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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.

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β-Glucans were isolated from six Greek barley cultivars (Persefoni, Kos, Thessaloniki, Athinaida, Dimitra and Triptolemos) by water extraction at 47 • C, enzymatic removal of starch and protein and subsequent precipitation of the water-soluble β-glucans with 37% (w/v) ammonium sulfate saturation. The purity of barley β-glucans was high (>93% dry basis) with some small contamination by protein (<3.84%). The molecular size of the β-glucan isolates was determined by high-performance size-exclusion chromatography (HPSEC); the weight-average molecular weights and the intrinsic viscosities ranged between 0.45 × 10 6 and 1.32 × 10 6 and 2.77 and 4.11 dl g −1 , respectively. Structural features of barley β-glucans were revealed by 13 C NMR spectroscopy and high-performance anion-exchange chromatography (HPAEC) of the oligomers released by the hydrolytic action of lichenase. Lichenase degradation showed that β-glucans from all barley cultivars consisted of blocks of cellotriosyl and cellotetraosyl units, accounting for 90.6-92.3% of the total oligomers released, with a molar proportion of these units between 2.31 and 2.77. Rheological measurements of aqueous solutions/dispersions of β-glucans showed the behaviour of non-interacting polysaccharides and a transition from the typical viscoelastic response to gel-like properties after a time period that depended on the molecular size of the polysaccharide. The lowest molecular size β-glucans from the Triptolemos cultivar showed shorter gelation times than their higher molecular weight counterparts. The effect of sugar incorporation (glucose, fructose, sucrose, xylose and ribose), at a concentration of 30% (w/v), to the β-glucans gels (6% w/v) on compression parameters seemed to be related to the type of sugar used; the pentose sugars substantially reduced gel firming.

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An analytical method based on an optimized solid-phase extraction procedure and followed by high-performance liquid chromatography (HPLC) separation with diode array detection was developed and validated for the simultaneous determination of phenolic acids (gallic, protocatechuic, 4-hydroxy-benzoic, vanillic, caffeic, syringic, p-coumaric, ferulic, sinapic, and cinnamic acids), flavanols (catechin and epicatechin), flavonols (myricetin, quercetin, kaempferol, quercetin-3-O-glucoside, hyperoside, and rutin), flavones (luteolin and apigenin) and flavanones (naringenin and hesperidin) in rice flour (Oryza sativa L.). Chromatographic separation was carried out on a PerfectSil Target ODS-3 (250 mm × 4.6 mm, 3 μm) column at temperature 25°C using a mobile phase, consisting of 0.5% (v/v) acetic acid in water, methanol, and acetonitrile at a flow rate 1 mL min(-1) , under gradient elution conditions. Application of optimum extraction conditions, elaborated on both Lichrolut C(18) and Oasis HLB cartridges, have led to extraction of phenolic acids and flavonoids from rice flour with mean recoveries 84.3-113.0%. The developed method was validated in terms of linearity, accuracy, precision, stability, and sensitivity. Repeatability (n = 5) and inter-day precision (n = 4) revealed relative standard deviation (RSD) <13%. The optimized method was successfully applied to the analysis of phenolic acids and flavonoids in pigmented (red and black rice) and non-pigmented rice (brown rice) samples.

The increasing interest in antioxidant properties of cereal and cereal-based products has prompted the development of a simple and reliable HPLC method for the simultaneous determination of important phytochemicals like tocopherols (T), tocotrienols (T3) and carotenoids. Separation was carried out on a Nucleosil 100 C(18) column, 5 μm (250 mm × 4.6 mm) thermostated at 25 °C, using a linear gradient elution system starting with methanol and ending with a mixture of methanol-isopropanol-acetonitrile. All separated compounds including the internal standard (α-tocopherol acetate) were eluted within 16 min and detected by dual detection: fluorescence for tocopherols and tocotrienols at 290 nm excitation and 320 nm emission and UV-vis photodiode array detection for lutein and β-carotene at 450 nm. Detection limits ranged from 0.2 μg/g (β-carotene) to 1.60 μg/g (α-tocopherol). The intra- and inter-assay coefficients of variation were calculated by using cereals with different levels of lipophilic antioxidants. The extraction method involved sample saponification and clean-up by solid-phase extraction (SPE). The extraction recoveries obtained using OASIS HLB SPE cartridges and dichloromethane as eluent were in the range of 90.2-110.1%, with RSD lower than 10%. The method was successfully applied to cereals: durum wheat, bread wheat, rice, barley, oat, rye, corn and triticale.