Characterization of oil from roasted hemp seeds using the PDSC and FTIR techniques

Abstract

The purpose of the present work was to characterize oil extracted from roasted hemp seeds using the PDSC and FTIR techniques. Roasting was conducted in a laboratory convective dryer. DSC method was used for the determination of the oxidative stability of oil extracted from hemp seeds. Pressure differential scanning calorimetry experiments were carried out using a DSC Q20, TA Instruments, coupled with a high-pressure cell. The isothermal temperature (393 K) was used for the data collection. The oxidative induction time was obtained from the PDSC curves. Infrared spectra were registered for every sample in the classic range of 4000–400 cm−1 with 1 cm−1 resolution, using System 2000 PerkinElmer instrument. The Grams AI 8.0 and TQ Analyst 8 software were used for spectral data processing. The samples of oil were also characterized by standard quality parameters: fatty acids composition (with use of GC technique), free fatty acids content by titration with 0.1 M potassium hydroxide and peroxide value determined by iodometric titration technique. Samples of oil extracted from hemp seeds after roasting in higher temperatures were characterized by lower induction time than oil from hemp seeds roasted in lower temperature. The results confirm that the induction time obtained from PDSC measurements can be used as parameters for the assessment of the resistance of oils from roasted hemp seeds to their thermal–oxidative decomposition.