Thermal and spectroscopic profiles variation of cold-pressed raspberry seed oil studied by DSC, UV/VIS, and FTIR techniques

Abstract

The characteristics of six cold-pressed raspberry seed oils, investigated by melting and crystallization phase transition analysis using differential scanning calorimetry (DSC), UV–VIS and Fourier transform infrared (FTIR) spectra, as well as the fatty acid composition, was the aim of this study. Two groups of oils samples were investigated: commercial (I-group) and laboratory-pressed (L-group). UV/VIS and FTIR spectra of raspberry seed oil revealed important wavelength and wavenumber ranges to indicate qualitative differences between I- and L-group. Regardless of the scanning rates, DSC melting curves were more suitable for detecting differences in raspberry seed oils than crystallization profiles. Based on the Principal component analysis of UV–VIS, FTIR and DSC data two groups of oils were distinguished. Fatty acids by GC analysis confirmed differences between oils, since the commercial oils exhibited a lower ratio of n-3/n-6 fatty acids than L-group oils. The obtained results provide practical information on the usefulness of DSC profiles and FTIR spectra for the comprehensive characterization of cold-pressed raspberry seed oils, especially in the field of B2B industries that need rapid and non-targeted instruments to confirm the authenticity of the purchased product.