Furan fatty acid content and homologue patterns of fresh green matrices

Furan fatty acids (furan-FAs) are valuable antioxidants which are supposed to play an important role in the protection of polyunsaturated fatty acids from getting oxidised. Scattered literature reports indicated that these fatty acids are widely present at low concentrations in various biological and food samples. Here, we determined the furan-FA composition in 35 samples including seven fresh herb matrices, as well as in spinach and grass. Samples were transesterified and furan-FAs were enriched from the fatty acid methyl ester fraction by means of silver ion chromatography followed by analysis with gas chromatography with mass spectrometry operated in selected ion monitoring mode (GC/MS-SIM). The samples featured between one (rosemary) and eight different furan-FAs (curly-leaf parsley). Six saturated and four unsaturated furan-FAs were identified with clear dominance of β,β'-dimethyl-substituted representatives. The total amount of furan-FAs ranged from 15 to 2650 μg/100 g fresh weight with dill, grass and curly-leaf parsley being the richest sources among the sample matrices. The rarely described unsaturated furan-FAs were detected in eight of the nine matrices and were predominant in flat-leaf parsley. Curly-leaf and flat-leaf parsley as well as fresh and deep-frozen spinach samples showed remarkable differences in the furan-FA pattern.