Double interface formulation for improved α-tocopherol stabilisation in dehydration of emulsions

Area of Science:

• Food science and technology
• Materials science
• Nutrient encapsulation

Background:

• Hydrophobic nutrients can be encapsulated using freeze-drying of oil-in-water emulsions with glass-forming materials.
• Polyelectrolyte layers on protein-stabilized droplets can enhance protection against external stresses.

Purpose of the Study:

• To investigate the efficacy of layer-by-layer (LBL) and single-layer (SL) delivery systems for encapsulating olive oil with alpha-tocopherol.
• To evaluate the stability of alpha-tocopherol in freeze-dried emulsions under varying water activity and storage conditions.

Main Methods:

• Preparation of soy and whey protein-trehalose emulsions with and without ι-carrageenan (LBL vs. SL).
• Encapsulation of olive oil and alpha-tocopherol, followed by freezing and freeze-drying at pH 3.
• Assessment of alpha-tocopherol stability at 0 and 0.33 water activity (aw) during storage at 55°C.

Main Results:

• Alpha-tocopherol loss occurred in soy protein-stabilized SL systems at 0.33 aw, coinciding with trehalose crystallization.
• Alpha-tocopherol stability was maintained in soy protein-stabilized LBL and whey protein-stabilized LBL and SL systems under all tested conditions.
• Trehalose crystallization was identified as a cause of structural loss in the emulsions.

Conclusions:

• Component sugar crystallization contributes to the degradation of sensitive compounds within emulsions.
• Layer-by-layer (LBL) formulations significantly enhance the stability of encapsulated nutrients compared to single-layer systems.