Fibre hemp inflorescences: From crop-residues to essential oil production

The volatile compn. of ten fiber hemp (Cannabis sativa L.) varieties was investigated during two successive growing seasons under temperate climatic conditions in Central Italy. The freshly plant inflorescences were hydrodistd. and the essential oils (EOs) were characterized by GC-MS. In addn., the compn. of the aroma emitted spontaneously from the freshly plant inflorescences were analyzed by SPME-GC-MS. The EO yields of eight dioecious (Carmagnola, C.S., Red Petiole, Pop 1, Pop 2, Pop 3, Pop 4, Pop 5) and two monoecious (Codimono and Felina 34) cultivars ranged from 0.11 to 0.25% (wt./wt.) and showed a significant prodn. of α-pinene (3-20%), β-pinene (1-8%), E-ocimene (1-10%), myrcene (8-45%) and terpinolene (0.12-22%). The monoterpene compn. was useful to distinguish the monoecious cultivars from the dioecious ones. β-Caryophyllene (7-28%), α-humulene (3-12%), and caryophyllene oxide (2-6%) were the main sesquiterpenes. Tetrahydrocannabinol (THC) was present in traces in the EOs of only two dioecious cultivars cultivated in 2005. Cannabinol (CBN) was not detected in the essential oils, while the no-hallucinogenous cannabidiol (CBD) was found as typical volatile constituent in several analyzed cultivars. These findings were also confirmed by the headspace GC-MS anal. carried out on the same samples. The analyzed EOs obtained from fiber hemp varieties cultivated in Central Italy were characterized by an interesting and specific terpene compn. with a legal and safe cannabinoid content. They were obtained from freshly plant inflorescences, which usually represent a waste material from C. sativa L. fiber varieties. The present study strengths the hypothesis to grow hemp as a multi-use crop through a complete utilization of the plant material using inflorescences to produce essential oils as natural flavor and fragrance additives