis) are added and mixed thoroughly.
The protein solution undergoes UHT treatment at 140 °C for 15 seconds, followed by spray drying (inlet 160 °C, outlet 80 °C).
Results:
- Protein content: 70%
- NSI: 50%
- Salt tolerance index: 46%
- Oil and water retention: 1:5.2:5.4
Example 2
Soybean protein concentrate curd is mixed with 6× water at 50 °C for 10 minutes. The pH is adjusted to 7.5. After UHT treatment at 130 °C for 40 seconds, phospholipid and 0.5% sucrose ester are added, followed by spray drying.
Results:
- Protein content: 75%
- NSI: 80%
- Salt tolerance index: 75%
- Oil and water retention: 1:5.5:5.9
Example 3
Commercial ≥80-mesh soybean protein concentrate is processed with 10× water at 60 °C, pH adjusted to 7.5, and UHT-treated at 130 °C. 0.2% succinic acid monoglyceride is added before spray drying. A 0.1% phospholipid coating is applied via fluidized bed.
Results:
- Protein content: 71%
- NSI: 61%
- Salt tolerance index: 65%
- Oil and water retention: 1:5.2:5.5
Example 4
Commercial soybean protein concentrate is processed with 12.5× water, pH adjusted to 8.0, and UHT-treated at 150 °C for 30 seconds. Phospholipid and succinic acid monoglyceride are added before spray drying.
Results:
- Protein content: 70%
- NSI: 75%
- Salt tolerance index: 72%
- Oil and water retention: ≥ 1:5:5
Example 5
Commercial soybean protein concentrate is processed with 10× water, pH adjusted to 8.0, and UHT-treated at 150 °C for 15 seconds. A composite emulsifier system (phospholipid, sucrose ester, and succinic acid monoglyceride) is added before spray drying.
Results:
- Protein content: 72%
- NSI: 78%
- Salt tolerance index: 80%
- Oil and water retention: 1:5.6:5.8
Industrial Application and Cost Advantages
By using alcohol-extracted soybean protein concentrate or protein curd as raw materials, this invention provides a cost-effective route to produce functional soybean protein concentrates with high solubility and strong oil–water retention.
These products can be widely applied in meat processing to replace part of soy protein isolate, significantly reducing production costs while maintaining product quality.Industrial Application and Cost Advantages
Scope and Applicability
The above embodiments illustrate the preparation method of the functional soybean protein concentrate but do not limit the scope of application. Any modifications or variations made within the general technical concept of this invention shall fall within the protection scope of this article
How does the “Alcohol Washing” method improve the quality of Soy Protein Concentrate?
Alcohol washing is a critical refinement step used to increase protein concentration while removing unwanted components. In this process, aqueous ethanol is used to leach out soluble carbohydrates (sugars), ash, and “anti-nutritional” factors from the soybean flakes.
Functional Integrity: By using specific alcohol concentrations and controlled temperatures, the process ensures that the protein remains largely undenatured, preserving its ability to gel, emulsify, and bind water in food applications.
Flavor Improvement: This method effectively removes lipoxidases and volatile compounds that cause the characteristic “beany” taste, resulting in a more neutral flavor profile.
What are the primary “Functional Properties” achieved through this specific preparation process?
The preparation of functional SPC is designed to tailor the protein for specific industrial food uses:
Gelation: When heated, the functional protein forms a resilient gel matrix. This provides the necessary “bite” and structural “chew” required in plant-based meat substitutes and various bakery products.
High Water Binding: The process optimizes the protein’s structure to absorb and retain moisture, which is essential for maintaining juiciness in meat analogs and processed meats.
Emulsification: Functional SPC acts as a bridge between oil and water, creating stable fats-in-water emulsions. This is vital for the texture of sausages, mortadella, and vegan spreads.
