Embedded portable instruments for olive oil quality analysis

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Embedded portable instruments for olive oil
quality analysis determination of free acidity,
peroxide value and total phenol content
Marco Grossi Department of Electrical Energy and
Information Engineering University of Bologna,
Italy http//www.researchgate.net/profile/Marco_Gr
ossi
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Olive oil market
European Union represents the biggest producers
of olive oil in the world (about 80 of the world
production).
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Olive oil quality
The determination of olive oil quality is carried
out by means of laboratory analytical methods and
sensorial analysis. Free acidity (expressed as
grams of oleic acid in 100mg of oil) is an
indicator of the quality of the olives used to
produce the oil and the procedures in the oil
production. Peroxide value (expressed as
milliequivalents of O2 in 1kg of oil) is an
indicator of the oil oxidation. Bad storage
conditions lead to increase of peroxide
value. Total phenol content (expressed as mg of
gallic acid in 1kg of oil) Phenols are soluble
polar compounds responsible for the oil
organoleptic properties and are important due to
their anti-oxidant properties (beneficial for
human health)
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Depending on the measured quality parameters, the
olive oil can be classified according to
different categories.
Product Free acidity Peroxide value
Extra Virgin Olive Oil 0.8 20
Virgin Olive Oil 0.8 - 2 20
Lampante Olive Oil gt 2 -
Refined Olive Oil 0.3 5
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• Reference techniques for olive oil quality
  analysis are generally complex and need trained
  personnel and a laboratory environment.
• Such techniques are not suitable to be
  implemented in olive oil production centers also
  due to the use of toxic reagents.
• To improve the quality assessment of olive oil
  with in-situ measurements the following
  requirements are needed
• Quick and simple measurements that can be
  performed also by non trained workers
• The technique must be implemented in the form of
  a portable electronic system
• The electronic system must be built with low cost
  electronics

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Measurement of free acidity in olive oil

• A polypropylene vial modified to feature two
  stainless steel electrodes is filled with 15 ml
  of hydroalcoholic solution (9ml ethanol 6ml
  distilled water).
• 1ml of the olive oil under test is added to the
  reagent and all is stirred to create the emulsion.

• In presence of the reagent the free fatty acid
  molecules are ionized leading to an increase of
  the electrical conductance (Gm) of the emulsion.

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• The electrical conductance (Gm) of the emulsion
  is measured and the olive oil free acidity is
  estimated.

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A portable battery-operated electronic system has
been built
To watch a video of the instrument performing a
measure https//www.youtube.com/watch?v2C55F4w8
mBsfeatureyoutu.be
To watch a video of the instrument performing a
measure https//www.youtube.com/watch?v2C55F4w8
mBsfeatureyoutu.be
To watch a video of the instrument performing a
measure https//www.youtube.com/watch?v2C55F4w8
mBsfeatureyoutu.be
To watch a video of the instrument performing a
measure https//www.youtube.com/watch?v2C55F4w8
mBsfeatureyoutu.be
9
Measurement of peroxide value and total phenol
content in olive oil
The aqueous reagent is mixed with 0.5ml of the
oil under test to create an emulsion The optical
absorbance is measured and used to estimate the
parameter of interest
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A Led is used to provide the incident radiation
and a photodiode to measure the intensity of the
transmitted radiation
Peroxide number Reagent 8ml of ferrous ion
oxidation xylenol orange (FOX) 7ml of distilled
water ?peak,LED 569 nm
Total phenol content Reagent 1ml of
Folin-Ciocalteu reagent 1ml of Na2CO3 15
13ml of distilled water ?peak,LED 835 nm
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A portable battery-operated electronic system has
been built
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Peroxide value correlation between the value
measured with the reference technique and the
intensity of transmitted radiation Total phenol
content correlation between the value measured
with the reference technique and the logarithm of
the intensity of transmitted radiation
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References
1 Grossi M., Di Lecce G., Gallina Toschi T.,
Riccò B. (2014). Fast and accurate determination
of olive oil acidity by electrochemical impedance
spectroscopy. IEEE Sensors Journal, 14 (9),
2947-2954. 2 Grossi M., Di Lecce G., Gallina
Toschi T., Riccò B. (2014). A novel
electrochemical method for olive oil acidity
determination. Microelectronics Journal, 45,
1701-1707. 3 Grossi M., Di Lecce G., Arru,
M., Gallina Toschi T., Riccò B. (2015). An
opto-electronic system for in-situ determination
of peroxide value and total phenol content in
olive oil. Journal of Food Engineering, 146, 1-7.