Characterization of Bulgarian Rosehip Oil by GC-MS, UV-VIS Spectroscopy, Colorimetry, FTIR Spectroscopy, and 3D Excitation–Emission Fluorescence Spectra

We report the study of seven commercially available rosehip oils (<i>Rosa canina</i> L.) using GC-MS, colorimetry (CIELab), UV-VIS, FTIR, and 3D EEM fluorescence spectroscopy, including using a smartphone spectrometer. GC-MS revealed two groups of oil samples with different chemical constituents: ω-6-dominant with 45-51% α-linolenic acid (samples S1, S2, and S5-S7) and ω-3-dominant with 47-49% α-linolenic, 7.3-19.1% oleic, 1.9-2.8% palmitic, 1.0-1.8% stearic, and 0.1-0.72% arachidic acid (S3, S4). In S1 PUFA content was found to be ~75% with ω-6/ω-3 ≈ 2:1. Favorable lipid indices of AI 0.0197-0.0302, TI 0.0208-0.0304, and h/H 33.0-50.6 were observed. The highest h/H (50.55) was observed in S5 and the lowest TI (0.0208) in S3. FTIR showed characteristic lines at ~3021, 2929/2853, 1749, and ~1370 cm^-1, and PCA yielded 60-80% variation and separated S1 from the rest of the samples, while the clusters grouped S5 and S6. The smartphone spectrometer also reproduced the individual differences in sample volumes ≤ 1 µL under 355-395 nm UV excitation. The non-destructive optical markers reflect the fatty acid profile and allow fast low-cost identification and quality control. An integrated control method including routine optical screening, periodic CG-MS verification, and chemometric models to trace oxidation and counterfeiting is suggested.