Influence of thermal processing on cannabinoids contents and profiles in hemp seed oil

German. The thermal decarboxylation of tetrahydrocannabinolic acid (THCA) to Δ9- tetrahydrocannabinol (Δ9-THC), the psychoactive component of Cannabis sativa L., could be relevant for food safety. Little is known about the extent to which this and other reactions occur during thermal food processing such as frying. Maximum levels for Δ9-THC equivalents (Δ9-THC+0.877*THC-acid) of 7.5 mg/kg have been regulated for hemp seed oils in the EU. Hemp seeds themselves are practically free of cannabinoids, but can be contaminated with cannabinoids during harvest through contact with other parts of the plant. Subsequent pressing of the seeds releases the cannabinoids into the oil. In this study, 16 cannabinoids were quantified in commercial hemp seed oils (n = 30) using an HPLC-MS/MS method. The Δ9-THC equivalents ranged from 0.3 to 7.7 mg/kg. Three samples exceeded the EU maximum levels for Δ9-THC equivalents of 7.5 mg/kg. Specific product features declared on the packaging of hemp seed oils (e.g., use of roasted seeds) can be recognised by the cannabinoid profiles (e.g., high ratio of neutral to acidic cannabinoids). Two oils showed deviating profiles with high levels of THCA/Δ9-THC, indicating a possible origin, at least in part, from medicinal hemp. In another part of this study, hemp seed oils were processed at 130-200 °C for 10-60 min. At maximum temperature stress (200 °C/60 min) a 38% decrease in total cannabinoid content and an almost complete decarboxylation of cannabinoid acids (-99%) was observed. Besides decarboxylation, volatilisation and other transformation reactions could be the cause. In terms of transformation, the oxidation of Δ9-THC to cannabinol (CBN) was observed. The Δ9-THC equivalents decreased by 28% under maximum temperature stress. However, the decarboxylation of THCA led to a 22% increase in Δ9-THC itself.