Chemical characterization of polyphenols and volatile fraction of coriander (Coriandrum sativum L.) extracts obtained by subcritical water extraction

• Evaluation of extraction parameters for subcritical water extraction of coriander seeds.
• Chemical characterization of polyphenolic and volatile fraction.
• Improvements in yields of extracted polyphenols and volatile compounds.
• Determination of optimal conditions for maximizing responses.

In this work, coriander (Coriandrum sativum L.) seeds were extracted by subcritical water extraction (SWE) at different temperature (100–200 °C), pressure (30–90 bar) and extraction time (10–30 min), using Box-Behnken experimental design. Polyphenol compounds in obtained extracts were analyzed by HPLC–MS/MS, and 3,4-dimethoxycinnamic acid was dominant compound with the highest yield (942 mg/100 g DW) obtained at 100 °C, 60 bar and 10 min. Chemical profile of volatile compounds was determined by GC–MS. Linalool, which is a dominant compound in coriander essential oil, was the most abundant volatile compound in all extracts obtained at 100 and 150 °C, however, it almost completely degraded at 200 °C. Total extraction yield (Y), polyphenols content (PC) and total volatile compounds (TVC) were response variables in investigated experimental design. Due to satisfactory statistical parameters, applied models for Y and PC represented good approximation of experimental results. Determined SWE conditions which provided maximized PC (1001 mg/100 g DW) were temperature of 100.5 °C, pressure of 87.6 bar and extraction time of 10 min. Even though, TVC could not be optimized by RSM due to disagreement between observed results and second-order polynomial model, it is concluded that essential oil and polyphenol compounds could be co-extracted with a good yield at optimal conditions for PC, as the highest TVC was obtained at 100 °C, 60 bar and 10 min.