*3.5. Fatty Acid Analysis*

Heptadecanoic acid (17:0) was added as an internal standard to the chloroform phase of the extracts obtained as specified above and the samples were transmethylated according to [38]. Methyl esters were extracted with *n*-hexane and immediately subjected to GC-MS analysis with an Agilent 7890 gas chromatograph equipped with DB-23 capillary column (Ser. No. US8897617H, 60 m × 0.25 mm, containing a grafted (50% cyanopropyl)-methylpolysiloxane polar liquid phase as a 0.25 ΐm-thick film) coupled with Agilent 5975 ʈ mass-selective detector (Agilent, Santa Clara, CA, USA). The fatty acid methyl esters (FAME) were separated under the following conditions: carrier gas (helium) pressure in the injector, 191 kPa; operational gas pressure in the column at 1 mL/min, carrier gas flow linear velocity in the column, 18 cm/s; sample volume, 1 ΐL; flow split ratio, 1:1; evaporator temperature, 260 °C. The oven temperature program was as follows: from 130 to 170 °C at 6.5 °C/min, to 215 °C at 2.75 °C/min (25 min at this temperature), to 240 °C at 40 °C/min, and 50 min at 240 °C, operational temperature of the mass selective detector, 240 °C, energy of the ionization, 70 eV. Identification of FA was done according to the retention times of standards (Sigma, St. Louis, MS, USA) and by characteristic mass spectra. The unsaturation index (UI) of FA mixtures was calculated as follows: UI = ̕ p*<sup>i</sup>* × e*i*/100, where p*i* is the percentage and e*i*—the double bond number of *i*-th FA [38]. 
