The presentation describes two portable battery operated electronic systems to make measurements of free acidity, peroxide value and total phenol content in olive oil. If you want to know more about this topic, please read: [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. http://dx.doi.org/10.1109/JSEN.2014.2321323 [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. http://dx.doi.org/10.1016/j.mejo.2014.07.006 [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. http://dx.doi.org/10.1016/j.jfoodeng.2014.08.015

1. 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_Grossi

2. European Union represents the biggest producers of olive oil
in the world (about 80% of the world production).
Olive oil market

3. 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)

4. Depending on the measured quality parameters, the olive oil
can be classified according to different categories.
ProductProduct Free acidityFree acidity Peroxide valuePeroxide value
Extra Virgin Olive OilExtra Virgin Olive Oil ≤≤ 0.8 %0.8 % ≤≤ 2020
Virgin Olive OilVirgin Olive Oil 0.8 % - 2 %0.8 % - 2 % ≤≤ 2020
Lampante Olive OilLampante Olive Oil > 2 %> 2 % --
Refined Olive OilRefined Olive Oil ≤≤ 0.3 %0.3 % ≤≤ 55

5. 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:
1.Quick and simple measurements that can be performed also by
non trained workers
2.The technique must be implemented in the form of a portable
electronic system
3.The electronic system must be built with low cost electronics

6. • 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.
Measurement of free acidity in olive oil
• In presence of the reagent the free fatty acid molecules are
ionized leading to an increase of the electrical conductance (Gm)
of the emulsion.

7. • The electrical conductance (Gm) of the emulsion is measured
and the olive oil free acidity is estimated.
4 3
828.3561.8822.1 AcidityAcidityGm −+−=

8. A portable battery-operated electronic system has been built
To watch a video of the instrument performing a measure:
https://www.youtube.com/watch?v=2C55F4w8mBs&feature=youtu.be
To watch a video of the instrument performing a measure:
https://www.youtube.com/watch?v=2C55F4w8mBs&feature=youtu.be
To watch a video of the instrument performing a measure:
https://www.youtube.com/watch?v=2C55F4w8mBs&feature=youtu.be
To watch a video of the instrument performing a measure:
https://www.youtube.com/watch?v=2C55F4w8mBs&feature=youtu.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

10. A Led is used to provide the incident radiation and a photodiode to
measure the intensity of the transmitted radiation
Total phenol content
Reagent: 1ml of Folin-Ciocalteu
reagent + 1ml of Na2CO3 15% +
13ml of distilled water
λpeak,LED = 835 nm
Peroxide number
Reagent: 8ml of ferrous ion
oxidation xylenol orange (FOX)
+ 7ml of distilled water
λpeak,LED = 569 nm

11. A portable battery-operated electronic system has been built

12. 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

13. 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.