The inner temperature of the olives (cv. Leccino) before processing affects the volatile profile and the composition of the oil

Application of Low Temperature during the Malaxation Phase of Virgin Olive Oil Mechanical Extraction Processes of Three Different Italian Cultivars

“…Based on the results, in the mechanical extraction process of VOO, the use of low temperature during the first phases, such as the crushing and malaxation of olive paste phases, showed that the temperature had a significant role in controlling the activities of the main endogenous enzymes (LOX, PPO and POD) that regulate both the neoformation of volatile compounds and the oxidation phenomenon of the phenolic fraction [ 3 , 5 , 8 , 16 , 17 ]. For these reasons, the research design compared three different cultivars to better assess the effects of the low temperature in relation to different olive fruits characterized by different levels of enzymatic activity and different concentrations of phenolic and volatile compounds.…”

“…These results were mainly due to the optimum temperature of hydroperoxide lyase (HPL), which was detected between 15 °C and 20 °C and showed a high increase in C 5 and C 6 compounds [ 13 ]. As demonstrated by different studies, employing the thermal treatment of olives and/or crushed olive pastes with a low temperature increased the concentration of volatile compounds, improving the fruity and herbaceous sensory notes of VOO extracted from different olive cultivars [ 14 , 16 , 17 ]. However, the impact was highly differentiated, strictly related to the genetic origin of the fruits and influenced by the specific lipoxygenase activity load of the cultivar [ 8 , 9 , 10 , 11 ].…”

The Use of a Cooling Crusher to Reduce the Temperature of Olive Paste and Improve EVOO Quality of Coratina, Peranzana, and Moresca Cultivars: Impact on Phenolic and Volatile Compounds

“…The use of low temperatures can represent an alternative approach to modulate volatile compounds and preserve a higher concentration of hydrophilic phenols (Plasquy et al, 2021b;Veneziani et al, 2021). Alternative techniques to the regulation of the temperature of olives, such as the use of cold rooms to stabilize the temperature of fruits during the storage period (Guerrini et al, 2021;Morales-Sillero et al, 2017;Plasquy et al, 2021a;Taluri et al, 2019;Yousfi et al, 2012), the application of dry ice to cool the olives during the crushing phase (Veneziani et al, 2017;Zinnai et al, 2016), or the reduction of fruit temperature before processing by means of cold water (Dourou et al, 2020), were also tested to assess the impacts on EVOO quality.…”

Adjustment of Olive Fruit Temperature before Grinding for Olive Oil Extraction. Experimental Study and Pilot Plant Trials

“…Temperatures above 35 • C increase the oil yield but induce lipolytic, hydrolytic, and oxidative degradation, affecting both phenols and volatile compounds [15]. Malaxing temperatures below 14 • C negatively affect the oil extraction performance and induce compositional changes in the resulting olive oil [12][13][14][15][16]. Extending the malaxation time up to 60 min increases the oil yield but leads to a decrease in its phenolic content and drastically reduces the shelf life of the olive oil [17].…”

“…Grinding the olives raises the temperature by at least 5 • C [18]. Consequently, obtaining the ideal malaxation temperature becomes exceedingly difficult with olive fruits that arrive at the olive oil mill at a temperature above 25 • C. Cooling the olive fruit with cold air or hydro-cooling, or passing the paste through a heat exchanger, have already been suggested as potential alternatives [16,19,20]. However, cooling the fruit right after the harvest seems more logical, as it does have the additional advantages of reducing the fruit metabolism and avoiding the action of enzymatic agents involved in deterioration processes [21,22].…”