FT-Raman and FT-IR studies of the gluten structure as a result of model dough supplementation with chosen oil pomaces

Abstract

The pomaces obtained after cold pressing oil production from oil seeds can be regarded as a source of many valuable nutrients such as unsaturated fatty acids, dietary fibre and antioxidants. The aim of the research was to determine the effect of five oil pomaces from black seed, hemp, pumpkin, milk thistle and primrose on the structure of gluten proteins. The model dough was supplemented with 3%, 6%, and 9% of the pomaces. Structural changes in gluten proteins were studied using Fourier transform Raman spectroscopy (FT-Raman) and Fourier transform infrared spectroscopy (FT-IR). Additionally, chemical composition of the pomaces was determined. Changes observed in the gluten structure resulting from the model dough supplementation with oil pomaces allow the pomace to be divided into two groups depending on the type and amount of fatty acids present in the pomaces. If the pomace contains a low number of fatty acids (black seed and pumpkin), pseudo-β-sheets are formed from β-turns and antiparallel-β-sheets in the gluten network. If the pomace contains a high number of fatty acids, non-aggregated β-structures are observed. Although the pomaces contain considerable amount of dietary fibre and polyphenols, comparison of the observed structural changes in gluten network with pomaces’ chemical composition indicates that the changes are connected with presence of fatty acids.