Lara, Australia
Lara, Australia

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Juliano P.,CSIRO | Bainczyk F.,CSIRO | Bainczyk F.,University of Mannheim | Swiergon P.,CSIRO | And 7 more authors.
Ultrasonics Sonochemistry | Year: 2017

High-frequency ultrasound standing waves (megasonics) have been demonstrated to enhance oil separation in the palm oil process at an industrial level. This work investigated the application of megasonics in the olive oil process on laboratory and pilot scale levels. Sound pressure level and cavitational yield distribution were characterised with hydrophones and luminol to determine associated physical and sonochemical effects inside the reactor. The effect of water addition (0%, 15%, and 30%), megasonic power levels (0%, 50%, and 100%), and malaxation time (10 min, 30 min, and 50 min) was evaluated using response surface methodology (RSM) in a 700 g batch extraction process. The RSM showed that the effect of the megasonic treatment (585 kHz) in the presence of a reflector is more prominent at longer malaxation time (50 min) and at higher water addition (30%) levels post-malaxation. Longer megasonic treatment of the malaxed paste (up to 15 min; 220 kJ/kg) increased oil extractability by up to 3.2%. When treating the malaxed paste with the same specific energy, higher oil extractability was obtained with longer treatments and low megasonic power levels in comparison to higher power levels and shorter times. Megasonic treatment of the paste before malaxation (585 kHz, 10 min, 146 kJ/kg) and no water addition provided an increase in oil extractability of up to 3.8% with respect to the non-sonicated control. A double sonication intervention, before and after malaxation, using low (40 kHz) and high (585 kHz) frequency, respectively, provided up to 2.4% increase in oil extractability. A megasonic intervention post-malaxation (400 and 600 kHz, 57–67 min, 18–21 kJ/kg) on a pilot scale using early-harvest olive fruits resulted in up to 1.7% extra oil extractability. Oil extracted under a high sonication frequency (free radical production regime) did not impact on olive oil quality parameters at reactor characterisation levels. Megasonic standing wave forces can enhance olive oil separation at various stages of the olive oil extraction process. © 2017


Guillaume C.,Boundary Bend Ltd | Ravetti L.,Boundary Bend Ltd | Canamasas P.,Boundary Bend Ltd | Johnson J.,University of Vic
Acta Horticulturae | Year: 2012

Sterols are important lipids related to the quality of the 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 would indicate that there are some significant correlations between cultural and processing practices and sterols content and composition. In this work we analysed the horticultural and processing practices that may have an impact on the sterol content and profile of the most important Australian cultivars. The information generated with this project does not only aim to solve a legislation problem but also to maximise the nutritional and health value of the Australian olive oils. The evaluation was undertaken in three different cultivars and the horticultural and 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.


Guillaume C.,Boundary Bend Ltd | Ravetti L.,Boundary Bend Ltd | Gwyn S.,Boundary Bend Ltd
Acta Horticulturae | Year: 2012

Frost is one of the most important weather related hazards for the Australian olive industry and it caused significant economic losses during the past decade. Its impact on oil quality has been 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 cultivars: 'Frantoio', 'Barnea' and 'Picual'. Quality chemical parameters showed significant differences in oils produced from fruit that was frozen for two and four weeks. Those chemical parameters were not significantly different in the oil produced from fruit immediately after being frosted. Nonetheless, 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 freeze.

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