Emulsifying salts primarily function by solubilizing calcium phosphate and hydrating casein proteins during the production of processed cheese, resulting in a more stable product with improved functional properties.
Here's a breakdown of how this works:
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The Problem: Natural cheeses contain calcium phosphate, which forms a network within the cheese matrix and can lead to a firm, often brittle, texture. When heated, these cheeses can separate into a grainy mass of solid fat and protein and watery whey.
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The Solution: Emulsifying Salts: Emulsifying salts, typically phosphate or citrate-based, address this issue through two primary mechanisms:
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Calcium Phosphate Solubilization: They bind to calcium, effectively removing it from the calcium phosphate network. This weakens the protein matrix and disrupts the undesirable structure that causes separation upon heating. The calcium is sequestered by the emulsifying salts.
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Casein Hydration and Dispersion: By removing calcium, the casein proteins (the primary proteins in cheese) become more hydrated and dispersed. Hydrated casein proteins contribute to a smoother, more homogenous texture. The emulsifying salts increase the negative charge on the casein micelles, leading to increased repulsion and therefore better dispersion.
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Specific Salts and Their Effects:
- Phosphates (e.g., Sodium Tripolyphosphate (STPP), Sodium Hexametaphosphate (SHMP)): These are common emulsifying salts. They solubilize calcium phosphate effectively and contribute to a smooth, spreadable texture. STPP can also help to increase the pH.
- Citrates (e.g., Sodium Citrate): While also acting as emulsifiers, citrates often have a milder effect compared to phosphates. They tend to produce a slightly softer texture.
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The Result: The overall impact is a processed cheese product that:
- Melts smoothly without separation: The solubilized calcium and hydrated casein prevent the cheese from breaking down into its constituent parts upon heating.
- Has a desirable texture: The texture can be controlled by the type and amount of emulsifying salt used, ranging from firm and sliceable to soft and spreadable.
- Is shelf-stable: The altered protein structure and calcium management contribute to longer shelf life.
In short, emulsifying salts disrupt the calcium phosphate network in cheese, hydrate and disperse casein proteins, and create a stable, homogenous product with desirable melting and textural properties.
