Determination of tocopherol and tocotrienol content of Greek barley varieties under conventional and organic cultivation techniques using validated reverse phase high‐performance liquid chromatography method
2012
Tsochatzis, Emmanouil D | Bladenopoulos, Konstantinos | Papageorgiou, Maria
BACKGROUND: Tocotrienols and tocopherols (tocols) are important phytochemical compounds with antioxidant activity and potential benefits for human health. Among cereals, barley is a good source of tocols. In the present study the effect of two cultivation methods, organic and conventional, on the tocol content in 12 Greek barley varieties was investigated. A validated reverse phase high‐performance liquid chromatography method (RP‐HPLC) with fluorescence detection (excitation at 292 nm, emission at 335 nm) was applied along with direct solvent extraction with acetonitrile at a 1:30 (w/v) sample/solvent ratio for tocol quantification. RESULTS: The results showed statistically significant differences (P < 0.05) between the two cultivation methods (except for δ‐tocopherol) as well as among varieties. In the case of organic cultivation the four homologues of tocotrienol (α‐, β + γ‐ and δ‐) increased, by 3.05–37.14% for α‐tocotrienol, 15.51–41.09% for (β + γ)‐tocotrienol and 30.45–196.61% for δ‐tocotrienol, while those of tocopherol (α‐ and β + γ‐ but not δ‐) decreased, by 5.90–36.34% for α‐tocopherol and 2.84–46.49% for (β + γ)‐tocopherol. A simple correlation analysis between tocols revealed a good correlation between (β + γ)‐tocotrienol and δ‐tocotrienol. Although there was a significant decrease in the important α‐tocopherol in the varieties studied under organic cultivation, there was an overall increase in tocotrienol content. CONCLUSION: The cultivation method (organic or conventional) had an important effect on tocotrienol and tocopherol concentrations in barley. An overall increase in total tocol content and a clear increment in the tocotrienol/tocopherol ratio were observed.
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