Effects of talc addition and operating mode on the quality and oxidative stability of virgin olive oils obtained by centrifugation

Continuous centrifugation, a widely used procedure for extraction of virgin olive oil, involves crushing olives, mixing the olive paste, and centrifugation with or without water addition (''three phase'' or ''two phase'' modes, respectively). Virgin olive oils were obtained following both procedures, with and without talc addition. Acidity value, peroxide index, UV absorption at 270 and 232 nm, glyceridic polar compounds, oxidized triglycerides, diglycerides, iron, copper, tocopherols, phenolic compounds, and oxidative stability were determined and the results statistically analyzed. The talc addition gave rise to a small increase in the oil stability and a slight decrease in oxidized triglyceride levels. The oils obtained by the ''two phase'' mode showed a greater concentration of phenolic compounds than the homologous oils obtained by the ''three phase'' mode. Oils processed by the ''three phase'' mode showed a significant correlation between their stability and their phenolic concentration.