obtained VOO which still contains residues of the vegetable material (olive pulp,
etc.) and emulsified water. For practical reasons, the official sensory method clusters
the two descriptors “fusty” and “muddy” into one category. The defect named
“musty-humid-earthy” comes from olives with high development of fungi and
yeasts, or those collected from the ground in contact with earth or mud, or even
when the washing phase is not carried out correctly (dirty washing water with
excessive soil residues). Musty defect occurs when mould naturally present on the
olive skin develops, especially under humid conditions. In certain cases, alcoholic
fermentation can take place, resulting in the appearance of the “winery-vinegary”
defect, which can be easily recognised due to the similarity with vinegar pungent
note. It is correlated with high levels of acetic acid, ethyl acetate and ethanol, due to
yeast or Acetobacter development. Rancid is a typical defect of olive storage, due to
lipid oxidation. This is common to all vegetable oils or generally fats, and its
intensity is related to the fatty acid composition and presence of antioxidants as
well as storage conditions (light, oxygen exposure and high temperature). A defect
named “frostbitten olives”, or “wet wood”, is due to the presence of frozen olives; it
is encountered in areas where low overnight temperatures before harvest damage the
olive fruits due to water crystallisation. Its sensory impact resembles the odour of
wet wood, sometimes similar to chocolate aroma, in the case of intense damage.
Other negative attributes can be added to the sensory evaluation form during the
panel test. In the case of negative attributed listed as “others”, a minimum number of
assessors detecting a specific defect are required to judge the oil as defective.
According to the IOC norm, widely accepted in producing and importing countries, VOO sensory assessment is carried out by a panel of at least eight trained
judges, who are required to pass specific training and assessment. Training of future
panellists includes tests to evaluate their ability to detect basic flavours and adequately describe olive oil sensory defects. Accreditation of sensory testing laboratories is critical to guarantee that the panel act properly and give robust and valid
results. The official method describes the settings of the laboratory, the light
conditions, room and sample temperatures and the specifics for the blue glass
designed for olive oil tasting, as well as the heater conditions (the sample must be
tested at a temperature of 28 Æ 2
C) and the sheet to record the results. The positive
and negative attributes are scores on a 10 cm unstructured scale. In case of sensory
defects that do not belong to one of the five classes previously mentioned, the
assessors can describe it, using an agreed vocabulary. For the positive attribute of
“fruity”, the assessor is asked to specify whether it is “green” or “ripe” fruity. The
importance of using a panel instead of evaluation of single experts comes from the
fact that subjectivity in the assessment should be removed as much as possible. For
this purpose, appropriate statistical methods are used, e.g. application of the median
instead of the mean value for each attribute.
In addition to virgin olive oils of various origins, there is a niche market for
EVOOs with typical characteristics. These oils belong to the Protected Designation
of Origin (PDO) labels, and they have to comply with additional EU regulations. In
terms of sensory assessment, the disciplinary of the product can include compulsory
presence of intensity limits for some attributes, e.g. almond, artichoke, fig leaf, etc.
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N. Caporaso and D. Boskou
etc.) and emulsified water. For practical reasons, the official sensory method clusters
the two descriptors “fusty” and “muddy” into one category. The defect named
“musty-humid-earthy” comes from olives with high development of fungi and
yeasts, or those collected from the ground in contact with earth or mud, or even
when the washing phase is not carried out correctly (dirty washing water with
excessive soil residues). Musty defect occurs when mould naturally present on the
olive skin develops, especially under humid conditions. In certain cases, alcoholic
fermentation can take place, resulting in the appearance of the “winery-vinegary”
defect, which can be easily recognised due to the similarity with vinegar pungent
note. It is correlated with high levels of acetic acid, ethyl acetate and ethanol, due to
yeast or Acetobacter development. Rancid is a typical defect of olive storage, due to
lipid oxidation. This is common to all vegetable oils or generally fats, and its
intensity is related to the fatty acid composition and presence of antioxidants as
well as storage conditions (light, oxygen exposure and high temperature). A defect
named “frostbitten olives”, or “wet wood”, is due to the presence of frozen olives; it
is encountered in areas where low overnight temperatures before harvest damage the
olive fruits due to water crystallisation. Its sensory impact resembles the odour of
wet wood, sometimes similar to chocolate aroma, in the case of intense damage.
Other negative attributes can be added to the sensory evaluation form during the
panel test. In the case of negative attributed listed as “others”, a minimum number of
assessors detecting a specific defect are required to judge the oil as defective.
According to the IOC norm, widely accepted in producing and importing countries, VOO sensory assessment is carried out by a panel of at least eight trained
judges, who are required to pass specific training and assessment. Training of future
panellists includes tests to evaluate their ability to detect basic flavours and adequately describe olive oil sensory defects. Accreditation of sensory testing laboratories is critical to guarantee that the panel act properly and give robust and valid
results. The official method describes the settings of the laboratory, the light
conditions, room and sample temperatures and the specifics for the blue glass
designed for olive oil tasting, as well as the heater conditions (the sample must be
tested at a temperature of 28 Æ 2
C) and the sheet to record the results. The positive
and negative attributes are scores on a 10 cm unstructured scale. In case of sensory
defects that do not belong to one of the five classes previously mentioned, the
assessors can describe it, using an agreed vocabulary. For the positive attribute of
“fruity”, the assessor is asked to specify whether it is “green” or “ripe” fruity. The
importance of using a panel instead of evaluation of single experts comes from the
fact that subjectivity in the assessment should be removed as much as possible. For
this purpose, appropriate statistical methods are used, e.g. application of the median
instead of the mean value for each attribute.
In addition to virgin olive oils of various origins, there is a niche market for
EVOOs with typical characteristics. These oils belong to the Protected Designation
of Origin (PDO) labels, and they have to comply with additional EU regulations. In
terms of sensory assessment, the disciplinary of the product can include compulsory
presence of intensity limits for some attributes, e.g. almond, artichoke, fig leaf, etc.
236
N. Caporaso and D. Boskou