You are a food scientist in a nutritional supplement manufacturing company. Your

Question

You are a food scientist in a nutritional supplement manufacturing company. Your group is working on developing an oil in water emulsion based drink in which the oil phase is fortified with bioactive compounds such as lycopene, beta carotene and vitamin A. You expect a refrigerated shelf life of 4 weeks. Describe your approach to developing this product. How will you stabilize the emulsion? What is the basis of your emulsifier selection? Which factors do you expect to affect the stability of this emulsion? Discuss which emulsion destabilization mechanism would be dominant and why? How will you delay the emulsion destabilization?

Explanation / Answer

Emulsifiers work by forming physical barriers that keep droplets from coalescing.

**A type of surfactant emulsifiers contain both a hydrophilic (water-loving, or polar) head group and a hydrophobic (oil-loving, or nonpolar) tail.

**Therefore, emulsifiers are attracted to both polar and nonpolar compounds.

**When added to an o/w emulsion, emulsifiers surround the oil droplet with their nonpolar tails extending into the oil, and their polar head groups facing the water.

**In an ideal emulsion, the emulsifier is equally attracted to the water phase and the oil phase.

**If the balance is tipped in either direction, the emulsifier may lose contact with the phase to which it is less attracted, causing the emulsion to break down.

**Different emulsifiers have different HLB values, which can predict their ability to stabilize various kinds of emulsions.

**The HLB scale ranges from 0 to 20, with 10 corresponding to an emulsifier that is equally attracted to water and oil.

**Emulsifiers with HLB values greater than 10 are more hydrophilic and thus better at stabilizing o/w emulsions.

**different oils have different HLB requirements.

**For example, vegetable oil emulsions need an emulsifier with an HLB of 7–8, whereas the required HLB value to form a stable castor oil emulsion is 14.

**By matching the HLB value of the emulsifier with that of the oil, formulators can greatly increase their chances of producing a stable emulsion.

**making microemulsions, which offer greater stability than conventional macroemulsions.

**microemulsions are thermodynamically stable.

**if a temperature change causes an emulsion to break down, a microemulsion will spontaneously reform when the temperature changes back to its original value.

**Macroemulsions require high-intensity mixing. Because microemulsions are a thermodynamically stable end point that a system naturally migrates toward, they generally do not require vigorous mixing.

**multilayer emulsions tend to have better physical stability than single-layer emulsions through fluctuations in pH, ionic strength, temperature, freezing and thawing, and dehydration.

**One of the easiest ways to improve stability is to increase the dispersed water phase to >60%.

**This increases the viscosity of the emulsion due to internal phase packing.

**Using the correct emulsifier and level is also critical.

**It's recommend starting with around 5% total emulsifier and reducing the level to the point of failure to help identify the optimal level.

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