Influence of the hydrophilic head size and hydrophobic tail length of surfactants on the ability of micelles to stabilize citral.
BACKGROUND
Surfactant-made micelles can control the rate of chemical degradation of poorly water-soluble food flavors. To evaluate how the molecular structure of surfactant has an influence on the chemical decomposition rate of citral, micelles were prepared with polyoxyethylene alkyl ether-type surfactants that had similar molecular structures but various hydrophilic head sizes and hydrophobic tail lengths.


RESULTS
At a critical 20× micelle concentration of surfactant, there was no significant difference in the chemical degradation rate of citral in micelles in neutral pH, regardless of the hydrophilic head size or hydrophobic tail length. In an acidic environment, the degradation rate constant of citral generally increased proportionally with increasing hydrophilic head size of surfactant (0.1563 and 0.2217 for surfactants with 23 and 100 oxyethylene units, respectively) but the length of hydrophobic tail did not affect the citral stability. Also, little difference (0.2217 and 0.2265 for surfactant having 100 oxyethylene units with and without Fe(3+) ) in degradation rate constant of citral between simple micellar solution and micellar solution containing iron suggested that iron ions could not accelerate citral degradation in micelles, regardless of the form of iron (Fe(2+) and Fe(3+) ).


CONCLUSIONS
This work concludes that although the concentration of surfactant could be relevant, if its concentration could be controlled in the same manner as the critical micelle concentration, then a polyethylene alkyl ether-type surfactant with a small hydrophilic head could more efficiently stabilize citral at an acidic pH. © 2015 Society of Chemical Industry.
Department of Food Science and Technology, Seoul National University of Science and Technology, Seoul, 01811, Korea.
Chi Rac
CR
Hong
Department of Food Science and Technology, Seoul National University of Science and Technology, Seoul, 01811, Korea.
Sung Joon
SJ
Park
Department of Food Science and Technology, Seoul National University of Science and Technology, Seoul, 01811, Korea.|Department of Interdisciplinary Bio IT Materials, Seoul National University of Science and Technology, Seoul, 01811, Korea.
Seung Jun
SJ
Choi
D000080462:Acyclic Monoterpenes; D005421:Flavoring Agents / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007501:Iron / Q000737:chemistry; D008823:Micelles; D039821:Monoterpenes / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D000080462:Acyclic Monoterpenes; D005421:Flavoring Agents; D008823:Micelles; D039821:Monoterpenes; C495681:Sanonic SS-90; D013501:Surface-Active Agents; D014867:Water; D011092:Polyethylene Glycols; D007501:Iron; C007076:citral
chemical decomposition; citral; micelles; polyoxyethylene alkyl ethers; storage stability