Influence of olive crushing methods on the yields and oil characteristics

Abstract

In the last years, metallic crushers substituted granite stone mill with some variations in the organoleptic oil characteristics. To control the influence of the crushing method on the yield and oil quality, the olive pastes were obtained using three different ways: (i) new metallic crusher at mobile knives; (ii) granite stone mill; (iii) double olive crushing by the metallic crusher and the granite stone mill. With the aim to ascertain the useful use of a new metallic crusher (at mobile knives), experimental tests were carried out in an industrial oil mill. This oil mill is equipped by a centrifugal decanter generating two oil flows: first and second extraction (recovery) oils. The results showed that the yields obtained by different methods were satisfactory. No statistically significant differences have been observed in terms of oil yield and quality when different crushing devices were used. All first extracted oils are extra virgin with similar organoleptic characteristics, especially for the fruity intensity and for the bitter and pungent taste, as confirmed by the composition of volatile substances and the content of phenolic oil compounds. The recovery oils (second extraction oils) showed, in contrast to first extraction oils, a more intense green colour and a higher content of total phenols.Practical applications: Processing of sound olives with the right ripening grade and good quality allows to easily obtain an extra virgin olive oil, with commercial qualitative parameters according to the European Union requirements. However, different olive crushing systems affect the concentrations of some compounds responsible of aroma and taste (phenolic compounds). The use of the more violent metallic crushers facilitates obtaining oils with total phenol content higher than when using a stone mill. Here we used a particular metallic crusher (at knives) that, however, is suitable to replace the granite stone mill when a less pungent and bitter oil is required.

Olive Oil Processing: Current Knowledge, Literature Gaps, and Future Perspectives

“…The traditional extraction method shows some advantages such as high extraction yields, low moisture content in the oil, cheap equipment, and low volume of the produced wastewater due to the addition of small quantity of water during the process. Nevertheless, it also exhibits other disadvantages, such as process discontinuity, low capacity, and high manpower costs (Caponio et al, ; Preziuso et al, ; Veillet et al, ). Nowadays, the traditional extraction systems have been replaced by modern ones that include metallic crushers, malaxers, and centrifugation separation systems.…”

“…Crushing the olives is a physical process used to break the olive fruit tissues and release the oil droplets contained in the vegetable cell vacuoles. The selection of the appropriate equipment and crushing conditions strongly affects the production yield and the quality of the extracted olive oil (Amirante et al, ; Antonio et al, ; Caponio et al, , , ; Caponio and Gomes, ; Kalogianni, ; Koutsaftakis et al, ; Luaces et al, ; Nenadis et al, ; Preedy and Watson, ; Preziuso et al, ; Sánchez‐Ortiz et al, ; Servili et al, , ; Talbot, ; Veillet et al, ).…”

“…There are various types of equipment used for crushing such as the hammer mill, the cones, the rollers, the disk or toothed crusher, the mobile‐knives, and destoner (or depitter) (Di Giovacchino et al, ). Each type of crusher has different characteristics, advantages, and drawbacks that affect the quality of olive oils (Antonio et al, ; Caponio et al, , , Caponio and Gomes, ; Clodoveo et al, ; Koutsaftakis et al, ; Nenadis et al, ; Preziuso et al, ; Servili et al, ; Veillet et al, ). Table summarizes the main characteristics, the advantages, and drawbacks, as well as the quality of the oil obtained by the various types of metallic crushers.…”

Double extraction of olive oil in large oil mills of Southern Italy: Effects on extraction efficiency, oil quality, and economy of the process

“…On virgin olive oil samples, were determined: the values of the commercial qualitative characteristics, according to the European Official Method of Analysis [14]; the chlorophyll pigments [15]; the total phenols content [16], extracted according to the method reported in other paper [17], and the single phenols by HPLC [18,19]; the composition of sterols, triterpene dialcohols, aliphatic and triterpene alcohols [14], and waxes [20]; the composition of the volatile substances by the dynamic headspace GC, using 1-nonanol as internal standard [21].…”

Influence of the nocturnal harvesting of olives from Salento (Italy) on the quality of the extra virgin olive oil

“…Their formation is stimulated in plant cells after the rupture of the cell wall, and regarding the olive fruit, this starts during the milling and continues through the malaxing. The levels of these volatile compounds that remain in the olive oil are a function of the oxidoreductase activity in the fruit, the amount of water, and the time and temperature of the malaxation (Di Giovacchino et al, 2002;Morales and Aparicio, 1999;Preziuso et al, 2009Preziuso et al, , 2010. The time and temperature of the kneading are two of the main factors that influence the activity of the enzymes that lead to the synthesis of aromas: lipoxygenase and hydroperoxide lyase.…”