pág. 45
Artículo científico
Volumen 6, Número 2, julio - diciembre, 2023
Recibido: 19-07-2023, Aceptado: 11-10-2023
https://doi.org/10.46908/tayacaja.v6i2.213
Kinetics of the oxidation of oils derived from Peruvian foods rich in
ω-3 and ω-6 fatty acids using the Rancimat method
Cinética de la oxidación de aceites derivados de alimentos peruanos ricos en ácidos
grasos ω-3 y ω-6 mediante el método Rancimat
Eudes Villanueva López
Universidad Nacional Autónoma de Tayacaja Daniel Hernández Morillo, Perú
eudesvillanueva@unat.edu.pe
Elza Berta Aguirre Vargas
Universidad Nacional del Santa, Perú
eaguirre@uns.edu.pe
Beetthssy Zzussy Hurtado-Soria
Universidad Nacional Autónoma de Tayacaja Daniel Hernández Morillo, Perú
beetthssy.hurtado@unat.edu.pe
Lucia Ruth Pantoja Tirado
Universidad Nacional Autónoma de Tayacaja Daniel Hernández Morillo, Perú
luciapantoja@unat.edu.pe
Harold Pawel Johao Ore Quiroz
Universidad Nacional Autónoma de Tayacaja Daniel Hernández Morillo, Perú
haroldore@unat.edu.pe
Ronald Ortecho Llanos
Universidad Nacional Autónoma de Tayacaja Daniel Hernández Morillo, Perú
ronaldortecho@unat.edu.pe
Adiel Álvarez Ticllasuca
Universidad Nacional Autónoma de Tayacaja Daniel Hernández Morillo, Perú
adielalvarez@unat.edu.pe
José Torres – Huamaní
Universidad Nacional Autónoma de Tayacaja Daniel Hernández Morillo, Perú
josetorres@unat.edu.pe
ABSTRACT
Peru has several foods with high lipid content (especially oils), rich in omega fatty acids (ω-3 and ω-6) that are widely
studied for their anti-inflammatory (ω-3) and pro-inflammatory (ω-6) effects. However, ω-3 and ω-6 are susceptible
to oxidation resulting in accelerated deterioration of the oils. The objective of this work was to determine the
oxidative stability index (OSI) of vegetable (seeds) and animal (anchoveta) oils from Peru, with high ω-3 and ω-6
contents, in order to compare oxidation kinetic parameters and shelf life. For this purpose, the Rancimat accelerated
oxidation method was used, whose working parameters were: air flow (F = 25 L/h), sample weight (M = 3 g) and
temperature range (T = 60-140 °C). The results indicated that the OSI values, as well as the shelf-life projection (T
= 25°C) were in the following order: olive oil > chestnut > sesame > sacha inchi > flaxseed > chia > fish. The kinetic
parameters of rate constant (k), activation energy (Ea), enthalpy (∆H), entropy (∆S) and temperature acceleration
factor (Q10) varied significantly among the oils (p < 0.05). The comparison of the kinetic behavior of the studied
samples is key for the development of new products with longer shelf life and increased nutritional value.
Keywords: Vegetable oils; oxidative stability; omegas; autoxidation; rancimat.
pág. 46
Artículo científico
Volumen 6, Número 2, julio - diciembre, 2023
Recibido: 19-07-2023, Aceptado: 11-10-2023
https://doi.org/10.46908/tayacaja.v6i2.213
RESUMEN
Perú posee varios alimentos con alto contenido lipídico (especialmente aceites), ricos en ácidos grasos omega (ω-3
y ω-6) que son ampliamente estudiados por sus efectos antiinflamatorios (ω-3) y proinflamatorios (ω-6). Sin
embargo, los ω-3 y ω-6 son susceptibles a la oxidación, lo que provoca un deterioro acelerado de los aceites. El
objetivo de este trabajo fue determinar el índice de estabilidad oxidativa (OSI) de aceites vegetales (semillas) y
animales (anchoveta) del Perú, con altos contenidos de ω-3 y ω-6, para comparar parámetros cinéticos de oxidación
y vida útil. Para ello, se utilizó el método de oxidación acelerada Rancimat, cuyos parámetros de trabajo fueron: flujo
de aire (F = 25 L/h), peso de la muestra (M = 3 g) y rango de temperatura (T = 60-140 °C). Los resultados indicaron
que los valores de OSI, así como la proyección de la vida útil (T = 25°C) seguían el siguiente orden: aceite de oliva
> castaña > sésamo > sacha inchi > linaza > chía > pescado. Los parámetros cinéticos de constante de velocidad (k),
energía de activación (Ea), entalpía (∆H), entropía (∆S) y factor de aceleración de la temperatura (Q10) variaron
significativamente entre los aceites (p < 0,05). La comparación del comportamiento cinético de las muestras
estudiadas es clave para el desarrollo de nuevos productos con mayor vida útil y mayor valor nutritivo.
Palabras clave: Aceites vegetales; estabilidad oxidativa; omegas; autooxidación; rancimat.
INTRODUCCIÓN
Oils from vegetable seeds and marine sources are
indispensable in the human diet, since many of them
contain essential fatty acids, which means that this
type of raw material represents more than 75% of the
total lipids consumed in the world (Jinadasa et al.,
2022). Among the functions of oils are to provide
energy, maintain normal body temperature, protect
body tissues, transport fat-soluble vitamins, among
other functions (Orsavova et al., 2015). With
population growth and economic development, edible
vegetable oils have experienced a remarkable increase
due to their important roles in health protection and
disease prevention (Yang et al., 2018). Between
January and August 2021, Peru exported 566,337 kilos
of vegetable oils for an FOB value of US$ 6,196,604.
These figures reveal a moderate increase from the
464,672 kilos exported in the same period of 2020 for
US$ 5,405,797 (Ramos, 2021). The main destination
of these shipments was France, including avocado,
sacha inchi, walnut, Palo de Rosa, chia and jojoba oils.
The Netherlands followed with US$1,126,902,
Taiwan with US$ 747,663, Malaysia with
US$ 571,537, Spain with US$ 569,584, Germany with
US$ 308,866, the United Kingdom with US$228,487,
the United States with US$ 145,007, Colombia with
US$11,118, and others with smaller amounts that
together totaled US$ 455,358 (Ramos, 2021). On the
other hand, oils of marine origin such as fish oil differ
from other vegetable and animal oils due to their high
content of polyunsaturated fatty acids (PUFAs)
(Özyurt et al., 2020). Peru produces on average 230
000 tons of fish oil per year, representing 23% of the
world production (Fréon et al., 2017). It has been
reported that ω-3 fatty acids, especially EPA
(eicosapentaenoic acid, C20:5, ω-3) and DHA
(docosahexaenoic acid, C22: 6, ω-3), tend an anti-
inflammatory role allowing it to develop an important
role in the prevention of coronary artery disease, some
types of cancer, rheumatoid arthritis, cellular aging,
and improvement of neurological functions in children
(Bi et al, 2019; Rahmawaty & Meyer, 2020; Shahidi
& Ambigaipalan, 2018).
In the human body, dietary linoleic acid (ω-6) is
converted into arachidonic acid (ω-6), which is an
essential part of membrane phospholipids. These
molecules are then converted to prostaglandin H2 by
the enzyme’s cyclooxygenase-1 (COX-1) and
cyclooxygenase-2 (COX-2). The conversion of
prostaglandin H2 to PGE2 as a proinflammatory
eicosanoid contributes to the development of
metastasis and tumor growth through a different
mechanism, including inhibition of apoptosis, cell
proliferation and invasion. For example, high levels of
PGE2 have been demonstrated in malignant prostate
cancers (compared to their benign counterparts)
(Kobayashi et al., 2006). Recent studies indicate that
linoleic acid, at least in part, may be influencing the
inhibition of expression of two genes (WIF-1 and
WT1) involved in the Wnt signaling pathway as the
molecular basis for the formation and progression of
many types of cancer (Mohammadihaji et al., 2022).
The rancimat method is an accelerated deterioration
(oxidation) test carried out by heating samples in test
tubes at elevated temperatures. With the aid of an air
flow into the tubes, the samples undergoing oxidation
are bubbled and volatile chemicals such as acetic acid
and formic acid are withdrawn into a container of
distilled water through an outlet duct. This process
changes the conductivity of the distilled water and
allows the products of the oxidation process to be
monitored. The oxidation stability of part of the
pág. 47
Artículo científico
Volumen 6, Número 2, julio - diciembre, 2023
Recibido: 19-07-2023, Aceptado: 11-10-2023
https://doi.org/10.46908/tayacaja.v6i2.213
samples can be correlated with the so-called induction
time or oxidative stability index (OSI), measured in
hours, which elapses from the start of the test until the
secondary oxidation products increase the
conductivity dramatically in the vessel containing the
distilled water (Bär et al., 2021).
The great variety of lipid raw materials in Peru and the
possibility of deepening studies linked to PUFAs,
especially ω-3 and ω-6, for their wide nutritional
benefits, implies comparing them at a chemical level
(deterioration) for future technological applications in
the food industry. The objective of this work was to
determine and OSI of edible oils derived from
Peruvian foods rich in ω-3 and ω-6 fatty acids, such as
those derived from vegetable seeds and marine source
such as anchoveta oil, to compare their oxidation
kinetic parameters and shelf life using the accelerated
rancimat oxidation method.
METHODOLOGY
Samples and preparation of blends
Vegetable seeds were obtained from different regions
of Peru. Sacha inchi (Plukenetia volubilis L, variety -
Peanut INCA-1) was harvested from the San Martin
Region, Lamas province (06°25′00′′′S altitude and
76°32′00′′′W latitude); Chia (Salvia hispanica L.,
variety - Black) was obtained from Ancash region,
Yungay province (09° 08′ 20″ S altitude and 77° 44′
40″ W latitude); Chestnut (Bertholletia excelsa
H.B.K) was from Madre de Dios Region in the forests
of De Las Piedras district in Tambopata (12°35' 36" S
altitude and 69° 10' 35" W latitude); Linseed (Linum
usitatissimum L., variety - Brown) was obtained from
Ancash Region, Corongo province (8°30′34″S altitude
77°54′37″W latitude); Sesame (Sesamun indicum L.,
Variety - Venezuela 51) was obtained from San Martin
Region, Tarapoto district (6°29′39″S altitude and
76°22′11″W latitude). The oil from the mentioned
seeds was obtained by cold pressing (SEW-
EURODRIVE press model FA57/G, Germany) with a
screw speed of 40 rpm and maximum temperature of
40°C, the seeds had a humidity between 9 - 11 %
(Figure 1 and 2). The oil was kept for 30 days in a dark
flask under nitrogen atmosphere in a refrigerator
(BOSCH, model KAN58A, South Korea) at a
temperature of (5.00 ± 0.5°C) at the facilities of the
Agroindustrial Technological Research Institute of the
Universidad Nacional del Santa.
Regarding the olive oil (Olea Europea), they were
obtained from fruits "olives" (Variety - Criolla)
harvested in the Tacna Region, province of La Yarada
- Los palos (18°17′08″S altitude and 70°26′20″W
latitude). The conventional method of extra virgin
olive oil extraction was used, which consisted of three
main processes, which were crushing, malaxation and
centrifugation. Subsequently, stored under
refrigeration at a temperature of 5.0 ± 0.5°C. The fish
oil was from the anchoveta species (Engraulis
ringens), provided by the fish processing company
CFG-COPEINCA S.A.C. Chimbote, Peru.
Physico-chemical characterization
The acid number (AV) was determined by the titration
method defined in the official methods Cd 3d-63 of the
American Oil Chemists' Society (AOCS, 1993).
7Titration of the oil samples (10 g) dissolved in 50 mL
of previously neutralized chloroform–ethanol medium
(50:50 v/v) was applied, using a 0.1 N potassium
hydroxide (KOH) ethanolic solution as standard
reagent to a phenolphthalein endpoint. AV was
expressed as milligrams of KOH required to neutralize
the free fatty acids present in 1 g of the oil sample (mg
KOH/g).
AV= G x N x 56.1 / w (1)
Where: G is the titratable volume of KOH (mL), N is
the normal of KOH (0.1 N) and w is the weight of the
sample (g).
The refractive index (RI) was measured according to
method 921.08 (AOAC International, 2019) working
at 25 °C and using a digital A 24051 refractometer
(Rudolph Research Analytical, NJ, USA) kept at 20
°C.
The iodine value (IV) was determined by the Wijs
method, in accordance with method 993.20 (AOAC
International, 2019), 0.2 g of oil was dissolved with 10
mL of chloroform and 15 mL of Wijs reagent, after 45
min of rest 10 mL of potassium iodide 15% in 50 mL
of distilled water was added, proceeded to titrate with
sodium thiosulfate (0.1 N) with a brown to yellow
color change, 1 mL of 1% soluble starch was added
and titrated again with 0.1 N sodium thiosulfate until
the color changed from blue to white. IV was
expressed as mg I2/g.
IV = (B – M) x N x 12.65 / w (2)
pág. 48
Artículo científico
Volumen 6, Número 2, julio - diciembre, 2023
Recibido: 19-07-2023, Aceptado: 11-10-2023
https://doi.org/10.46908/tayacaja.v6i2.213
Where: B and M are the titratable volumes of sodium
thiosulfate (mL) for the blank and oil sample,
respectively. N is the sodium thiosulfate normal (0.1
N) and w is the sample weight (g).
The peroxides value (PV) was determined following
the Cd 8-53 method (AOCS, 1998) with
modifications, where 5 g of oil were dissolved in 30
mL of acetic acid-chloroform solution (60/40 v/v),
added 0. 5 mL of saturated potassium iodide was
added and allowed to stand for 1 min in the dark, then
30 mL of distilled water was added and stirred for 5
min. Finally, 0.5 mL of 1% starch solution was added
and titrated with 0.01 N sodium thiosulfate solution.
PV was expressed in milliequivalents of active oxygen
present in 1 kg of oil (mEqO2/kg).
PV= G x N x 1000 /w (3)
Where: G is the titratable volume of sodium
thiosulfate (mL), N is the normal of sodium thiosulfate
(0.01 N) and w is the weight of the sample (g).
The p-anisidine (p-AV) value was monitored using the
Cd 18-90 method (AOCS, 1998) with modifications,
two reagent dilutions were prepared, the first consisted
of the oil/isooctane mixture (0.5 g/25mL), and the
second was anisidine reagent/acetic acid (0.025 g/25
mL). Subsequently, the absorbances of the dilutions
were measured at 350 nm, according to the following
description:
p-AV= 25 x (1.2 x As - Ab)/w (4)
Where: As is absorbance of oil/isooctane minus
absorbance of pure isooctane. Ab is absorbance of the
oil/isooctane diluted in anisidine/acetic acid (1/1, v/v)
minus the absorbance of the anisidine/acetic acid
diluted in isooctane (1/1, v/v). w is the weight of the
oil (g).
Finally, the total oxidation value (TotOX) has been
determined as:
TotOX = 2PV + p-AV (5)
Fatty acid profile
The fatty acid composition of the oils was determined
according to the fatty acid methyl ester method n.
991.39 (AOAC,2005), which consisted of weighing
0.025 g of oil and reacting with 1.5 mL of NaOH 0.5
N at 90°C in a water bath (Foos, mode-loWB1024) for
5 min, then cooling to 30°C and adding 2. 0 mL of
boron trifluoride (BF3) heated to 100°C for 30 min,
again cooled by adding 1 mL of iso-octane and 5 mL
of saturated NaCl solution, all under stirring and
constantly covered with nitrogen. Identification of the
components was determined on gas chromatograph
(Shimadzu, model GC-2010, Japan), equipped with a
flame ionization detector (FID) and a Shimadzu AOC-
20Si autosampler. An SP Rt™ -2560 silica capillary
column (100 m x 0.25 mm with 0.20 μm film) was
used helium as carrier gas at a flow rate of 30 mL/min
and pressure of 261.5 kPa. Injection volume was 1 μL.
Injector temperature was programmed at 225°C (Split
mode) and detector at 250°C. Oven temperature was
programmed: initial temperature 100°C for 4 min, then
at 240°C with a rate of 3°C/min for 10 min.
Oxidative stability index (OSI) and shelf-life
The accelerated stability test was carried out in a
Rancimat equipment (Metrohm, model 743,
Switzerland) to evaluate the OSI (hours) of the
samples according to the AOCS Cd 12b-92 method.
Rancimat parameters were programmed at three
different reaction temperatures (100, 110 and 120 °C)
with an air flow (15 L/h) and constant sample weight
(3.00 ± 0.1 g). The temperatures were selected
according to the oxidation resistance of AO and VOO
(Jiang et al., 2020; Farhoosh et al., 2013). The OSI
values were inversely proportional to the temperatures
values and related according to the equation proposed
by Heidarpour and Farhoosh (2018):
Log (OSI)= α(T) + β (6)
Shelf-life prediction () was determined by
extrapolating the temperature to 25°C.
Autooxidation kinetics
The activation energy (Ea) was determined according
to:
󰇛󰇜󰇡󰇛󰇜
󰇢 󰇡
󰇢󰇡
󰇢 (7)
Where: R=8.314 J/mol K (universal gas constant), α*
is the degree of transformation of unsaturated
molecules and Z is factor of Arrhenius equation.
The entropy () and enthalpy () were
obtained by regressing Log (k/T) versus (1/T),
equation derived from the activated complex theory,
according to Heidarpour and Farhoosh (2018):
󰇡
󰇢 󰇣󰇡
󰇢 󰇡 
󰇢󰇤 󰇡
󰇢󰇡
󰇢 (8)
pág. 49
Artículo científico
Volumen 6, Número 2, julio - diciembre, 2023
Recibido: 19-07-2023, Aceptado: 11-10-2023
https://doi.org/10.46908/tayacaja.v6i2.213
Where: =1.380658 x 10-23 J/K (Boltzmann
constant), h=6.6260755 x 10-34 Js (Planck's constant)
and K = 1/OSI. The Gibbs free energy () was
calculated according to equation:
   (9)
The value of  was determined according to
Farhoosh (2007):
 = 
 (10)
Statistical analysis
Data processing was performed in Minitab statistical
software version 18 (Softonic, USA). Analysis of
variance (ANOVA) was used to determine significant
differences between treatment means using Tukey's
test (p<0.05). Means were calculated by triplicate
analysis of the samples.
Figure 1
Raw materials derived from vegetable seeds and fish
Figure 2
Vegetable seed oils from Peru: (a)chestnut, (b) sesame, (c) chia, (d) flaxseed, (e) olive and (f) sacha inchi
Physico-chemical characterization of Peruvian oils
The physical and chemical characteristics of the oils
are presented in Table 1, the composition of fatty acids
of unsaturated nature was presented mostly in chia,
sacha inchi, flaxseed and anchovy oils, these oils are
referenced for their high content of α-linolenic for
those of vegetable origin and DHA + EPA for those of
marine origin (Rodriguez et al., 2020; Aguirre et al.,
2021; Alonso et al., 2023; Suri et al., 2023).
Anchoveta oil presented 37.57% of PUFAS, among
which DHA (22.6%) and EPA (13.6%) stood out;
these results were similar to those presented by Alonso
et al. (2023). Chestnut and sesame oil are
characterized by high linoleic fatty acid contents
(~42%), this is confirmed by España et al. (2011) and
Teklu et al. (2022), respectively. Olive oil presented a
majority of oleic acid, the main component of
MUFAS. On the other hand, olive oil presented
15.48% PUFAS, mainly composed of linoleic acid (ω-
6), both fatty acid profiles were confirmed by the
reports of Özyurt et al. (2020) and Xiang et al. (2017),
respectively.
Regarding the chemical characteristics of the oils, the
PV in all cases were less than 15 meqO2/kg,
recommended by the Codex Alimentarius (2015). The
VA values for the various oils are similar to those
presented by: Özkan and Özcan (2016) for olive oil
(0.11 mg KOH/g); Alonso et al. (2023) for anchoveta
oil (0.43 mg KOH/g); Rodriguez et al. (2022) for sacha
inchi oil (1. 1 mg KOH/g); Tańska et al. (2016) for
Flaxseed oil (0.5 mg KOH/g); Rodriguez et al. (2020)
for chia oil (0.43 mg KOH/g) and sesame (0.61 mg
KOH/g). The p-AV of the vegetable oils were lower
than the values of the anchoveta oil, this is explained


 



 


pág. 50
Artículo científico
Volumen 6, Número 2, julio - diciembre, 2023
Recibido: 19-07-2023, Aceptado: 11-10-2023
https://doi.org/10.46908/tayacaja.v6i2.213
by the greater deterioration of the unsaturated acids
(ɷ-3) specific to anchoveta oil, which generates
chemical compounds of late stages in a lower
proportion than the vegetable oils presented in this
study. As a consequence, the TotOx value of
anchoveta oil was higher compared to the other
samples, presenting statistically significant
differences (p < 0,05).
Oxidative stability index and shell life
The OSI of vegetable oils and anchoveta oil were
compared at a temperature of 100°C (Table 2),
because at this temperature all oils presented OSI
results within the range of analysis. The analysis
temperatures depend on the chemical nature of the
oils, which translates into oxidation resistance time
(Rodríguez et al., 2020). According to the fatty acid
profile, oils with higher PUFAS content presented
lower OSI values than those with higher SFA values,
in the order of: olive > chestnut > sesame> flaxseed >
chia > sacha inchi > anchovy.
Table 1
Physicochemical characteristics of Peruvian oils
Profile
Oils
Olive
Chestnut
Sesame
Sacha inchi
Anchovy
C14:0
0.048 ±
0.006b
nd
nd
nd
8.877 ±
0.076a
C16:0
15.980 ±
0.028b
12.918 ±
0.006c
11.083±
0.091d
3.933 ±
0.125g
20.453 ±
0.066a
C16:1
nd
2.723 ±
0.032b
nd
nd
9.818 ±
0.026a
C18:0
1.950 ±
0.024f
nd
6.253 ±
0.111a
2.528 ±
0.056e
4.810 ±
0.054c
C18:1
66.100 ±
0.050a
34.868 ±
0.327c
38.653 ±
0.129b
8.893 ±
0.051f
15.717 ±
0.189e
C18:2 (ω-6)
15.467 ±
0.047d
42.668 ±
0.115a
42.649 ±
0.119a
36.552 ±
0.073b
1.277 ±
0.125f
C18:3 (ω-
3)
0.013 ±
0.005e
6.533 ±
0.096d
0.315 ±
0.018e
48.085 ±
0.084c
0.125 ±
0.019e
C20:0
0.140 ±
0.014d
0.233 ±
0.010c
0.335 ±
0.011b
nd
1.797 ±
0.037a
C20:5 (ω-
3, EPA)
nd
nd
nd
nd
22.490 ±
0.029
C22:6 (ω-
3, DHA)
nd
nd
nd
nd
13.687 ±
0.119
SFA
18.370 ±
0.057b
13.151 ±
0.015d
17.671 ±
0.031c
6.462 ±
0.070g
35.937 ±
0.078a
MUFAS
66.100 ±
0.041a
37.591 ±
0.235c
38.653 ±
0.105b
8.893 ±
0.042f
25.535 ±
0.172d
PUFAS
15.480 ±
0.050g
49.201±
0.203d
42.963 ±
0.115e
84.636 ±
0.061a
37.578 ±
0.227f
ɷ-6
15.467 ±
0.047d
42.688 ±
0.115a
42.649 ±
0.119a
36.552 ±
0.073b
1.277 ±
0.125f
ɷ-3
0.013 ±
0.005f
6.533 ±
0.096e
0.315 ±
0.018f
48.085 ±
0.084c
36.302 ±
0.108d
ɷ-3/ɷ-6
0.001 ±
0.000c
0.153 ±
0.002c
0.007 ±
0.000c
1.316 ±
0.004bc
28.688 ±
2.593a
Acidity
(%)
0.910 ±
0.008b
0.900 ±
0.022b
0.350 ±
0.041e
1.083 ±
0.025a
0.927 ±
0.005b
Iodine
(mg I2/g)
89.783 ±
0.883f
160.833 ±
1.008d
123.167 ±
1.778e
191.867 ±
1.915a
178.327 ±
1.605c
PV (meq
O2/kg)
1.840 ±
0.008c
0.487 ±
0.009f
1.223 ±
0.021e
2.023 ±
0.012b
4.870 ±
0.008a
p-AV
1.110 ±
0.008b
1.140 ±
0.014b
1.340 ±
0.014b
1.410 ±
0.008b
13.067 ±
1.144a
TotOx
4.790 ±
0.132bc
2.113 ±
0.029d
3.787 ±
0.053c
5.457 ±
0.021b
22.807 ±
1.156a
*Equal letters in the same row do not show significant difference (p<0.05). nd: not detected.
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https://doi.org/10.46908/tayacaja.v6i2.213
Olive, chestnut and sesame oils were the only ones that
did not show a significant difference (p<0,05) at
100°C; however, as the temperature increased, it
became evident that chestnut oil presented a higher
resistance to oxidation (higher OSI) than olive and
sesame oils. Table 3, shows the shelf life of the oils.
As expected, the highest projection values
corresponded to olive oil, approximately one year,
while chestnut and sesame oil presented less than half
a year, with no significant difference (p<0,05).
The Q10 values obeyed the principle of doubling of
the reaction rate for each 10°c increase in temperature.
Table 2
Oxidative stability index (OSI) of oils
Oils
Temperature (°C)
60
70
80
90
100
110
120
130
Oliva
-
-
-
-
18.626±0.089a
7.529±0.021
3.528±0.016
1.527±0.019
Chestnut
-
-
-
-
18.700±0.283a
9.777±0.020
4.400±0.041
2.207±0.025
Sesame
-
-
-
-
18.333±0.125a
9.450±0.041
3.747±0.041
1.700±0.014
Flaxseed
-
-
-
12.767±0.034
6.220±0.022b
2.567±0.009
1.050±0.040
-
Chia
-
-
-
6.187±0.025
3.027±0.021d
1.500±0.008
0.797±0.021
-
Sacha inchi
-
-
7.480±0.016
3.533±0.025
1.567±0.012c
0.523±0.021
-
-
Anchovy
5.333±0.125
2.400±0.082
1.167±0.047
0.513±0.009
0.317±0.012e
-
-
-
*Equal letters in the same row do not show significant difference (p<0,05), OSI in horas (h).
Autooxidation kinetic parameters
The kinetic parameters of the oils were presented in
Table 4, showing the high susceptibility of anchovy oil
to oxidation compared to vegetable oils, as can be seen
in the Ea value, which indicates the behavior of the
autooxidation reaction. High Ea values are due to a
higher content of saturated fatty acids in the oil matrix;
on the contrary, unsaturated fatty acids mostly reduce
Ea values (Adhvaryu et al., 2000).
Anchoveta oil presented the lowest Ea value,
compared to vegetable oils, this was lower than 82.84-
96.97 kJ/mol, presented by Yang & Chiang (2017).
Olive oil presented the highest Ea value (103.27
kJ/mol), this was similar to the 101.87 kJ/mol, found
by Alonso et al. (2023).
In the case of sacha inchi oil, the value was lower
(115.13 kJ/mol) presented by Rodríguez et al. (2022).
The enthalpy of all samples was endothermic in
nature, as the values were positive (∆H^(++) > 0)
(Farhoosh & Hoseini-Yazdi, 2013). Regarding the
entropy, negative values (∆S^(++)< 0) were obtained
in all samples, this suggests that the activated
complexes are more ordered than their reactants.
In other words, the activated complex will have a
slower oxidation reaction rate (Rodríguez et al., 2020).
Regarding the Q10 values for all oils ranged from
1.982 - 2.306, these values indicate that for every 10
°C increase in temperature the reaction rate doubles
(Redondo-Cuevas et al., 2018).
Table 3
Shelf life (
〖
OSI
〗
_25) and Q_10 of oils
Oils
(meses)
Olive
-0.035 ± 0.000
4.846 ± 0.025
0.995 ± 0.000
12.366 ± 0.555a
2.306 ± 0.007b
Chestnut
-0.031 ± 0.000
4.413 ± 0.041
0.998 ± 0.000
5.943 ± 0.441b
2.043 ± 0.004b
Sesame
-0.035 ± 0.001
4.440 ± 0.101
0.998 ± 0.030
5.170 ± 0.936b
2.228 ± 0.015a
Flaxseed
-0.036 ± 0.000
4.405 ± 0.047
0.991 ± 0.000
4.351 ± 0.344c
2.308 ± 0.281b
Sacha inchi
-0.041 ± 0.001
4.264 ± 0.170
0.998 ± 0.000
2.498 ± 0.072d
2.457 ± 0.044b
Chia
-0.029 ± 0.000
3.462 ± 0.032
0.999 ± 0.000
0.727 ± 0.040e
1.982 ± 0.031b
Anchovy
-0.034 ± 0.000
2.743 ± 0.049
0.999 ± 0.010
0.111 ± 0.009f
2.186 ± 0.064b
*Equal letters in the same row do not show significant difference (p<0,05)
pág. 52
Artículo científico
Volumen 6, Número 2, julio - diciembre, 2023
Recibido: 19-07-2023, Aceptado: 11-10-2023
https://doi.org/10.46908/tayacaja.v6i2.213
Table 4
Kinetic parameters of oils
Oils
Ea
(J/mol K)
(kJ/mol)
(kJ/mol)
(kJ/mol)
Olive
103.271± 0.677a
100.067 ± 0.677a
2.808 ± 1.777b
- 98.950 ± 1.384a
Chestnut
90.039 ± 1.025b
86.832 ± 1.025b
38.723 ± 2.646a
- 71.421 ± 2.078b
Sesame
100.736 ± 2.998a
97.531 ± 2.998a
10.132 ± 6.955b
- 93.500 ± 6.153a
Flaxseed
99.262 ± 1.316a
96.140 ±1.316a
4.008 ±3.025b
- 94.545 ± 2.737a
Sacha inchi
98.607 ± 1.385a
95.569 ± 1.385a
6.835 ± 3.855b
- 92.848 ± 0.149a
Chia
81.291 ± 0.858c
78.166 ± 0.858c
46.425 ± 2.309a
- 59.689 ± 1.777c
Anchovy
77.776 ± 1.315c
74.900 ± 1.315c
35.022 ± 3.698a
- 60.961 ± 2.784c
*Equal letters in the same row do not show significant difference (p<0,05).
CONCLUSIONS
Various foods native to Peru are known for their
nutritional and bioactive properties. Oils derived from
vegetable and marine sources are rich in omegas (ω-3
and ω-6), which are important for human health.
However, the deterioration of the raw materials
studied in this work presents substantial differences
due to their chemical structure. The use of the rancimat
equipment allowed comparing the oxidation resistance
times or oxidative stability indexes (OSI) under
accelerated deterioration conditions, determining that
the order of deterioration of the oils were: olive <
chestnut < sesame < sacha inchi < flaxseed < chia <
anchoveta. The oxidation kinetics allowed
characterizing thermodynamic properties (k, Ea, ∆H,
∆S and Q10), which would help in quality control and
development of new products.
ACKNOWLEDGMENTS
This work was carried out at the facilities of the
Instituto de Investigación Agroindustrial (IITA) of the
Universidad Nacional del Santa (UNS). We are
grateful to the office of the Vice Rectorate of Research
(VRIN) - UNS, for the facilities in sending this
manuscript.
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