What can be added to emulsions to prevent oxidation?

• A. Antioxidants
• B. Surfactants
• C. Thickeners
• D. Preservatives

Answer: (A)

Oxidation in emulsions happens when oxygen reacts with unsaturated fats, triggering a chain of radical reactions that lead to rancidity, off-flavors, and spoilage. The way to prevent this is to add antioxidants, substances that interrupt those radical chain reactions. They can donate hydrogen or electrons to neutralize free radicals, or chelate metal ions that would otherwise catalyze oxidation, effectively slowing or stopping the oxidative process. Lipid-soluble antioxidants like tocopherols (vitamin E) reside in the oil phase and protect the fat droplets, while others such as ascorbyl palmitate or synthetic antioxidants like BHT/BHA act similarly to stabilize the emulsion.

Surfactants change interfacial properties to keep the emulsion stable but don’t directly stop oxidation. Thickeners alter viscosity and can influence diffusion and oxygen access, which may affect oxidation rates indirectly, but they don’t prevent oxidation themselves. Preservatives mainly target microbial growth, not chemical degradation from oxidation, though some may have minor antioxidant activity; they are not the primary method for preventing oxidation in emulsions.

So, antioxidants are added to emulsions to prevent oxidation.