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Guillaume C.,Modern Olives Laboratory Services | Ravetti L.,Modern Olives Laboratory Services | Ray D.L.,Victoria University of Melbourne | Johnson J.,Victoria University of Melbourne
JAOCS, Journal of the American Oil Chemists' Society | Year: 2012

Sterols are important lipids related to the quality of olive oil and broadly used for checking its genuineness. Recent analyses have identified that some Australian olive oils would not meet international standards for total content of sterols or for certain individual components. Several research works indicate that there are some significant correlations between cultural and processing practices and sterols content and composition. In this work the horticultural and processing practices that may have an impact on the sterol content and profile of the most important Australian varieties were analysed. The information generated with this study aims to solve a legislation problem as well as maximising the nutritional and health benefits of Australian olive oils. The evaluation was undertaken using three different varieties and the processing practices evaluated were: irrigation, fruit size, maturity, malaxing time, malaxing temperature and delays between harvest and process. The total content of sterols and their composition in olive oil is strongly influenced by genetic factors and year. Processing practices particularly affect triterpene dialcohols and stigmasterol while horticultural practices and fruit characteristics tend to affect more significantly other sterols such as β-sitosterol, sitostanol, Δ5-avenasterol and Δ7-avenasterol. © 2011 AOCS.

Guillaume C.,Modern Olives Laboratory Services | Ravetti L.,Modern Olives Laboratory Services | Gwyn S.,Modern Olives Laboratory Services
JAOCS, Journal of the American Oil Chemists' Society | Year: 2010

Frost is one of the most important weather related hazards for the Australian olive industry and it has caused significant economic losses during the last decade. Its impact on oil quality was significant in 2006 with more than 20% of Australian oil of that year being affected to some degree. Early frosts will normally affect the fruit leading to significant changes in the chemical and organoleptic characteristics of the oils. The aim of this work was to study the effect of freeze damage on the phenolic composition and quality parameters of oils from three different varieties: Frantoio, Barnea and Picual. Quality chemical parameters showed significant differences in oils produced from fruit that was frozen for 2 and 4 weeks. Those chemical parameters were not significantly different in the oil produced from fruit immediately after being frosted. Nonetheless, the sensorial profile and the polyphenols showed significant changes even with oils produced within a short time after the freezing event. Those changes became more evident with the oils produced at increasing time from the moment of fruit freezing. © 2009 AOCS.

Guillaume C.,Modern Olives Laboratory Services | Gertz Ch.,Modern Olives Laboratory Services | Ravetti L.,Modern Olives Laboratory Services
Rivista Italiana delle Sostanze Grasse | Year: 2014

The effect of storage conditions (light, temperature, container types) and time on the quality of natural olive oil from different varieties and Australian regions were studied. The changing quality of the oils was monitored through several physico-chemical methods (free fatty acids, peroxide value, UV-spectrometry (K232, K270 and ΔK), induction time, total polyphenol content, bitterness, pyropheophytin a and 1,2-di-acyl-glycerol content) and sensory analysis over 24 months. Pyropheophytins a and 1,2-di-acyl-glycerols criteria showed a very good performance as indicators of overall olive oil quality and freshness as well as highlighting any problems during the storage of the product. Pyropheophytin a has an average increment of 7% per year and the 1,2-di-acyl-glycerols decreases at an average of 23% per year at normal storage conditions over time.

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