alpha-tocopherol content of Greek virgin olive oils.

alpha-Tocopherol, the main tocopherol homologue found in olive oil, was determined using normal phase HPLC. Ninety Greek virgin olive oils, selected according to a designed sampling protocol from different cultivars and regions all over Greece for three successive crop years, were analyzed. For a specific olive cultivar, which is widely used for the production of olive oil in Greece, additional measurements were made to study the effect of milling conditions on alpha-tocopherol concentration. Finally, a significant number of commercial olive oil samples (25) obtained from the retail market were analyzed. High concentrations of alpha-tocopherol were observed in most of the samples selected from various regions. Values ranging between 98 and 370 mg/kg were found (>200 mg/kg in 60% of samples). Extraction conditions were not found to influence alpha-tocopherol level. alpha-Tocopherol content of retail market samples was high, ranging from 120 to 250 mg/kg of oil (>180 mg/kg in 60% of samples). Storage of samples under domestic conditions for two years showed that good handling is quite important for retaining high alpha-tocopherol levels and for increasing, thus, the storage life and nutritional value of this exquisite oil.