Changes occurring in phenolic compounds and alpha-tocopherol of virgin olive oil during storage.
Changes occurring in the concentrations of alpha-tocopherol, total phenols, and complex phenols linked to 3,4-dihydroxyphenylethanol (fractions FII and FIV) and p-hydroxyphenylethanol (FIII) during storage of virgin olive oil under environmental conditions were studied. Under diffused light, alpha-tocopherol was decomposed by 79% in 4 months, whereas <45% of the phenols were lost during the same period. Among the phenols, FII showed the least stability, and decreased by 72% in 6 months. Total phenols, FIII, and FIV recorded reductions in the range of 57-63% in 6 months. When the oil was stored in the dark, alpha-tocopherol, total phenols, FIII, and FIV exhibited similar profiles of degradation, reducing by 39-45% in the first 6 months and 50-62% in 12 months. FII was the least stable compound in the dark and recorded a loss of 64% in 6 months and 79% in 12 months. The levels of the above antioxidants were further related to peroxide formation. Remaining levels of these compounds at PV = 20 meq/kg ranged between 50 and 73% under diffused light and between 40 and 62% in the dark.
Okogeri
Otu
O
Laboratory of Food Chemistry, Department of Chemistry, University of Ioannina, Ioannina 45110, Greece.
Tasioula-Margari
Maria
M
D000975:Antioxidants / Q000032:analysis*; D004355:Drug Stability; D005511:Food Handling; D005519:Food Preservation; D008027:Light; D000069463:Olive Oil; D010545:Peroxides / Q000032:analysis; D010636:Phenols / Q000032:analysis / Q000737:chemistry*; D010938:Plant Oils / Q000737:chemistry*; D013997:Time Factors; D024502:alpha-Tocopherol / Q000032:analysis / Q000737:chemistry*
D000975:Antioxidants; D000069463:Olive Oil; D010545:Peroxides; D010636:Phenols; D010938:Plant Oils; D024502:alpha-Tocopherol