Model 5973n

GC–MS analyses were performed on selected crude ethanolic extracts to identify the chemical components. A gas chromatography system (Model 6890 N; Agilent Technologies, Shanghai, China), coupled with a mass selective detector (Model 5973 N; Agilent Technologies, Delaware, USA) and a GC auto-sampler (Agilent 7683 Automatic Liquid Sampler, Santa Clara, California, USA), was employed for all analyses. Briefly, 2 μL of crude extracts (10.40 mg of DC, 10.74 mg of LC) were injected into the GC column equipped with a capillary column (122–5532 DB-5 ms, length 30.0 m, diameter 250 μm, film thickness 0.25 µm). The injection temperature was set to 250 °C. Helium was used as the carrier gas at a constant flow rate of 2 ml/min. The oven temperature program was 80 °C for 6 min, followed by a 5 °C min⁻¹ oven temperature ramp to 280 °C within 70 min. The mass spectra were recorded with a 50–500 MHz scanning range using mass spectrometry. The chromatograms and mass spectra of constituents of the crude extracts were evaluated by comparing their mass spectra with those in the database (Wiley 7N.l database, Agilent Technology, New York, USA).

Cyclic fatty acid monomers were extracted from heated linseed oil as previously described (Sebedio et al., 1987). In brief, linseed oil (Maison Orphée, Quebec City, QC, Canada) was heated in sealed tubes under nitrogen in a HP chromatograph oven (HP 68900 series) at 275°C for 12 hr. After saponification and methylation, CFAM were isolated by a combination of column chromatography and urea fractionation. Confirmation of CFAM isomers was performed by gas chromatography–mass spectrometry (GC‐MS) after picolinyl esters of CFAM were synthesized as previously described (Destaillats & Angers, 2002) and determination of each isomer of the 5‐membered and 6‐membered rings CFAM was by GC (Dobson et al., 1995). GC‐MS analyses for the confirmation of CFAM isomers structures were performed using a gas chromatograph (Hewlett‐Packard, Model 5890, Series II, Palo Alto, CA, USA) coupled with a selective quadrupole mass detector (Agilent, model 5973 N, Palo Alto, CA). Later, CFAM‐methyl esters were converted to free fatty acids by saponification (ethanol 95% and KOH) overnight at room temperature. The CFAM‐free fatty acids were filtered with 2% bentonite, and peroxides were neutralized with NaS₂O₃. The extracts were kept at −20°C until incorporation in the diet.