3.1 Oil and moisture content
Table 1 shows oil content of Futura 75 and Carmagnola at three different harvest stages expressed on dry basis. Futura 75showed a significantly higher (p < 0.05) oil content during the second harvest stage (29.9%) rather than the other two harvestings, 22.9% and 26.4% for the first and the third harvest, respectively. On the other hand, Carmagnola did not show any significant differences (p < 0.05) in oil content during maturation, in fact it was 24.5%, 24.8% and 24.9% at first, second and third harvest, respectively. Our results are in line, or slightly lower, with literature, Latif & Anwar (2009), Da Porto, Decorti, Tubaro (2012) and Kostić et al. (2014) that reported an oil content of 26-32%, 30% and 25-29%, respectively. The lower oil content may be attributed to cultivation techniques and climatic conditions; in addition, seeds were covered by a green skin that certainly influenced the oil content, since it covered completely the seed.
As regard moisture (Table 1), an expected reduction in percentage of moisture was recorded in both varieties with the increasing of maturation; it is well known that immature seeds contain a higher water content rather than mature seeds (Matthäus & Brühl, 2006). Futura 75 starting from a moisture value of 50% at F1, that decreased significantly (p < 0.05) at F2 (32%) reaching a final value of 20% at full maturity. Moisture content in Carmagnolahad the same trend, starting from a value of 31% at C1 and decreasing significantly (p < 0.05) at C2 (17%) and finally at C3 (10%). Moisture value reported in various studies, Oomah et al. (2002), Tang, Ten, Wang & Yang (2006) and Da Porto et al. (2012), are much lower than ours; in fact, they reported values of 7.7, 6.7 and 7.8%, respectively. This could be due to the green skin, as previously mentioned, that covered the seeds that certainly had a high impact on moisture content. Sacilik, Öztürk & Keskin (2006) conducted a study on physical properties of hemp seeds (size, density and porosity) as a function of moisture content and found out values more similar to ours (ranging from 8.6 to 20.9%).