Supercritical CO2 impregnation - selection of suitable polymeric carrier for hemp seed oil

Abstract

Supercritical CO2 impregnation (SCI) process allows incorporation of bioactive components into solid carriers in an environmentally friendly manner. In recent years, SCI was highlighted as a promising method for preparation of added value materials that can protect bioactive components from environment (sun light, air, moisture etc.), stabilise them, and increase their shelf life. SCI process is also suitable for preparation of material with controlled release of bioactive component. Taking into account the above-mentioned, SCI process was employed in this study for incorporation of hemp seed oil (HSO) into biocompatible polymers (starch xerogel, starch aerogel, α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin). Given that efficiency of SCI depends on process conditions and affinity of bioactive component towards scCO2 and polymer, it is necessary to optimise process for every individual system. Proposed SCI process was performed at pressure of 30 MPa and temperature of 40 °C during 5 h and 18 h. FTIR analysis confirmed that scCO2 did not have effect on polymer composition nor it remained in polymer after process. Additionally, FTIR and UV-Vis analysis showed that HSO is present in all tested polymers after SCI process. It was shown that impregnation of HSO is highly dependent on selection of polymeric carrier (its chemical composition and morphology) and operating time employed, resulting in loadings from 0.5% to 40%. Chemical analysis showed that HSO is rich in unsaturated fatty acids especially linoleic acid (54-60%) and α-linolenic acid (17-20%). These essential fatty acids have well-established health benefits including protection against cardiovascular, neurodegenerative and inflammatory diseases. Proposed SCI process gave guidelines for development of added-value materials that are solvent free and can be used as phytopharmaceuticals.