Dry-air pretreatments effects on physiochemical properties, stability, antioxidants, phytosterol and tocopherol profiles of hemp oil

Abstract

The study investigated effects of dry air pretreatment (DAP) at varying temperatures (160˚C, 180˚C, and 200˚C) and times (5-, 10-, 15-, and 20-min) on hemp oil (HeO) quality attributes. The total flavonoid (TfC) and phenolic (TpC) content, tocopherols, phytosterols, flavonoids, phenolic acids, oxidative stability index (OSI), colour attributes, Maillard products, fatty acid profile (FAP), physiochemical properties and radical scavenging activity (RsA) of HeO were studied. DAP had increased Maillard products, browning index, p-anisidine value, viscosity and ΔE while decreased peroxide, a* , b* and L* values of HeO. The TpC, TfC, RsA, phenolic acids (protocatechuic, 4-hydroxybenzoic, ellagic, chlorogenic, rosmarinic and trans cinnamic acids), epicatechin, total hydroxycinnamic and hydroxybenzoic acids and total flavonoids were highest in HeO upon DAP at 200 oC for 15 min. The tocopherols and phytosterols were highest upon DAP at 180 oC for 5 and 10 min, respectively. The highest HeO yield (25.85%) and OSI (6.80 h) was attained upon DAP at 180 oC and 200 oC for 10 min, respectively. In conclusion, the DAP had triggered a Maillard reaction, augmented the release of antioxidants, pigments and increased the OSI of HeO. The optimal DAP can be employed for the improvement of HeO quality attributes.