Olive oil Quality Criteria

Olive oil quality criteria are mentioned below in the following concise list. Some of them are described in a concise manner later on.

Concise list of olive oil quality criteria




 Cultivar, climate, soil


 Pre-harvesting treatments (Conventional olive oil, Organic farming product, Integrated Management System product)


 Harvesting and post-harvesting treatments: Harvesting (maturity stage – green olive oil etc, bruising during harvesting –Transportation – Storage of the olive fruit (storage duration and conditions) – Olive oil extraction at the olive mill (type of olive mill, hygiene conditions) – Storage of olive oil


 Marketing quality types of olive oil (Extra virgin olive oil, Virgin olive oil, Olive oil and Olive-pomace oil)


 PDO-PGI Products (Protected Designation of Origin, Protected Geographical Indication)


 Organoleptic assessment of virgin olive oil (aroma, flavour: fruity, bitter, spicy, mould, sediment, metallic, rancid)


 Olive oil alterations (Hydrolysis caused by humidity, temperature, ferments, micro-organisms, Oxidation - smell, bad flavour, caused by air, high temperature, light, metals)


 Risks for olive oil quality (olive oil unsuitable for consumption: residues of pesticides, heavy metals from the olive mill machinery, environmental pollutants etc)


 Food safety and hygiene (measures for mandatory implementation, control procedures, HACCP – Method for ensuring the production of healthy products – ISO International organization of quality standards)


 Traceability (detection for control from the point of origin of the raw material until the shelf and the plate of the consumer)


 Selection of raw materials (packaged olive oil quality, supplementary materials, packaging materials)


 Olive oil authenticity (blending with other oils such as seed oils etc)


Cultivar, climate, soil

Pre-harvesting factors affecting the quality of olive oil

Harvesting-transportation-storage-olive oil extraction & quality

Quality affects in particular the organoleptic characteristics (aroma, flavour). The koroneiki cultivar , which is dominant in Crete, is believed to provide olive oil of top quality characteristics.

Olive oil organoleptic characteristics are also affected by the climate and the soil of the cultivation area. There are more aromatic ingredients in areas with long periods of sunshine. This becomes even more important for the quality certification of olive oils of Protected Designation of Origin (PDO) and Protected Geographical Indication (PGI).

The olive oil that is produced from olive trees in dry-limestone soils has more aromatic ingredients than the one produced in moist-clay soils.

In general, insect and fungal attacks create the conditions for the alteration of the quality of olive oil. Consequently, proper pesticide control contributes in the production of quality olive oil.

To produce good quality olive oil, producers must take the following precautions during harvesting and post-harvesting:

  • The olive fruit must be in perfect maturity stage during its harvesting (yellow-violet colour). Unripe olives produce olive oil with green colour and bitter flavor (green olive oil). From an over-ripe olive fruit usually is produced an olive oil with increased acidity, less aroma, total phenols and altered colour.
  • The bruising of the olive fruit during harvesting downgrades the quality of the olive oil, particularly in the event that the extraction of the olive oil is delayed. For this reason, it is recommended that the olives collected from nets after they have dropped naturally must not be left lying on the nets for more than 15 days.
  • The transportation of the olive fruit and its storage for many hours before the extraction at high temperature and insufficient ventilation affects negatively the quality of the olive oil. Yucca sacks provide relatively good ventilation as opposed to plastic sacks, which must not be used. More sufficient airing is provided in crates, which constitute the best means of transportation and storage of the olive fruit. Sacks must be kept in a cool and properly ventilated place and the extraction of the olive oil must be completed as soon as possible (in less than 24 hours).


Basic types of standardized olive oil

Standardized olive oil is supplied for consumption in four basic types, the names of which correspond to their physicochemical and organoleptic characteristics that are determined by Regulations of the International Olive Council and the European Union:

  • extra virgin olive oil
  • virgin olive oil
  • olive oil composed of refined olive oils and virgin olive oils
  • olive-pomace oil


Organoleptic assessment – classification of olive oil

The organoleptic assessment is the detection and description of qualitative and quantitative characteristics of smell and flavor of olive oil.

Positive qualities include: fruity, bitter, spicy.

Negative qualities include: atrojado/sediments, mould/damp, winey-vinegary/acid-sour, metallic, rancid etc.


Olive oil alterations

The main alterations that olive oil will incur are hydrolysis and oxidation.

Hydrolysis or hydrolytic rancidity occurs mainly before the extraction of olive oil from the crop, while oxidation or oxidative rancidity occurs mainly after the production of olive oil and more particularly, when olive oil is stored under inappropriate storage conditions.

Hydrolysis is linked to an increase in acidity and change in the flavour. Humidity, temperature, ferments and various microorganisms are some of the factors affecting hydrolysis of the olive oil.

Oxidation or oxidative rancidity results in an alteration of the olive oil organoleptic qualities (smell, flavour) and a change in its physical qualities such as its viscosity. The main factors affecting oxidation are oxygen (air), high temperature, light and metals.


Risks for olive oil quality

In this case, danger is considered the condition or the factor that may render olive oil unsuitable for consumption or have a negative effect on the consumer’s health.

The types of dangers that may affect, downgrade or even alter the olive oil are:

a. Chemical dangers, among which the most important are:

  • Pesticide residues.
  • Heavy metals, the presence of which in the olive oils is due to their contact with the metallic parts of the olive mill machinery, tanks, storage and transportation containers or their cross-contamination during the production stage.
  • Environmental pollutants
  • Dangerous substances from packaging materials
  • b. Natural dangers, which mainly involve the presence of foreign objects such as glass fragments, plastic and metal pieces, hair, dust, dirt, impurities etc.


    Food safety and hygiene

    The European Union, in order to make sure that the products produced or transferred among its member states are healthy and safe for the consumers, takes measures with mandatory implementation in all food industries and businesses and issues regulations for inspection authorities of every member state. Food safety is based on two axes:

    1. HACCP studies (Hazard Analysis Critical Control Point)
    2. Guides (manuals) of Proper Hygiene Practices, which describe food hazards and relevant hygiene regulations.

    There is also the International Organization for Standardization (ISO), where many national standardization organizations from corresponding countries participate (Greece: ELOT).



    Traceability in food is a new field for the Food Industry and aims to control and certify the quality of the whole chain of production and commercialization of food products in every step of their production, from the point of origin of the raw material until the shelf and the plate of the consumers.


    Selection of raw materials (olive oil, supplementary materials, packaging materials)

    The supply of safe raw materials, packaging materials and supplementary materials with recorded and agreed upon specifications is of great importance.


    Olive oil authenticity

    Olive oil authenticity is determined by modern methods of molecular biology.


    Olive oil labelling

    Mandatory labelling specifications include:

    • Mandatory designation of origin (solely for extra virgin olive oil and virgin olive oil)
    • Quality category designation with descriptions on the category of the oil: extra virgin olive oil, virgin olive oil, olive oil composed of refined olive oils and virgin olive oils, olive-pomace oil.

    The identification of the origin in regional and local level is allowed only in the cases of PDO and PGI products.

    Optional labelling indications include:

    • first cold pressing
    • cold extraction
    • indications of organoleptic properties referring to taste and/or smell (fruity, bitter, spicey etc)
    • indication of the acidity


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