**7. Factors that affect the sensory quality of virgin olive oil**

The evaluation of exactly how various factors affect the sensory quality of the final product is essential in order to distinguish among different types of oil. The following factors all play a role in producing high quality olive oil (Angerosa, 2002; Angerosa *et al.*, 2004, Benincasa *et al.*, 2011).

*Cultivar.* The numerous varieties constitute an important element for the production of extra virgin olive oils, characterised by different organoleptic characteristics.

*Cultivation Techniques (irrigation, fertilization, treatment of plants, diseases etc).* Among the environmental factors that influence the quality of the olives and therefore the oil, both the temperature and the amount of water available have an important role, with the first affecting the acidic composition of the olives, while the latter the amount of phenolic substances.

*Maturation of the olive.* An early harvest generally gives a more bitter and spicy oil due to the high phenol content.

*Harvest and Storage of the olive.* The quality of the oil is highly conditioned by the state of integrity of the olive. Traditional manual harvesting techniques avoid damaging the fruit in comparison to mechanical methods. Storage of the olives in not very big crates, avoids an excessive mass of olives that could either become crushed or overheated, facilitating attacks from micro-organisms as well as oxidation and fermentation.

234 Olive Germplasm – The Olive Cultivation, Table Olive and Olive Oil Industry in Italy

*Heated:* prolonged heating during extraction processing.

oil gives off very unpleasant odours.

same time.

*al.*, 2011).

substances.

high phenol content.

*Flat:* oils which have lost their characteristic aroma and have neither taste nor smell.

*Fusty:* due to olives fermenting in piles while in storage waiting to be pressed.

*Muddy:* typical odour of oil that has been stored to long on its own sediment.

*Musty:* mouldy smell from olives being stored too long before pressing.

*Metallic:* oils processed or stored with extended contact to metal surfaces.

*Rancid:* old oils that have started oxidizing due to exposure to light or air.

*Wine-vinegar:* typical odour of wine or vinegar due to fermentation of olives.

**7. Factors that affect the sensory quality of virgin olive oil** 

virgin olive oils, characterised by different organoleptic characteristics.

water after pressing that they have remained in contact for too long.

*Frozen:* due to olives which have been exposed to freezing temperatures. When cooked, this

*Grubby:* smell imparted by grubs of the olive fly. The smell is both rotten and putrid at the

*Vegetable water:* oils that have absorbed the unpleasant odours and flavours of the vegetable

The evaluation of exactly how various factors affect the sensory quality of the final product is essential in order to distinguish among different types of oil. The following factors all play a role in producing high quality olive oil (Angerosa, 2002; Angerosa *et al.*, 2004, Benincasa *et* 

*Cultivar.* The numerous varieties constitute an important element for the production of extra

*Cultivation Techniques (irrigation, fertilization, treatment of plants, diseases etc).* Among the environmental factors that influence the quality of the olives and therefore the oil, both the temperature and the amount of water available have an important role, with the first affecting the acidic composition of the olives, while the latter the amount of phenolic

*Maturation of the olive.* An early harvest generally gives a more bitter and spicy oil due to the

*Harvest and Storage of the olive.* The quality of the oil is highly conditioned by the state of integrity of the olive. Traditional manual harvesting techniques avoid damaging the fruit in comparison to mechanical methods. Storage of the olives in not very big crates, avoids an excessive mass of olives that could either become crushed or *De-leafing and washing of the olive.* Before being processed, the olives must be cleaned of any superfluous material, including leaves, and branches. These are all elements that can negatively influence the quality of the oil.

*Pressing.* The olives are broken during the pressing phase with the skin and the pulp being lacerated as well as the stone crushed. The press can be a traditional "pan-mill" one, either in a discontinuous system or combined with an extraction system in order to carry out continual centrifugation. These presses can either be hammers or disks. Metal presses have a more violent pressing of the olive (above all hammered ones) as well as a greater laceration of the skin, giving a higher extraction of the phenolic composites and therefore a more bitter and spicy oil that lasts longer.

*Kneading.* Prolonged kneading and high temperatures could increase the activity of pectoltic and proteolitic enzymes, negatively modifying the chemical-physical characteristics and therefore the quality of the oil.

*Extraction.* The systems to separate the liquid from the solid can be divided into two groups:


*Centrifugation.* The oily liquid contains a certain amount of water (called "of vegetation") that is eliminated by centrifuging the product. This operation allows the suspended solid substances to also be eliminated. Water is often added in order to rid the oil of the watery impurities. However, this reduces the phenolic substances content.

*Clarification and filtration.* The oil obtained from centrifugation still contains mucilage, water and small pieces of the fruit. It is also turbid and opalescent. A clarification process is then carried out in order to eliminate these substances that can favour hydrolysis and/or oxidation. Traditional clarification methods include sedimentation, and have now been substituted by filtration. "Light" filtration systems are preferable rather than more drastic ones that can provoke a reduction in the anti-oxidants and subsequently a reduced shelf-life with the possibility of turning rancid.

*Conservation of the oil.* In order to maintain both the chemical-physical and organoleptic properties of the oil, the conservation conditions must be controlled. The main factors affecting the conservation of oil are:


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c. oxygen in the air (a series of oxidation reactions occur when the oil comes into contact with the air, modifying the chemical composition and subsequently the colour, smell and flavour). It is therefore good practice to store extra virgin olive oil in a sealed environment.
