Fig Seeds as a Novel Oil Source: Investigating Lipochemodiversity Through Fatty Acids Profiling and FTIR Spectral Fingerprints

Abstract

Fig seeds (Ficus carica L.), a previously overlooked component of the fig fruit, have recently garnered attention as a valuable source of atypical vegetable oil and food-based ingredient. This study evaluated the oil content, fatty acid composition, and molecular FTIR-based signatures of 21 Ficus carica L. genotypes growing in an ex-situ collection. Gas chromatography analysis revealed high levels of linolenic acid (18.11 ± 0.255% to 42.276 ± 0.173%), followed by linoleic acid (27.75 ± 0.019% to 36.68 ± 0.046%). Palmitic acid (6.671 ± 0.006% to 8.908 ± 0.005%) and stearic acid (2.562 ± 0.009% to 4.160 ± 0.011) were the predominant saturated fatty acids (TSFA). The calculated oleic desaturation ratio (ODR), linoleic desaturation ratio (LDR), and ω6/ω3 ratio ranged from 0.466 ± 0.0284 to 0.710 ± 0.002, 0.330 ± 0.0998 to 0.595 ± 0.08, and 0.680 ± 0.283 to 2.025 ± 0.002, respectively. The desaturation efficiency from oleic to linoleic acid (ODR) was consistently lower than the desaturation from linoleic to linolenic acids (LDR) across all cultivars. 'Aicha Moussa' and 'Amtala Arch' exhibited the highest ODR and LDR (0.710 ± 0.002 and 0.595 ± 0.0779, respectively), potentially explaining the high C18:3 (linolenic acid) content in these cultivars. Notably, 'Amtala Arch' had an average linolenic acid content of 42.762 ± 0.173%. These findings highlight the significant lipochemodiversity within fig seeds, requiring further investigation into the potential for valorizing fig processing byproducts and creating new investment opportunities. FTIR-ATR spectroscopy coupled with chemometrics proved effective in characterizing molecular fingerprints, enabling both the rapid assessment of fig seed lipochemodiversity and enhanced sample authentication and classification.

Keywords: Ficus carica L.; fatty acid composition; fig seed oil; genotypic variation; lipochemodiversity; oil fingerprints.

Figure 1

Typical GC chromatogram of the fatty acids of fig seed oil. Example of variety ‘Hayoul ’ (C14:0: myristic acid; C15:0: pentadecylic acid; C16:0: palmitic acid; C16:1: palmitoleic acid; C17:0: margaric acid; C17:1: heptadecenoic acid; C18:0: stearic acid; C18:1: oleic acid; C18:2: linoleic acid; C18:3: alpha-linolenic acid; C20:0: arachidic acid; C20:1: eicosenoic acid; C22:0: behenic acid.

Figure 2

(a) FTIR-ATR spectroscopy data of investigated fig seeds samples in the wavenumber range from 4000 to 450 cm⁻¹. (b) Boxplot illustrating the total integrated area of the entire FTIR-ATR spectrum for each fig seed cultivar to show the differences in vibration intensities across the samples. (c) FTIR-ATR spectrum of the local clone ‘El Qoti Lezreq’ fig seeds highlighting key peaks in the wavenumber range of 4000 to 450 cm⁻¹.

Figure 3

3D PCA plot of FTIR spectral fingerprints of studied fig seeds visualizing biochemical variation in fig seeds.

Figure 4

Lipochemical diversity of fig seed cultivars: a 3D PCA visualization based on fatty acid profiles.