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Olax zeylanica is a green leafy vegetable rich in phenolics and carotenoids and also posses good antioxidant activities.
The optimum extraction conditions for the higher recovery of total phenolics and carotenoids contents for leaves of
Olax zeylanica were developed using response surface methodology. A three-factor inscribed central composite design
(CCD) was used to identify the relationship existing between the response functions (total phenolics and carotenoids)
and the process variables, as well as to determine those conditions that optimized the extraction process of total
phenolics and carotenoids contents of the extracts. The process variables used for the study were concentration (30-
100%), extraction temperature (30-60 °C) and extraction time (30-90 min) on the recovery of total phenolics and
carotenoids. Multiple graphical and numerical optimizations of the experimental data were done to identify the
optimum extraction conditions to achieve the maximum recovery of total phenolics and carotenoids. Optimum
extraction conditions of ethanol concentration, extraction temperature and extraction time for phenolics, were 6.14%,
19.8 °C, and 9.54 min and for carotenoids, the optimum parameters were 100%, 70.2°C and 110.5 min, respectively.
The optimal predicted contents for total phenolics (16.7 mg Gallic Acid Equivalent (GAE)/ g DW) and carotenoids
(6.03 mg/g DW) values in the extracts were agreed with the experimental values obtained with optimum extraction
conditions for each response.
