Storage stability is a crucial factor in evaluating ice cream quality, involving aspects such as texture, structure, flavor, and color. While not a conventional ingredient, the addition of magnesium hydroxide can indeed have the following effects in certain formulations:
1. Inhibiting Protein Denaturation and Precipitation:
During long-term freezing or repeated freeze-thaw cycles, milk proteins in ice cream may undergo denaturation, aggregation, and precipitation due to the acidic environment, manifesting as:
- Increased roughness
- Whey separation
- Unstable ice crystal structure
As a weakly alkaline substance, magnesium hydroxide can appropriately adjust the pH of the system, stabilize the milk protein structure, thereby slowing down protein aggregation and extending the structural stability period.
2. Maintaining Freeze-Thaw Structural Integrity:
Repeated freeze-thaw cycles can damage the microstructure of ice cream, leading to:
- Ice crystal growth
- Air loss
- Phase separation
Magnesium hydroxide can indirectly enhance freeze-thaw resistance through two mechanisms:
- pH regulation → Protecting the emulsified structure
- Formation of weak complexes with milk proteins or polysaccharides → Increasing system viscosity and water retention
This mechanism of action is similar to that of certain mineral salts (such as sodium phosphate and calcium citrate), but magnesium hydroxide is milder and has lower sensitivity concerns.
3. Inhibiting Oxidation Reactions and Extending Flavor Shelf Life:
Milk fat and flavorings in ice cream are prone to oxidation, especially during long-term storage, resulting in “off-flavors” or flavor loss.
The alkaline properties of magnesium hydroxide can:
- Neutralize acidic oxidation products (such as free fatty acids)
- Reduce the rate of oxidation chain reactions
Although it cannot completely replace antioxidants, it serves as a mild and low-cost “oxidation barrier” in functional ice cream.
4. Improving Anti-Caking Properties (Dry Storage of Ice Cream Powder):
For ice cream powder products, caking is a major problem, especially under high humidity storage conditions.
Magnesium hydroxide possesses a certain ability to adsorb moisture and prevent caking, and can be used as an anti-caking agent:
- Maintaining powder flowability
- Preventing component segregation or premature reactions
This also applies to “instant” cold beverage powder packets.