Oil concentration and composition of olives during fruit maturation in south-western New South Wales

Abstract

This paper reports on an observational study of the oil and moisture content, and fatty acid profile, of olives (Olea europaea) for 15 tree groupings with groups consisting of trees with similar DNA patterns. Observations were taken at 2 sites (Wagga Wagga and Yanco) in south-western New South Wales, over 2 seasons. These sites represent the largest gene pool of developed olive trees in Australia. Differences in oil and moisture content were identified at both the Wagga Wagga and Yanco sites. At the former site, group 12 (˜cv. Tarascoa) had the highest oil content at full colour development in both 1998 and 1999 (50.1 and 45.5% dry weight, respectively) while at Yanco, group 15 (˜cv. Verdale) had the highest oil content in both years with 51.6 and 45.3%, respectively. The fatty acid profile was shown to be highly dependent upon tree group (i.e. cultivar), and with further study may be used as a method for discriminating among cultivars. The pattern of development of oil, moisture and fatty acids (palmitic, palmitoleic, stearic, oleic, linoleic and linolenic acids) is also detailed for 4 trees in the Wagga Wagga grove over the ripening season in 1998 and 1999. For these trees, oil content (dry weight basis) increased rapidly in the first 15 weeks (January–April) while moisture declined except for a small increase at around 10 weeks (mid-March). Fatty acid development showed similar trends between the trees over the length of the study.