In industrial applications, DHA algal oil mainly faces three major challenges:

1. Poor Oxidative Stability 

DHA contains six double bonds in its molecular structure, making it highly sensitive to light, oxygen, and heat.Oxidation not only reduces nutritional value but also produces unpleasant fishy off-flavors.

2. Poor Water Dispersibility 

As a hydrophobic substance, algal oil is difficult to uniformly disperse directly in aqueous food systems (e.g., beverages, dairy products), affecting product texture and the uniform distribution of DHA.

3. Characteristic Seaweed Odor 

The inherent algaelike smell of algal oil significantly impacts the sensory quality of end products, becoming a major barrier to its use in many mild-flavor foods.

To address these challenges, constructing stable emulsion systems using appropriate emulsification technologies is the core for the efficient industrial application of DHA algal oil.

Core Emulsification Technologies & Process Parameters

Current emulsion systems for DHA algal oil include conventional emulsions, Pickering emulsions, and multiple emulsions, each with distinct characteristics.

1. Conventional Oil-in-Water (O/W) Emulsions

This is the most basic and widely used emulsion system.

Emulsifier Selection & HLB Value

The Hydrophilic-Lipophilic Balance (HLB) value is a key criterion for emulsifier selection.Studies show that the required HLB value for DHA oil emulsification is approximately 11.3.Combination emulsifiers generally perform better than single emulsifiers.For example:

Distilled monoglycerides : Tween 20 = 42% : 58%

Distilled monoglycerides : Tween 40 = 36% : 64%These combinations have been proven to form stable DHA emulsions.

Key Process Parameters

Emulsification temperature: Usually controlled at around 60 °C, balancing oil melting and emulsifier activity while avoiding accelerated oxidation at high temperatures.

Homogenization conditions: High-pressure homogenization is critical for forming fine, uniform droplets.Studies show homogenization at 60 MPa produces appropriately sized and evenly distributed emulsion droplets.Highspeed shearing (13,000–19,000 rpm) during premix preparation also aids initial dispersion.

Stability optimization: Adding suitable thickeners (e.g., 0.06% xanthan gum) increases the viscosity of the external phase, effectively slowing creaming and coalescence and improving physical stability during storage.

2. Pickering Emulsions: A New Physically Stabilized Technology

Pickering emulsions use solid particles as stabilizers, forming a stronger interfacial film.They show great potential in improving the physical and oxidative stability of DHA algal oil.

Stabilizer Particle Selection & Preparation

Glycated whey protein isolate–chitooligosaccharide (g WPI-COS) complexes

A 2022 study found that WPI-COS complexes prepared at pH 5.0, with a protein concentration of 1.0% and a 1:1 (w/w) ratio, had a particle size of approximately 154.0 nm and formed an extremely dense interfacial layer. The stabilized emulsion droplets were around 40 μm, exhibiting excellent storage stability, thermal stability, and oxidative stability.

Gliadin nanoparticles (GLP) & sodium caseinate nanoparticles (NCP)

A 2020 study compared the two systems and found that NCP-stabilized Pickering emulsions exhibited superior pH and ionic stability, rendering them more suitable for the encapsulation of DHA algal oil.

Core Advantages

The rigid interfacial layer of Pickering emulsions effectively blocks lipids from pro-oxidant contacts and significantly slows DHA release during digestion, enabling intestinal targeted delivery and improved bioavailability.

3. Multiple Emulsions & Microencapsulation