1. Introduction
Cannabis sativa L., belonged to Cannabaceae family, is an annual plant known by its long, thin flower and spiky leaves (Montserrat-de la Paz, Marín-Aguilar, García-Giménez & Fernández-Arche, 2014).Cannabis sativa subsp. sativa is characterized by a low content of THC (Δ9-tetrahydrocannabinol), it must be lower than 0.2% on dry basis to be cultivated in most European countries (Official Journal of European Union, 2008). Industrial hemp with a low THC content has no psychoactive effects (Siudem, Wawer & Paradowska, 2019). The most common food using hemp is hempseed oil (HSO); it is a rich source of nutrients and not nutrients that provide nutritional and functional support for humans (Crescente et al., 2018). HSO represents the 25-35% of hemp seed (Callaway, 2004; Montserrat-de la Paz et al., 2014; Crimaldi, Faugno, Sannino & Ardito, 2017) and it contains more than 80% of polyunsaturated fatty acids (PUFAs) (Petrović, Debeljak, Kezić & Džidara, 2015; Siudem et al., 2019) including essential fatty acids usually not contained in oils used for human diet (Petrović et al., 2015); in particular ω-6 linoleic acid (LA) and ω-3 α-linolenic acid (ALA). In addition, LA:ALA ratio is 3:1 which agrees with European Food Safety Agency recommendations (EFSA, 2009). HSO is composed of 1.5-2% unsaponifiable fraction, a source of interesting minor compounds like tocopherols, fat-soluble vitamin D and E (Siudem et al., 2019) and phytosterols (Montserrat-de la Paz et al., 2014). Therefore, HSO has a lot of beneficial effects: cancer and cardiovascular disease prevention, cholesterol level normalization, blood pressure lowering (Devi & Khanam, 2019) and rheumatoid arthritis and dermatitis treatment (Oomah, Busson, Godfrey & Drover, 2002; Chow, 2008). For all these reasons industries are attracted by HSO for drugs, cosmetics, body care products and dietary supplement production (Callaway, 2004; Kolodziejczyk, Ozimek, Kozlowska., 2012).
To the best of our knowledge, in literature are reported only two studies about the effect of maturation on yield, quality of fiber and oil of industrial hemp. Höppner & Menge-Hartmann (2007) studied the yield and the quality of fiber and oil of different hemp cultivars in Germany at two different harvest time (“intensive flowering” and “initial seed maturity”). The different harvest stages did not have effect on stem diameter, fiber content and yield; on the other hand, seed yield and seed oil content increased with maturation while the γ-linolenic acid content decreased. Burczyk, Grabowska, Strybe & Konczewicz (2009) studied the effect of sowing density and date of harvest (beginning of panicle forming, full bloom and full seed maturity) on industrial hemp yields. They observed that the maximum yields of biomass, cellulose and fiber can be obtained at 30 kg/ha sowing density at full bloom; while considering hemp for seed or panicles the highest yields were obtained at 10-20 kg/ha of density at full maturity of panicles.
The aim of this study was the characterization of lipid fraction of two different cultivar of Cannabis sativa L., Futura 75 andCarmagnola , harvested at three different harvest stages; in order to investigate the quality of hempseed oil during the maturation, which was never investigated before. To this end, fatty acids, tocopherols and sterols content were determined using fast chromatographic techniques, HPLC and GC equipped with different detectors.