The extra virgin cold-pressed extraction of avocado oil developed in New Zealand, based on the mechanical extraction of olive oil using grinding, malaxing and centrifugation, has traditionally extracted oil from the flesh (30% lipids) with 10% of the skin tissue included in the malaxer. A step to remove the skin (9% lipids) and seed (2% lipids) is included before extraction. Using high quality, mature and ripened fruit this process produces high quality extra virgin oils. The objective of this project was to determine the effect of inclusion of all skin and seed during the extraction of cold pressed avocado oil. Early and late season harvested ‘Hass’ avocados were extracted in laboratory scale extraction equipment. Three different tissue combinations in the malaxers were investigated: flesh with 10% of the skin tissue, flesh with all skin, flesh with all skin and seed (i.e. whole fruit). The oil yield for whole fruit compared to flesh with 10% skin for early season was 65% lower and for late season fruit it was 35% lower, where oil yield was based on %w/w of wet tissue in the malaxer. The addition of skin and seed did not result in significant differences in free fatty acids and peroxide value in the oil recovered but higher UV absorbance values (K232 and K270) were obtained in the oil from whole fruit. Although fatty acid profiles were not significantly different, the whole fruit oil was found to have significantly higher concentrations of phenolics and pigments. It was concluded that inclusion of skin and seed reduces the overall oil yield/malaxer as the mass of flesh to extract oil from was less, however more fat-soluble compounds can be extracted into oil during malaxing. It should be noted that sensory analysis was not carried out and this should be examined in the future.
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