**6.2. Negative attributes**

*Brine:* salty taste of oil made from brined olives.

*Coarse:* a tactile sensation in the mouth due to texture of oil.

*Cucumber:* off flavour from prolonged storage, particularly in tin.

*Dreggiest:* odour of warm lubricating oil and is caused by the poor or lack of the decanting process.

*Earthy:* this term is used when oil has acquired a musty humid odour because it has been pressed from unwashed, muddy olives.

*Esparto:* hemp-like smell acquired when olive paste has been spread on Esparto mats. Smells may differ according to whether the mates are green or dried.

*Hemp:* caused by the use of filtering *panels*, which are not perfectly clean, and recalls hemp.

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

*Frozen:* due to olives which have been exposed to freezing temperatures. When cooked, this oil gives off very unpleasant odours.

Sensory Analysis of Virgin Olive Oils 235

overheated, facilitating attacks from micro-organisms as well as oxidation and

*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

*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

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

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

a. mechanical pressure on the paste through a series of operations that make the process

b. by centrifugation that is continuous. The extraction process by pressure has the risk of contaminating the oil due to wear and dirtying of the filters. The continual centrifugation system guarantees greater hygiene and therefore gives oil with elevated

*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

*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

*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

impurities. However, this reduces the phenolic substances content.

fermentation.

negatively influence the quality of the oil.

and spicy oil that lasts longer.

therefore the quality of the oil.

qualitative characteristics.

with the possibility of turning rancid.

affecting the conservation of oil are:

discontinuous,

groups:

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

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

*Heated:* prolonged heating during extraction processing.

*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.

*Vegetable water:* oils that have absorbed the unpleasant odours and flavours of the vegetable water after pressing that they have remained in contact for too long.

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