Grape seed oil structural changes and phenolics dynamics as influenced by oleogelation and emulsification as processing conditions

Abstract Oleogelation (OG) and oleogel emulsification (EM) are emerging technologies for reducing saturated fat content in foods and for obtaining solid fat replacers. The impact of structuring methods on cold-pressed (CP) or refined (RE) grape seed oil was assessed by rheological, textural, microscopy and stability analysis, since the oil type might influence the techno-functionality of the systems. The FT-IR spectra were acquired to monitor the composition of the samples, including phenolics dynamics. Rheology revealed higher G’ LVR values for samples made from RE oil and solid character in the frequency range tested for all samples. The viscosity of OG developed with shellac wax and RE oil was higher than that of oleogel developed from CP, while in the case of emulsions, the results were inversed. The OG and EM samples developed from CP oil showed higher values for textural parameters. In the micrographs of oleogels, the crystals were cross-shaped, with dimensions varying between 1 and 5 μm, and OG_CP presented a more dense crystal network. Confocal laser scanning microscopy (CLSM) revealed that oleogel emulsions are oleogel in water type. The samples showed minimal destabilization upon centrifugation. The whiteness index (WI) determined for emulsions registered a higher value than that of the oleogels and oils. Several specific phenolic compounds are present in CP oil; the current article aimed to follow the impact of the processing techniques on the stability of the bioactive compounds, while assessing the differences in the performance of the developed systems as fat replacers.