Preparation and Properties of Lactic Acid-based Modified Carboxylic Surfactant

Acyl lactylates are a class of nitrogen-free surfactants derived from natural and biorenewable resources by reacting lactic acid with fatty acid. Lactylates are well known in food industry and in personal care applications as they function as viscosity builders, emulsifiers, foam boosters, stabilizers and can also be used as secondary surfactants. In present work, we studied the synthesis methodology of stearoyl lactylates (SL) using two different routes. SL was synthesized as condensation product of lactic acid with stearic acid by base-catalyzed direct esterification method under reduced pressure, while the other protocol involved the esterification of lactic acid using acid chloride as intermediate. The resulting products after subsequent purification were neutralized with alkali to prepare their sodium salts, sodium stearoyl lactylates (SSL). The synthesized lactylates and their salts were characterized for their various performance properties such as surface tension, pH and hydrolysis rate, emulsifying power and wetting behavior in relation to conventional surfactant having same hydrophobic chain length, sodium stearate (SS).