New vitamin E isomers (gamma-tocomonoenol and alpha-tocomonoenol) in seeds, roasted seeds and roasted seed oil from the Slovenian pumpkin variety ‘Slovenska golica’

Abstract

The Štajerska region in north-eastern Slovenia and the Styria region in southern Austria have a long tradition of growing pumpkins (Cucurbita pepo L.) as an oil crop. GC-MS determination of the free and esterified minor compounds in oil of roasted pumpkin seeds from the Slovenian C. pepo L. variety ‘Slovenska golica’ revealed the presence of two previously unreported compounds: alpha-tocomonoenol and gamma-tocomonoenol. Using the GC-MS data, reference samples (Crude Palm Oil) and tocopherol and tocotrienol standards it was possible to assign and quantify alpha-tocomonoenol (17.6±0.6μg/g) and gamma-tocomonoenol (118.7±1.0μg/g) compounds in roasted ‘S. golica’ seed oil using HPLC. The concentrations of alpha-tocopherol and gamma-tocopherol were 77.9±1.9μg/g and 586.0±4.6μg/g, respectively. Surprisingly the gamma-tocotrienol concentration found was only 6.9±0.2μg/g. Analysis of the seeds from which the oil was pressed showed the initial gamma-tocotrienol amount was even lower (1.6±0.1 and 2.2±0.1μg/g in the ground and roasted seeds, respectively) than in the roasted seed oil.