Abstract .In the present study, the effects of olive variety (Kroneiki, Iranian Native Oleaginous and Mission), enzyme type (Pectinex Ultra SP-L and Pectinase 1.6021) and concentration (zero, low and high concentration) on the yield, total polyphenols, turbidity, colour, acidity, peroxide value and iodine value of three enzyme-treated virgin olive oil were investigated. A 3  2  3 completely randomized experimental design (CRD) with replications was carried out. The enzyme concentration had a highly significant effect (p < 0.01) on the yield, colour, turbidity and total polyphenol level of oil, but there were not significant effects (p < 0.05) on acidity, peroxide value and iodine value. Colour and phenolic compounds content in the oils showed significant differences (p < 0.05) between 13.0–62.2% and 13.9–72.6%, respectively, as compared with control. Turbidity was reduced significantly (p < 0.01) 25.9–67.4%. On the basis of our results, the yield of oil was significantly (p < 0.01) increased (from 0.9% to 2.4%) by using processing aid. Pectinex Ultra SP-L was more effective than Pectinase 1.06021. In the case of applying Ultra pectinex SP-L, the additional income due to extra recovered oil will be 18.8 times as much production overhead.

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