Machines for olive paste preparation producing quality virgin olive oil

Abstract

Polyphenolic substances enhance the resistance to oxidation of virgin olive oils, but an excess of polyphenols determines a marked bitter, somewhat tannic taste of the oil, similar to the taste of unripe olives. Tests have been carried out on drupes of different cultivars in industrial productions to evaluate the effect of the machines used to prepare olive pastes on the contents of polyphenols in the oils. Notably greater amounts of polyphenols were found in the oils extracted from hammer‐crushed pastes than in the oils extracted from milled pastes. The kneading process which follows, especially if it is long, often reduces the amounts of total polyphenols. Therefore, in order to obtain the best organoleptic and chemical quality in extra virgin olive oils, two systems are suggested for the processing procedures. For olives of certain cultivars (Coratina) and for not‐blackened or slightly blackened drupes yielding oils with a very high content of total polyphenols, it is most expedient to use the stone‐mill together with a kneader system. But it is more suitable to utilize the hammercrusher together with a kneader system in processing olives (such as the Ogiiarola Salentina or Leccino cultivars) yielding normally “sweet” oils with a low content of total polyphenols.

Influence of the type of olive‐crusher used on the quality of extra virgin olive oils

“…For the trials Coratina olives were used, because it is one of the more common cultivars in the Apulia region. Oil from Coratina olives is characterised by a high amount of phenolic compounds [1,2] that may determine lesser oxidation of the oil due to temperature rises in the paste during crushing. In fact, more evident variations in the oxidation level are to be expected when utilising oils containing smaller amounts of phenolic compounds.…”

“…Previous papers of the present authors [1,2,6,7] have emphasised the possibility of using a stone mill or a hammer-crusher for olive paste preparation depending on the type of cultivar involved. This is done to obtain extra virgin olive oils with desirable organoleptic properties without jeopardising their shelf life.…”

“…The possibility of resorting to enzymatic treatments to improve the yields and to upgrade the oil quality has also been explored. Numerous experimental studies have also focused on defining the quality of the oils obtained using the different technologies proposed [1][2][3][4][5].…”

Hydrophilic antioxidants of virgin olive oil. Part 2: Biosynthesis and biotransformation of phenolic compounds in virgin olive oil as affected by agronomic and processing factors

“…In fact, while genetic, agronomic and environmental factors determine the chemical and biochemical composition of olive fruit [36][37][38][39] the technological factors, mainly milling and malaxation, are the most critical steps during olive processing and oil extraction where the most important changes in VOO phenolic composition occur [40][41][42].…”

Olive (Olea Europaea L.): Southern-Italian Biodiversity Assessment and Traceability of Processed Products by Means of Molecular Markers

“…To this purpose, only certified material from the Experimental Station "P. and ripe drupes following the protocol proposed by Sharp et al (1988) with some modifications. Monovarietal olive oil was obtained by mechanical extraction with the method proposed by Catalano & Caponio (1996) and, after centrifugation of 250 ml oil, the cell residue sediment was recovered and used for the DNA extraction with the same protocol of leaves and drupes. DNA extracted from leaves and drupes was rich in PCR interfering substances such as phenolic compounds and lipids, suggesting a further purification achieved by chromatography on a commercial device.…”