Variation in oil quality and fatty acid composition in Australian olive oil

Abstract

There is little information on the fatty acid composition or other quality aspects of Australian olive oil. In future years, it is predicted that domestic supply will outstrip demand. The industry is therefore focussed on export quality oil that meets international standards. Australia has a very variable environment that has been shown to contribute to a wide range in oil quality, both chemically and organoleptically. This paper summarises the results of the chemical analyses of 822 Australian olive oils carried out at the Wagga Wagga Agricultural Institute over 2002 and 2003. The analyses are compared with IOOC standards for extra virgin olive oil and show that Australia olive oils are generally within these standards. Peroxide values were between 1.9 and 27.2 meq/kg oil with only 10 exceeding 20 meq/kg. Free fatty acids were between 0.05 and 2.16 although they were generally less than the accepted limit of 0.8% with only 28 exceeding that level. Polyphenol content (38–1352 g/kg) and induction time (1.4–23.6 h) showed wide variation although these have no IOOC recommended standard. The fatty acid profiles also showed a considerable range with palmitic acid (saturated) levels from 7.8 to 18.9% and oleic acid (monounsaturated) from 58.5 to 83.2%. Linoleic acid ranged from 2.8 to 21.1%. Of particular concern was the range for linolenic acid from 0.42 to 1.91%. For this component, 29 oils exceeded the maximum linolenic acid level of ≤1.0% recommended by the IOOC. This data provides evidence of the variation in oil quality and fatty acid profiles resulting from Australia’s diverse environments and cultivars.