Effect οf Genotype and Growing Year on the Nutritional, Phytochemical, and Antioxidant Properties of Industrial Hemp (Cannabis sativa L.) Seeds

Abstract

Cannabis sativa L. seeds have been an important source of protein, oil, and dietary fiber for human and animals. Currently, there is a growing interest in the commercial products of these seeds, which are recognized as a legitimate source of medicaments, cosmeceuticals, and nutraceuticals. The objective of this study was to investigate the nutritional, phytochemical composition, and antioxidant properties of seeds from seven hemp cultivars grown in Greece for three consecutive years. All the measured parameters strongly varied under the influence of growing year and genotype. In particular, protein, oil, and carbohydrates' content of hemp seeds as well as fatty acids' composition were mainly affected by genotype, whereas the growing year had a major effect on phytochemical components and antioxidant activity, which was determined by the 2,2'-azino-bis (3-ethylbenzthiazoline sulfonate) (ABTS) and ferric-reducing antioxidant power (FRAP) assays. Moreover, a predominant effect of the year was observed for phenolic profiles as determined by high-performance liquid chromatography and total carotenoids' content. This study suggests that hemp seeds could be a promising food crop as a result of their high nutritive traits and antioxidant potential. A comparison of the studied cultivars, showed that Finola seeds had the highest oil and protein contents and, thus, appeared to be the most promising cultivar for cultivation in Greece.

Keywords: antioxidant; fatty acid profile; genotype; growing year; hemp seed (Cannabis sativa L.); lignanamides; nutritional components; phytochemicals.

Figure 1

Nutritional profile showing the oil, protein, ash, and carbohydrate contents (g 100 g⁻¹ seed) of hemp seeds from the seven industrial hemp cultivars cultivated in this study and for three growing seasons (2016, 2017, and 2018). For each year, means within columns in the same color followed by the same letter (lower case, capitals, and lower case in bold for 2016, 2017, and 2018, respectively) are not significantly different (p > 0.05).

Figure 2

Total phenolic content (TPC) of hemp seeds from the seven industrial hemp cultivars cultivated in this study for three growing seasons (2016, 2017, and 2018). For each year, means within the column in the same color followed by the same letter are not significantly different (p > 0.05).

Figure 3

High performance liquid chromatography (HPLC) chromatogram of Felina hempseed phenolic extract at 280 nm. Peaks identification: 1, protocatechuic acid. 2,4-hydroxybenzoic acid. 3, vanillic acid. 4, p-coumaric acid. 5, ferulic acid. 6, N-trans-caffeoyl-tyramine. 7, cannabisin A. 8, cinnamic acid.

Figure 4

The main phenolic acid components of hemp seeds from the seven industrial hemp cultivars cultivated in this study for three growing seasons (2016, 2017, and 2018). For each year, means within the column in the same color followed by the same letter (lower case, capitals, and lower case in bold for 2016, 2017, and 2018, respectively) are not significantly different (p > 0.05) (N-trans-caffeoyl-tyramine and cannabisin A are expressed in trans-cinnamic acid equivalents).

Figure 5

Antioxidant activity of extracts of hemp seeds from the seven industrial hemp cultivars cultivated in this study and for three growing seasons (2016, 2017, and 2018) as measured by 2,2′-azino-bis (3-ethylbenzthiazoline sulfonate) (ABTS) and ferric-reducing antioxidant power (FRAP) assays. For each year, means within the column in the same color or in the same line followed by the same letter are not significantly different (p > 0.05).