Exopolysaccharides (EPS) are high-molecular-weight polysaccharides secreted by microorganisms into their surrounding environment. They play critical roles in various biological functions, including biofilm formation, cell protection, and intercellular communication. In food systems, EPS are particularly valued for their functional properties, which can enhance texture, stability, and flavor. Below is a discussion of various types of EPS produced by microorganisms, examples, and their applications in food systems.

### Types of Exopolysaccharides and Their Sources

1. **Dextran**:

- **Source**: Produced by *Leuconostoc mesenteroides*.

- **Use**: Commonly used as a thickening agent, stabilizer, and emulsifier in food products like sauces, salad dressings, and dairy products. It can improve mouthfeel and prevent syneresis in gels.

2. **Xanthan Gum**:

- **Source**: Produced by *Xanthomonas campestris*.

- **Use**: Widely used in gluten-free baking, salad dressings, and sauces due to its thickening and stabilizing properties. Xanthan gum can also improve the texture and viscosity of beverages and dairy products.

3. **Gellan Gum**:

- **Source**: Produced by *Sphingomonas elodea*.

- **Use**: Utilized as a gelling agent in jellies, desserts, and yogurt. Gellan gum can form firm gels at low concentrations and can be tailored to create a range of textures.

4. **Guar Gum**:

- **Source**: Derived from the guar bean (*Cyamopsis tetragonoloba*).

- **Use**: Employed as a thickening agent in various food applications, including baked goods, dairy products, and sauces. It enhances moisture retention and improves the texture of gluten-free products.

5. **Alginate**:

- **Source**: Extracted from brown seaweeds (e.g., *Laminaria* species).

- **Use**: Commonly used in the food industry as a thickening and gelling agent. Alginate is also utilized in encapsulation technologies for flavor and probiotic delivery in food products.

6. **Carrageenan**:

- **Source**: Extracted from red seaweeds (e.g., *Chondrus crispus*).

- **Use**: Used for thickening and stabilizing dairy products, plant-based milks, and meat products. Carrageenan can also enhance texture and mouthfeel in various applications.

### Functional Properties in Food Systems

- **Thickening and Gelling**: Many EPS, like xanthan and gellan gums, provide thickening and gelling properties, enhancing product texture and stability.

- **Emulsification**: EPS can act as emulsifiers, helping to stabilize oil-in-water emulsions, which is critical in dressings and sauces.

- **Stabilization**: They help prevent phase separation and improve the shelf life of products by stabilizing dispersions.

- **Texture Modification**: EPS can alter the mouthfeel and overall sensory properties of food, contributing to consumer satisfaction.

- **Prebiotic Effects**: Some EPS can act as prebiotics, promoting the growth of beneficial gut microbiota, which can be advantageous for health-focused food products.

### Conclusion

The use of exopolysaccharides produced by microorganisms in food systems is diverse and impactful. Their unique functional properties make them valuable ingredients in improving food texture, stability, and shelf life. As consumer demand for clean-label and natural ingredients increases, the utilization of EPS from microbial sources is likely to expand in various food applications.