3.2 Fatty acid profile
A total of 17 and 15 fatty acids in Futura 75 and inCarmagnola , respectively, were identified and quantified by fast
GC-FID analysis, within a run time less than 7 minutes. As showed in
Table 2, the predominant fatty acid in all samples was linoleic acid
(C18:2, ω -6), ranging from about 49 to 54%. Oleic acid (C18:1cis9 ) was the second major fatty acid detected
(~15-16%), followed by α-linolenic acid (C18:3,ω -3, ~ 12-15%), palmitic acid (C16:0,
~ 7-9 %), stearic acid (C18:0, ~ 2-3%)
and γ-linolenic acid (C18:3, ω -6, ~2-3%).
In Futura 75 , the saturated fatty acids (SFA) were present in
significantly (p < 0.05) greater amount at the first
harvesting time (16.7%), whereas mono-unsaturated fatty acids (MUFA)
did not showed significant differences among the three different harvest
stages (18.7%, 18.3% and 18.1% for F1, F2 and F3, respectively).
Polyunsaturated fatty acids (PUFA), on the other hand, increased
significantly (p < 0.05) their concentration with hemp
maturation, accounting for 64.6%, 69.6% and 69.6% for F1, F2 and F3,
respectively. These trends reflect those of the main fatty acid: in
fact, PUFA was the most abundant class because of linoleic acid
concentration. In Carmagnola , SFA had a significantly higher
(p < 0.05) concentration at first harvest stage
(12.2%), than the other two (11.8% and 11.6% in C2 and C3,
respectively); while MUFA did not show significant differences between
first and third harvest stages (18.2% and 18.0%, respectively), with a
slightly decrease in the middle stage (16.7%). PUFA, on the contrary,
showed a significant increase (p < 0.05) at the second
harvest stage (71.6%), between first and third harvestings (69.7% and
70.5%). Comparing our results with literature, SFA content is generally
higher than data already reported for hemp native from Italy (7%, Da
Porto et al., 2012) and from other countries like Croatia (9-11%,
Petrović et al., 2015), Spain (11%, Montserrat-de la Paz et al., 2014)
and Turkey (9-10%, Kiralan, Gül & Metin Kara, 2010); this because of
palmitic and stearic acid content that is higher than reported
literature. Only in a study conducted by Devi & Khanam (2019) is
reported a similar concentration of palmitic acid compared to our
results, 10% referred to hemp cultivated in India. MUFA content was
higher in our study than literature; 12-16% (Kiralan et al., 2010),
11% (Da Porto et al., 2012), 13% (Montserrat-de la Paz et al., 2014)
and 10-14% (Petrović et al., 2015). This because of oleic acid, that
represent almost the entire MUFA content. On the contrary, PUFA
determined in this study was lower than the already cited literature; in
fact, Kiralan et al. (2010) showed a 73-78%; Da Porto et al. (2012) a
80-81%, Montserrat-de la Paz et al. (2014) a 75% and Petrović et al.
(2015) a 74-80%. For this reason, the ratio between unsaturated and
saturated fatty acids reported in our study, 3-5 in Futura 75 and
5-6 in Carmagnola is slightly lower than that reported in
literature (6,7 showed by Montserrat-de la Paz et al., 2014). In
general, this characteristic high ratio between unsaturated and
saturated fatty acids can reduce serum cholesterol and atherosclerosis;
and prevent heart diseases (Reena & Lokesh, 2007). On the other hand,
because of its high unsaturation level and susceptibility to oxidation,
hemp seeds oil has a short shelf life (Kiralan et al., 2010) and it is
not suitable for hot uses (Da Porto et al., 2012).
As regard to the ratio between the two essential polyunsaturated fatty
acids, linoleic and α-linolenic acid, both varieties, Futura 75and Carmagnola , showed the highest value at the first harvest,
4.05 and 3.90, respectively (Table 2). This even though linoleic and
α-linolenic acids did not have the same trend in the two different
varieties. In Futura 75 linoleic acid showed a significant
(p < 0.05) increase from the beginning to the end of
maturation (49.2%, 52.3% and 52.5% for F1, F2 and F3); inCarmagnola , instead, its concentration increased significantly
(p < 0.05) from first (53.7%) to second harvest
(54.7%) and then decreased again at the third harvest stage (53.9%).
α-linolenic acid, instead, in Futura 75 increased significantly
(p < 0.05) between first (12.1%) and second harvest
(14.3%), before decreased again at third harvest stage (13.9%); inCarmagnola its concentration increased significantly during all
the maturation; 13.8%, 14.6% and 14.9% for C1, C2 and C3,
respectively. The high quantity of α-linolenic acid improves hemp oil
quality for its positive nutritional implications and beneficial effects
against coronary disease and cancer (Arshad, Al-Leswas, Stephenson,
Metcalfe & Dennison, 2011; Fretts et al., 2013). In general, our
results about these two fatty acids are slightly lower than results in
literature. In fact linoleic acid content is reported in a range between
48 and 59% and α-linolenic acid in a range between 16 and 26%
(Montserrat-de la Paz et al., 2014; Orsanova, Misurcova, Ambrozova,
Vicha & Mlcek, 2015; Petrović et al., 2015; Mikulcová, Kašpárková,
Humpolíček & Buňková, 2017; Devi & Khanam, 2019; Siudem et al., 2019).