ORIGINAL ARTICLE Ultrasound-assisted microextraction of β, ε-carotene-3, 3′-diol (lutein) from marine microalgae Chlorella salina: effect of different extraction parameters S. Gayathri 1 & S. R. Rajasree Radhika 1 & T. Y. Suman 1 & L. Aranganathan 1 Received: 15 December 2017 /Revised: 19 July 2018 /Accepted: 20 July 2018 # Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract A fast and effective microextraction (ME) technique coupled with ultrasonication (US) was applied for extracting a commercially valuable antioxidant compound lutein, from marine microalgae Chlorella salina (C. salina). The extraction of lutein from C. salina was studied in detail under various operating conditions. Several variables influencing the relative response of the target analyte such as temperature (T = 20–60 °C), time (10–50 min), and frequency (15–55 kHz) were optimized. Results showed maximum yield at temperature 40 °C, extraction time of 30 min duration with 35-kHz frequency. Under optimal conditions, the concentration of lutein was 2.92 ± 0.40 mg/g D.W (dry weight). The results obtained are beneficial for the full utilization of Chlorella biomass, which also indicated that ultrasound-assisted microextraction (US-ME) is a very useful method for extracting lutein from microalgae. Keywords Chlorella salina . Lutein . One variable at a time (OVAT) . Ultrasound-assisted microextraction 1 Introduction Microalgae are the established commercial sources of high- regard chemicals, for instance, lutein, β-carotene, astaxanthin, docosahexaenoic acid, phycobilin pigments, and algal con- centrates, for use in beauty care products. Lutein is a commer- cially available, high-value product. It belongs to the group of the carotenoids and is responsible for their natural yellow to orange color [1]. The carotenoid lutein has potential nutraceu- tical and pharmaceutical applications including prevention and treatment of age-related blindness, cataracts, atheroscle- rosis, and some types of cancers [2–4]. Lutein is very effective in neutralizing the reactive oxygen species, and a high con- centration of lutein in the macula lutea protects against age- related macular degeneration [5–7]. Thus, diets containing lutein may help reduce these health-related problems of the eye [8]. The most typical feature of lutein as well as other carotenoids is the long polyene chain. Such a conjugated double-bond system determines the photochemical properties and chemical reactivity that give the basic biological functions of carotenoids, such as antioxidant activities [9]. It is also used for nutraceutical and pharmaceutical applications. Because of significant useful applications of lutein, extraction of β- carotene has been a topic of interest for many researchers and a lot of efforts have been made for extracting these pig- ments from various raw materials. Different extraction tech- niques such as simple solvent extraction, supercritical fluid extraction, and microwave-assisted extraction have been used with limited success. Application of ultrasound for the intensification of the extrac- tion is becoming popular and ultrasound-assisted extraction (UAE) has been used extensively for enhancing the rate and yield of extraction of different compounds from plant materials [10]. Recent studies also show that ultrasonic treatment improves the efficiency of liquid-liquid extraction [ 11, 12], aqueous two-phase extraction [13], and enzymatic extraction [14] etc. In recent years, with the developing interest in miniaturization in analytical chemistry for solvent and sample savings, some newer miniatur- ized approaches to liquid extraction have been reported. Microextraction techniques are gaining importance since they * S. R. Rajasree Radhika radhiin@gmail.com 1 Centre for Ocean research, Sathyabama Institute of Science and Technology, Sathyabama University, Jeppiaar Nagar, Rajiv Gandhi Road, Chennai 600119, India Biomass Conversion and Biorefinery https://doi.org/10.1007/s13399-018-0331-9