Changes in the composition of a cold-pressed hemp seed oil during three months of storage

Several analytical parameters were evaluated to investigate changes in the composition of a cold-pressed hemp seed oil over a period of 3 months of storage. The environmental conditions applied for the conservation were 12 h of light and 12 of darkness at room temperature, to mime a grocery or supermarket shelf, and the oil was stored in amber glass bottles. The peroxide value was quite low on freshly produced oil (2.66 + 0.29 mEqO(2)/kg of oil) and decreased after 3 months (1.35 + 0.08 mEqO(2)/kg of oil), as confirmed by free radical concentration, while no other statistically significant (one-way ANOVA, Tukey's HSD test, p < 0.05) differences were observed (e.g. conjugated diene and triene systems, Oxidative Stability Index and free acidity). The fatty acid, cannabinoids and tocopherols composition did not statistically change; expect for 8-tocopherol, for which a decrease was observed. The overall results did not show a strong effect of photooxidation on the oil, despite its high degree of unsaturation.