263 
 

Journal homepage: www.fia.usv.ro/fiajournal 
Journal of Faculty of Food Engineering,  

Ştefan cel Mare University of Suceava, Romania  
Volume XIII, Issue 3  – 2014, pag. 263 - 266 

 

 
VI RGIN O L IV E OIL ADU LTE RAT ION W ITH OTHER EDIB LE O ILS: 

IN FLU ENCE OF S UB ST I TU T ION ON PHYS ICO CH EMIC AL PROPE RTI ES  

 
*Mircea OROIAN1, Ana LEAHU1 

 
1Faculty of Food Engineering, Stefan cel Mare University of Suceava, Romania 

m.oroian@fia.usv.ro 
*Corresponding author 

Received September 7th 2014, accepted September 16th 2014 
 

 
Abstract:Adulteration is a common practice in the field of virgin olive oil industry because of its 
greater demand at European and international level. The olive oil represents around of 4% of the 
edible oil at international level.The aim of this paper is to study the influence of olive oil adulteration 
by substitution with other types of edible oils (sunflower, corn and groundnut) in different percentages 
(10%, 20%, 30%, 40% and 50%, respectively). The physicochemical properties studied were: density, 
refraction index and saponification index. The suitable parameter for the adulteration identification is 
the density, at percentages of substitution greater than 5% it can be observed that the parameter 
values is getting out of the domain from the EU regulations. The refractive index is not a proper tool 
for the adulteration identification, because its values are in the normal range in all the substitutions 
levels. The saponification index can be used for the identification of virgin olive oil adulteration with 
sunflower and corn oils in substitutions greater than 30%. 
 
Keywords:olive oil, adulteration, substitution, physicochemical properties 
 
 
1. Introduction 
 
Extra virgin olive oil is obtained from the 
olive fruit named Olea europaea. The 
extra virgin oil (EVOO) is extracted by 
only mechanical procedure without 
application of refining process [1]. The 
EVOO is practically the only vegetable oil 
that can be consumed directly in its raw 
state as well as it contains important 
nutritional elements (fatty acids, vitamin, 
sterols, etc.) [2]. The quality of olive oil 
ranged from the high quality of EVOO to 
the low quality olive pomace oil [3]. It is 
one of the primary ingredients of the 
Mediterranean diet [4].  
 Adulteration of food products 
involves the replacement of high-cost 
ingredients with lower grade and cheaper 
substitutes [5]. Due to its sensory quality 
andnutritional benefits extra-virgin olive  

 
 
 
 
oil is often adulterated withless expensive 
oils. Adulteration of olive oil is a serious 
problemfor regulatory agencies, oil 
suppliers and could also threat healthof 
consumers. The substitution of adulteration 
of EVOO with cheaper ingredients is not 
only economic fraud, but may also on 
occasion have severe health implications 
for consumers [6]. Because of the high 
value of EVOO, it can be adulterated with 
other oils of lower commercial value. The 
most common adulterants found in EVOO 
are refined olive oil, seed oils and nut 
oils.Actually, blend edible oils can be 
prepared only forsuitable products, but if 
the resulting blend deviates from the 
mixture proportions given on the label, or 
if the blend is traded as genuine, it means 
the oil is adulterated [7,8]. 



Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava 
Volume XIII, Issue 3 – 2014 

 

Mircea OROIAN, Ana LEAHU, Virgin olive oil adulteration with other edible oils: influence of substitution on 
physicochemical properties, Food and Environment Safety, Volume XIII, Issue 3 – 2014, pag. 263 – 266 

264 
 

The aim of this study is to investigate the 
influence of virgin olive oil substitution 
with other edible oils (sunflower, corn and 
groundnut oils) on the physicochemical 
parameters. 
 
2. Materials and methods  
 
Materials 
Olive oil, sunflower oil, corn oil and 
groundnut oil were purchased from the 
local market of Suceava.  
 
Methods 
Density measurements 
Density (ρ) of the oils samples was 
measured using pycnometer with an 
accuracy 10−4 gm/cm3. The calibration of 
pycnometer was made with ultrapure 
water. Temperature was kept constant 
within ±0.1 °C using PID controller and 
circulating water using thermo static-fluid 
bath. 
 
Refraction index 
The refraction index of the analysed 
samples was measured using an Abbe 
refractomer Leica at 20 °C. 
 
Saponification index 
Saponification value is expressed by 
potassium hydroxide, in mg, required to 
saponify one gram of fat [9]. It depends on 
the kind of fatty acid contained in the fat. 
The sample is first saponified by adding 
0.5 mol/L potassium hydroxide ethanol, 
and then the excessive potassium 
hydroxide is titrated with 0.5 mol/L 
hydrochloric acid until the end point is 
reached. The reactions which occur are: 
C3H5(OOCR)3 + 3KOH      3RCOOK + 

C3H5(OH)3 
3. Results and discussions 

The influence of different percentage of 
olive oil substitution of its 
physicochemical properties has been 
studied. Firstly, the olive oil purchased 

from the local market of Suceava was 
studied to see if the density, refraction 
index and saponification index, 
respectively, are according to the range 
established by the EU regulations [10]. 
The density of virgin olive oil must range 
between 0.914 and 0.919 g/cm³, the 
refraction index must range between 1.467 
and 1.470 and the saponification index 
must range between 184 and 196. In the 
table 1 are presented the density, refraction 
index and saponification index of virgin 
olive oil purchased from the local market. 
 

Table 1. 
Physicochemical parameters of virgin olive oil 

Parameter Value 
Density 0.915 g/cm3 
Refraction index 1.467 
Saponification index 187.51 
 
According to the values presented to the 
table 1, the virgin olive oil meets the 
threshold set by the EU regulations [10].   
 
Substitution influence on the virgin olive 
oil density 
 
In table 2 are presented the evolution of 
virgin olive oil density with different 
percentages substitution.  

 
Table 2. 

Oil samples density: A- virgin olive oil 
substituted with sunflower oil, B- virgin olive oil 
substituted with corn oil and C – virgin olive oil 

substituted with groundnut oil 
Substitution 
percentage 

A 
(g/cm3) 

B 
(g/cm3) 

C(g/cm3
) 

0 0.9150 0.9150 0.9150 
5% 0.9204 0.9250 0.9350 

10% 0.9225 0.9252 0.9350 
20% 0.9226 0.9261 0.9354 
30% 0.9227 0.9271 0.9356 
40% 0.9230 0.9280 0.9359 
50% 0.9235 0.9282 0.9365 

According to the EU regulations [10], the 
virgin olive oil density must range between 



Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava 
Volume XIII, Issue 3 – 2014 

 

Mircea OROIAN, Ana LEAHU, Virgin olive oil adulteration with other edible oils: influence of substitution on 
physicochemical properties, Food and Environment Safety, Volume XIII, Issue 3 – 2014, pag. 263 – 266 

265 
 

0.914 and 0.919 g/cm³. It can be observed 
that the substitution of the virgin olive oil 
with other types of edible oil with 5%, the 
density is increasing greater than the 
maximum allowable value for the density 
(0.919 g/cm3). The highest density value 
was observed in the case of the sample C 
(virgin olive oil substituted with 50% 
groundnut oil). It can be observed a 
positively correlation between the 
substitution of virgin olive oil and density. 
 
Substitution influence on the virgin olive 
oil refractive index 
 
In figure 1 is presented the evolution of the 
virgin olive oil refractive index – pure and 
substituted. 
 

 
Fig. 1. Refractive index evolution: A- virgin olive 
oil substituted with sunflower oil, B- virgin olive 
oil substituted with corn oil and C – virgin olive 

oil substituted with groundnut oil 
 
According to the EU regulations [10], the 
refractive index must range between 1.467 
and 1.470. The EVOO substation with 
groundnut oil (in all the substitution 
percentages) decreases the value of the 
refractive index. The substitution of EVOO 
with 10%, 20%, 30%, 40% and 50% corn 
oil and sunflower oil maintain the 
refractive index at normal levels. The 
substitution of EVOO with sunflower oil 

had the highest influence on the refractive 
index.  

 
Substitution influence on the virgin olive 
oil saponification index 
 
In table 3 is presented the evolution of the 
saponification index of the virgin olive oil. 

 
Table 3 

Oil samples saponification index:  
A- virgin olive oil substituted with sunflower oil,  
B- virgin olive oil substituted with corn oil  
C – virgin olive oil substituted with groundnut oil 
 

Substitution  
percentage (%) A B C 

0 187.5 187.5 187.5 
5 206.1 200.2 185.2 

10 216.2 203.1 183.2 
20 223.2 205.8 180.9 
30 228.6 217.8 178.2 
40 230.2 219.2 175.4 
50 232.5 223.6 176.1 

 
The values of saponification index for the 
virgin olive oil, according to the EU 
regulations [10], range between 184 and 
196. The most visible adulteration is that 
with sunflower oil, which at a percentage 
of substitution of 50%, the saponification 
index is reaching the value of 240. In 
smaller percentages, the virgin olive oil 
adulterated with sunflower oil is 
maintained the saponification index value 
closer to the normal ones. For observing 
the adulteration of virgin olive oil with 
sunflower oil is needed at least a 
substitution percentage of 30%. In the case 
of EVOO adulteration with corn oil, the 
saponification index values are smaller 
than in the case of sunflower oil, but the 
adulteration can be observed if the 
substitution percentage is greater than 
30%. 
In the case of EVOO adulteration with 
groundnut oil, the saponification index 
cannot be used as an indicator, because the 
values of the adulterated samples are in the 
range of EVOO. 

1.4655

1.466

1.4665

1.467

1.4675

1.468

1.4685

1.469

1.4695

0 20 40 60

R
ef

ra
ct

iv
e 

in
de

x

Substitution percentage (%)

A

B

C



Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava 
Volume XIII, Issue 3 – 2014 

 

Mircea OROIAN, Ana LEAHU, Virgin olive oil adulteration with other edible oils: influence of substitution on 
physicochemical properties, Food and Environment Safety, Volume XIII, Issue 3 – 2014, pag. 263 – 266 

266 
 

 
4. Conclusions 
 
Food adulteration is a common practice for 
the olive oil industry due to its great 
demand at European and international 
level because of the great positively 
influence of it on the human body. The 
adulteration of virgin olive oil with 
different edible oils can be observed using 
the values for density, refractive index and 
saponification index. The substitution of 
virgin olive oil with sunflower can be 
observed using: the density determination 
for substitutions greater than 5%, the 
saponification index greater than 5%, 
while the refractive index determination 
cannot be used. In the case of the 
substitution of EVOO with corn oil, the 
density and saponification index can be 
used for the identification of the 
adulteration greater than 5%. The 
saponification index cannot be used for the 
identification of the substitution of EVOO 
with groundnut oil.  
 
5. References 
 
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virgin oil adulteration using a volatammetric 
e-tongue, Computers and Electronics in 
Agriculture, 108, 148-154, (2014)  

[2] JABEUR, H., ZRIBI, A., ABDELHEDI, R., 
BOUAZIZ, M., Effect of olive storage 
conditions on chemical olive oil quality and 
the effective role of fatty acids alkyl esters in 
checking olive oils authenticity, Food 
Chemistry, 169, 289-296, (2015)

 
[3] TSIMIDOU, M. Z., Olive oil quality. In: 

Boskou, D., (Ed.), Olive oil: Chemistry and 
Technology, second ed. Champaign, Illinois: 
AOCS Publishing, 93-112, (2006) 

[4] PSALTOPOULOU, T., NASKA, A., 
ORFANOS, P., TRICHOPOULOS, D., 
MOUNTOKALAKIS, T., TRICHOPOULOU, 
A., Olive oil, the Mediterranean diet, and 
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Clinical Nutrition, 80, 1012–1018, (2004) 

[5] TAY, A., SINGH, R. K., KRISHNAN, S. S., 
GORE, J. P., Authentication of olive oil 
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transform infrared spectroscopy.LWT-Food 
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[6] TORECCILLA, J. S., ROJO, E., 
DOMINGUEZ, J. C., RODRIGUEZ, F., 
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[7] ULBERTH, F., BUCHGRABER, M., 
Authenticity of fats and oils. European 
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[8] GURDENIZ, G., OZEN, B., Detection of extra-
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[9] ISO 3657 – Saponification value of fat and oil 
[10] Commission Implementing Regulation (EU) 

No 1348/2013 of 16 December 2013 
amending Regulation (EEC) No 2568/91 on 
the characteristics of olive oil and olive-
residue oil and on the relevant methods of 
analysis