Extraction of lutein/zeaxanthin from Arthrospira Platensis and optimisation of the saponification process using the response surface methodology

This study explores the extraction of lutein and zeaxanthin from Arthrospira Platensis (spirulina), with traditional protocols as a reference and response surface methodology as a tool for optimisation. An enhanced extraction procedure was developed for obtaining higher lutein concentration. The extraction process is further optimised using the central composite method, with the aid of design software tools. Methanol was used as the extracting solvent in a fixed ratio with dry spirulina powder. Saponification and hydrolysis using KOH, water and ethyl acetate/dichloromethane were done for isolating lutein and zeaxanthin from its ester. Ultraviolet–visible spectrophotometry was used for analysing the absorbance of the lutein sample at a wavelength of 445 nm. Using the Response Surface Methodology, trials of various combinations are run for finding optimum conditions of saponification. The major variables were reaction time, reaction temperature and concentration of KOH. Temperature range of 45–75°C, the reaction time of 45–70 min and KOH concentrations ranging from 2% to 10% are observed as the optimum range. The sample is filtered using a PVDF membrane and stored in acetone or isopropyl alcohol.