Optimisation and Characterisation of Lipase-Catalysed Synthesis of a Kojic Monooleate Ester in a Solvent-Free System by Response Surface Methodology

• Published in: PloS one 2015-12, Vol.10 (12), p.e0144664-e0144664
• Main Authors: Jumbri, Khairulazhar, Al-Haniff Rozy, Mohd Fahruddin, Ashari, Siti Efliza, Mohamad, Rosfarizan, Basri, Mahiran, Fard Masoumi, Hamid Reza
• Format: Article
• Language: English
• Subjects: Acids; Browning; Catalysis; Chemical properties; Chemical synthesis; Design optimization; Enzymatic synthesis; Enzymes; Esterification; Esters; Esters - chemical synthesis; Fatty acids; Food industry; Kojic acid; Lipase; Lipase - chemistry; Mathematical models; Methods; Oleic acid; Oleic Acid - chemistry; Production processes; Pyrones - chemistry; Reaction time; Response surface methodology; Response surfaces; Science; Skin care products; Solvents; Statistical analysis; Substrates; Temperature; Temperature effects; Tyrosinase; Yield
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0144664

Kojic acid is widely used to inhibit the browning effect of tyrosinase in cosmetic and food industries. In this work, synthesis of kojic monooleate ester (KMO) was carried out using lipase-catalysed esterification of kojic acid and oleic acid in a solvent-free system. Response Surface Methodology (RSM) based on central composite rotatable design (CCRD) was used to optimise the main important reaction variables, such as enzyme amount, reaction temperature, substrate molar ratio, and reaction time along with immobilised lipase from Candida Antarctica (Novozym 435) as a biocatalyst. The RSM data indicated that the reaction temperature was less significant in comparison to other factors for the production of a KMO ester. By using this statistical analysis, a quadratic model was developed in order to correlate the preparation variable to the response (reaction yield). The optimum conditions for the enzymatic synthesis of KMO were as follows: an enzyme amount of 2.0 wt%, reaction temperature of 83.69°C, substrate molar ratio of 1:2.37 (mmole kojic acid:oleic acid) and a reaction time of 300.0 min. Under these conditions, the actual yield percentage obtained was 42.09%, which is comparably well with the maximum predicted value of 44.46%. Under the optimal conditions, Novozym 435 could be reused for 5 cycles for KMO production percentage yield of at least 40%. The results demonstrated that statistical analysis using RSM can be used efficiently to optimise the production of a KMO ester. Moreover, the optimum conditions obtained can be applied to scale-up the process and minimise the cost.