Characterization and chemometric study of crude and refined oils from table olive by-products

Table olive processing produces defective fruits and the conditioning operations give rise to solid by-products which are processed to obtain oil. In this study, the most relevant characteristics of crude oils extracted from table olive by-products were high average acidity values (4.5%, green olives; 8.1%, ripe olives), ECN42 values of 0.34 (green olives) and 0.10 (ripe olives), while 2-mono-palmitin averaged 0.92%. The overall content of sterols was 2257 mg/kg (green olives) and 1746 mg/kg (ripe olives), while the concentration of cholesterol was 36 mg/kg (green olives) and 19 mg/kg (ripe olives). The effect of refining was mainly reflected by a decrease in acidity and sterols. Although most characteristics were in agreement with the established regulation for olive oil, the overall trans fatty acid content, the low apparent beta-sitosterol content, and the relatively high cholesterol content prevented their inclusion into classes of crude or refined lampante or pomace olive oils, not even into the vegetable oil category. Therefore, the oils analyzed should be considered for non-edible purposes. The physicochemical characteristics used for chemometric discrimination permitted discrimination among types of oils (crude, 100%; physically refined, 90%; chemically refined, 100%), elaboration styles (green and ripe olives, 100%) and cultivars (Gordal, Manzanilla, Hojiblanca and Cacerena 100%), with the sterol composition being the most useful parameter for discrimination.