Chemical composition, thermal stability of pomegranate peel and seed powders and their application in food production

Pomegranate seed and peel powders are suitable for the production of pectin, oil, proteins and as biologically active additives for food enrichment. Knowledge of the chemical composition and thermal changes of powders allows to control the technological regimes, yield and quality of the final product. As a result of the studies, the chemical composition and thermal properties of a finely dispersed pomegranate peel and seed powder subjected to heat treatment by X-ray diffractometry, IR-, EPR spectroscopy and thermal analysis (TG/DTG/DSC) have been carried out. X-ray diffractometry showed that the crystal structures present in the original samples, when heated in air at 110 °C for 30 min. are destroyed and in all cases the samples pass into the amorphous state, a noticeable difference is found in the position and intensity of the observed bands in the spectra in the initial and heat-treated samples. IR spectroscopy data show that drying the samples at 105 °C in air for 30 min leads to a significant change in the chemical composition of the powders. EPR spectroscopy showed the presence of paramagnetism in the samples and identified organic radicals and paramagnetic centers from Fe3+ ions. The features of the change in the chemical composition during drying of samples, which are characteristic of drying processes, namely, are the result by dehydration, dehydroxylation and denaturation of protein compounds that make up this process, have been established. Temperature intervals (54.2–147.9 and 71.7–95.4 °C, 147.9–343.7 and 343.7–466 °C) associated with changes in the composition of organic compounds, contained in the powders were determined.