Optimization of Conjugated Linoleic Acid (CLA) Synthesis Conditions Applying it in Milk Enrichment

Abstract

In present study, linoleic acid from sunflower oil and propylene glycol as solvent were used to synthesize conjugated linoleic acid (CLA), and the response surface methodology (RSM) was applied to optimize the process. The results showed that the propylene glycol as solvent and reaction time were found to have positive influence on the response, but the high reaction temperature especially at high solvent levels and reaction time, has led to a reduction in the production of CLA. Solvent content of 6.25 mL, a temperature of 100 °C and a time of 140 min were found to be the optimal conditions in the isomerization for the production of cis9-trans11 and trans10-cis12 CLA isomers. In the next step, the produced CLA were concentrated and purified and used for the enrichment of skim milk. Then, qualitative characteristics of milk including pH, peroxide value, sensory properties and CLA retention during storage of enriched milk in the 5 °C were investigated for 90 days. There was no significant (p >0.05) difference between the control and treated samples for one month after storage (p >0.05), but with increasing storage time up to 60 and then 90 days the differences increased (p <0.05). According to the results, the level of remaining CLA in milk, as well as pH decreased over time, but the peroxide value of the samples was increased.

Keywords

• alkali isomerization
• conjugated linoleic acid
• milk enrichment
• propylene glycol
• response surface methodology