107

1 INTRODUCTION

The quality of food is the result of such points as its

nutritional, health or sensory properties. These

qualities depend, not only on the original composition

of raw materials used to its production, but also on

preserving safety and proper method of conducting

all processes that foodstuffs are subjected to during

their lifecycle.

In transport, foodstuff undergo many

transformations, due to physical, biochemical and

microbiological factors. In reference to edible oils, this

could result in inducing the reactions such as

oxidation, hydrolysis, polymerization and various

types of physical transformations, which reduce oils

utility for producers and consumers. According to

that, it is important to broaden knowledge, which

enables to avoid harmful effects, which could occur in

discussed type of liquid cargo, for example during

maritime transport.

Available literature, subjected to this issue, usually

describes the transformations to which edible fats

may be exposed, but it rarely presents possible

methods, applicable in practice, for reducing negative

changes and their dynamics.

The paper focuses on vegetable oils market, on

characteristic of rapeseed oil, on changes to which it is

subjected during storage (also in maritime transport)

and on conditions and methods of its protection from

external factors. Assumption of the study was that

The Dynamic of Oxidative Changes in Rapeseed Oil

uring Maritime Transport Determined by Storage

onditions

A. Ocieczek

, A. Kaizer & A. Zischke

Gdynia Maritime University, Gdynia, Poland

ABSTRACT: In order to provide quality and safety of liquid cargo carried by sea, it is necessary to obey the

rules of its protection. During maritime transport edible oils are prone to detrimental influence of many

external factors such as supply of oxygen, of water, of metal ions and of pollution, as well as changes of

temperature and mixing caused by ship movement. Due to them, they could undergo oxidation reactions,

hydrolysis, polymerization and various types of physical transformation. On account of them the deterioration

of nutritional, health and sensory qualities of fat could occur.

The aim of the study was the assessment of the dynamic of changes with oxidative character (peroxide value

and TBA index) which could appear in edible oils depending on their storage conditions.

The analysis, which lasted 12 weeks, concerns rapeseed oil. Oxidative changes were registered every two week.

The storage conditions in the atmospheric air induced danger connected with oxygen presence, whereas

nitrogen blanketing eliminated this risk factor. The assessment also includes the influence of temperature of

storage (indoor temperature 20˚C or refrigeration temperature 4˚C) and mixing of the fats.

The results indicate that nitrogen blanketing, lowering the temperature and eliminating the mixing during

storage of oil have highly positive impact on reduction of oxidative changes in fats.

http://www.transnav.eu

the

International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 14

Number 1

March 2020

DOI:

10.12716/1001.14.01.12

108

blanketing the rapeseed oil with nitrogen is the most

effective action, which leads to reduction of dynamics

of its deterioration. In order to verify underlying

presumption, the changes of peroxide value and TBA

index were examined and then their dynamics in

varied ambient conditions were compared.

2 MARKET AND COMMODITY

CHARACTERISTICS OF EDIBLE OILS

The production as well as consumption of oils have

been constantly increasing for many years. The

foundation of their global production are: oil palm,

soybean, rapeseed, sunflower, cotton, peanut, coconut

and olive oil [Wroniak and Ratusz, 2014]. The basic of

Polish oil industry are oils such as: rapeseed oil,

sunflower oil, soybean oil, peanut oil and mixed oils

(for example rapeseed oil with sunflower oil or

soybean oil) [Palich at al. 2006]. In 2016, 602 000 tons

of vegetable oils (worth EUR 516 million) were

exported from Poland. 68% of which was rapeseed

oil. In the first half of 2017, around 492 000 tons of

crude rapeseed oil were produced in Poland. About

392 000 tons of which were refined [Oil Express,

2017].

At the same time, 720 000 tons of vegetable oils

were imported to Poland (worth EUR 702 million).

81 000 tons of that was rapeseed oil [Oil Express,

2107]. The balance of import and export of vegetable

oils within 8 years between 2009 and 2016 has been

presented in Figure 1.

Figure 1. Foreign trade of vegetable oils in 2009-2016 [Oil

Express, 2017]

Rapeseed oil takes third place in the world

production of oils. Its main producers are countries

such as: Canada, China, India and in Europe:

Germany, France, Great Britain, Poland, Russia and

Ukraine [Wroniak and Ratusz, 2014]. This oil is

widely used as edible oil. It is characterized by a high

smoke point and it could be applicable also in other

sectors, not only in the food industry, for example in

the production of biofuels.

The basic ingredient of edible fats are

triacylglycerols. They make up 99% of the

composition of refined oils. These are esters of

glycerol and fatty acids. At a temperature of 15°C the

density of vegetable oils is between 910 and 970 kg/m

and it decreases linearly when temperature increases.

The coefficient of thermal changes of density is

0,67kg/m

for 1°C [Wiktor, 1994]. All vegetable oils

are combustible. However, due to the fact that they

are characterized by high flash point, they are not

classified as hazardous materials [Leśmian-Kordas

and Pilawski, 1992].

Rapeseed oil is composed mainly of monoenoic

and polyenoic fatty acids, which influence its utility

properties. According to principles of human

nutrition, rapeseed oil is characterized by relevant

participation of acids ω-6 to ω-3 (ca. 2:1), which

makes it really valuable foodstuff. Acids ω-3 are

especially important in relation to dietetics because

they improve proper functioning of the human

nervous and immune system, as well as brain activity.

They could also reduce the risk of cardiovascular

diseases and diabetes, which are civilization diseases

in developed countries. Rapeseed oil, in comparison

to other oils available in market, contains also the

greater number of sterols, including brassicasterol.

Food durability was defined by the Institute of

Food Science and Technology and is understood as

the time when the foodstuff, properly stored, is safe

and maintains its organoleptic, physical, chemical and

microbiological qualities at the assumed level and

also keeps declared nutrition properties [Samotyja,

2016]. Food durability is an important factor of food

quality and determines its availability.

Edible oils during storage or transport can

undergo many different chemical reactions [Kłopotek

et al. 2017]. Overall transformations which occur in

them, are referred as rancidity. It results in change of

chemical composition of oil, which could lead to the

deterioration of the product, to the change of its

sensory attributes or to the loss of its healthing

properties [Nierzwicki 2013]. Products of these

reactions are usually free fatty acids, oxides and

peroxides, aldehydes and ketones and products of

their polymerization as well. Some of emerging

chemicals could even have harmful effects on the

human body. Aldehydes, ketones and acids are

classified as biologically active substances. Their

actions could lead to damage of cell membranes and

intercellular structure and also to reduction of

enzyme activity. These could also cause cytotoxic or

mutagenic effect. [Cichosz and Czeczot, 2011].

Fatty acids, especially unsaturated, present in

edible oils, are prone to oxidation reactions. As a

result of these reactions hydroperoxides are formed.

The growth of hydroperoxides content in composition

of oil, leads to increase of peroxide value (PV) and

causes reduction of iodine value (IV) [Czechowska-

Liszka, 2012]. Process of oils oxidation is stimulated

by many environmental factors such as temperature,

oxygen presence, occurrence of catalytic metal ions

(for example: copper, cobalt, iron, chromium), pH of

surrounding environment, storage time and access to

light [Palich, 2000], especially ultraviolet radiation

and radiation of blue light [Leśmian-Kordas and

Pilawski, 1992].

Another type of transformation, which could occur

in the oil composition, is hydrolysis. It leads to the

breakdown of triacylglycerols and to the release of

free fatty acids, monoacylglycerols, diacylglycerols

and glycerol [Czechowska-Liszka, 2012]. This results

in growth of fat acidity and causes the increase of acid

value (AV). Sensory changes of fats, which are

109

capable of undergoing hydrolytic transformations, are

mostly conditioned by appearance of short-chain fatty

acids [Palich, 2000]. Acids released as a result of

hydrolysis are impermanent chemicals compounds.

Therefore, they could also generate an emergence of

many secondary products, which could cause a

significant deterioration of flavor and odor of

product. According to that, it is very important to

preserve oil properly from humidity during storage

and transport (especially maritime transport).

If it is not enough, another process which is typical

for fats, is polymerization. This reaction occurs as an

effect of long lasting or repeating heating. As a result

of that, oligomers, dimers or cyclic compounds

emerge. Presence of this chemicals, contributes to

reduction of the nutritional value, digestibility and

bioavailability of fat [Czechowska-Liszka, 2012].

Products of that reaction may also cause change of

flavor and color of fat. They could also increase its

viscosity [Leśmian-Kordas and Pilawski, 1992].

On the other hand, low temperature could lead to

stratification of fat and to precipitation of some

components of oils, for example stearin [Wiktor,

1994]. Therefore, it is essential to avoid achieving

temperature close to pour point of oil, during its

storage. First of all, supercooling could result in

transformation of high melting compounds to solid

state, which is manifest as turbidity. These kinds of

reactions usually occur in the short time and narrow

range of temperature. Due to that fact, it is relevant to

adjust storage and transport conditions to

physicochemical characteristics of the oil.

Edible fats qualify as perishable products. They

could undergo rancidity as an effect of different

external factors such as admission of light and oxygen

or high temperature. Therefore, they require to be

kept in suitable conditions to avoid their premature

deterioration. Spaces which are devoted to storage

and transport of edible oils, should be clean, dry, and

dark, or illuminated with diffused light [Palich, 2000;

Wroniak and Ratusz, 2014]. In these areas, relative

humidity of the ambient air should vary from 75% to

85%. It is worth noticing that decreasing the

temperature allows to reduce the speed of chemical

reactions, the development of microorganisms and

the occurrence of biological changes [Nierzwicki,

2013]. Due to that fact, temperature in the discussed

areas, should range from +4 to +6°C. Such way of

storage enables to preserve the oil durability for 6

months, while maintaining the temperature not

exceeding 15°C shortens this period to 3 months.

The most suitable containers for storing edible oils

are narrow, tall, vertical tanks with a circular cross

section. They should have a conical or sloped bottom

to allow self-flow [Berger, 1985].

According to the fact that main factor which

influence the oxidation of fats is presence of oxygen,

oils could be preserved by using modified

atmosphere packing (MAP), and taking advantage of

nitrogen [Wroniak and Ratusz, 2014]. It enables to

maintain their nutritional and organoleptic quality,

and also allows to extend durability, preserve taste

and consistency of product, and protect it from

mechanical damage. Even when liquid oils are

purged with inert gas only once, the oxygen could be

flushed out and its content in the product may be

reduced by as much as 80-90%. It is possible to

conduct inertisation while storing the oil in the tanks,

as well as during bottling it [Airliquide, 2017].

When oil is being delivered, means of transport act

as temporary warehouses. They must protect the

product against the adverse effects of external factors.

It is also important to properly arrange and fasten

cargo that could be exposed to moisture and lateral

pressures during sea transport during the sea

transport [Czarniecka-Skubina, 2010].

3 BLANKETING OF OILS IN INERT

ATMOSPHERE

The main factor decreasing the final quality of oil is

the oxygen content, which was dissolved in fat

[Wroniak et al., 2015]. In order to minimize the effect

of this factor, inert gases such as carbon dioxide (CO

and nitrogen (N

2) can be used while storing.

When temperature is decreasing, the solubility of

2 in fats and water increases.

2 has bacteriostatic properties, and may also be

an inhibitor for some enzymes. It is able to lower the

pH of food by forming carbonic acid in an aqueous

environment, and its gas fraction can inhibit the

growth of microorganisms.

2 doesn’t have bacteriostatic properties and is

poorly soluble in fats and water. However, its usage

in oil storage, gives the opportunity to create an

anaerobic environment in the packaging, which limits

oxidation processes. The removal of air above the oil

also reduces the amount of water contained in it,

which may have a beneficial effect on the inhibition of

the hydrolysis process and on the changes in the

sensory characteristics of fat which are associated

with it.

Accordingly, the usage of inert gases could be an

effective, as well as safe, from a health point of view,

method to reduce unfavorable changes occurring in

oils. Although better results were achieved with

carbon dioxide, nitrogen is more often used, for

economic reasons [Jędrzejkiewicz and Krygier, 2008].

During storage and transport of fats, deterioration

of their quality may occur due to long-term contact

with oxygen from the air. The time necessary for oil

transport depends on the type of oil (its origin) and

the conveyance route. This could take from several

weeks to several months for cargo to reach its

destination [Takashina et al. 1994]. Therefore, ships

and oil storage tanks which are high quality, or which

are devoted to long term storage, should have

facilities for bubbling and covering the load with an

inert gas. Moreover, filling the stream of pumped oil

with pressurized nitrogen, may be an effective way to

protect refined fats [Berger, 1985; FAO/WHO, 2015].

For this purpose, nitrogen with a concentration not

less than 99.5% is used [Takashina et al. 1994] because

too low purity of nitrogen, could lead to problems

with the stability of vegetable oils.

Changes which may occur in fats during storage or

transport could be characterized by different quality

indicators. First of these are the peroxide value and

the TBA index. Their changes, associated with the

110

storage of edible oil under different conditions, have

been experimentally determined and described in the

empirical part of this work. In addition, there are also

the acid number, saponification number and iodine

number, which could be indicated or Kreis test which

could be conducted [Stasiuk and Przybyłowski 2008].

4 AIM AND METHODS OF RESEARCH

The aim of the study was to define the dynamic of

oxidative changes, which could appear in edible oils

depending on their storage or transport conditions.

The object of research was refined rapeseed oil. The

study was a multifactorial analysis. Research focused

on factors such as: 1) presence of oxygen or nitrogen

in the sample tube; (2) oil storage temperature; (3)

mixing of the sample; (4) time of oil storage. It was

subjected to define the influence that these factors

have on the changes of the peroxide value and the

TBA index during 12 weeks of storage.

A zero test and four repetitions were carried out

for each of the 6 prepared samples - after 3, 6, 9 and

12 weeks, and their peroxide number and TBA index

were indicated.

Six samples were taken from these same bottle of

refined rapeseed oil. Each of them was placed in a

previously prepared utensil, which enabled to fill it

with air or nitrogen, as shown in Figure 2.

Figure 2. Scheme of the utensil for sample storage

The utensil was filled out with such volume of

sample that after placing it in a horizontal position its

content did not leak out through the taps. Afterwards,

when inlet and outlet were opened, air or nitrogen,

depending on the sample, was blown through the

utensil, in order to eliminate the presence of other

gases. The subsequent step was to fill the utensil

tightly with the eligible gas.

The utensils filled with air or nitrogen were

divided into 3 groups:

− stored motionless, in a refrigerator, at temperature

4°C

− stored motionless, at room temperature 20°C,

− stored at room temperature 20°C, shaken at

irregular intervals.

The special construction of the outlet taps allowed

to take the sample of oil after putting the utensil in a

vertical position. Therefore, it prevented the leak of

the gas contained in the utensil or its mixing with

outside air.

In order to imitate the conditions prevailing in the

container, during the transport of oil, the utensils

were protected from sunlight using aluminum foil.

At the same time, the sample was taken, to

indicate the designation for the zero test on it.

4.1 Determination of peroxide value

Peroxides are products of fat oxidation reactions. The

peroxide value (PV) defines the amount of substance

which oxidize potassium iodide to iodine contained

in one kilogram of fat. It is also connected with

creation of epihydryne aldehyde [PN-EN ISO

3960:2012].

4.2 Determination of TBA index

As a result of the aldehyde rancidity process, a

characteristic product - malondialdehyde - may be

formed. In order to detect it, the so-called TBA index

could be used [Stasiuk and Przybyłowski, 2008]. This

index is determined by thiobarbituric test, which

enables to follow the oxidative processes occurring in

fat.

5 OVERVIEW AND DISCUSSION OF RESULTS

The peroxide values of rapeseed oil recorded during

storage under the conditions of the experiment, were

primary data for approximation of parameters of

linear regression equations. They were subjected to

describe the dynamics of changes occurring during 12

weeks of storage under different conditions (Tab. 1).

Table 1 also shows the values of the coefficient of

determination R

, which is the proportion of the

variance in the dependent variable, that is predictable

from the independent variable.

Table 1. Linear regression equations describing the dynamic

of changes of peroxide values during 12 weeks of storage

under different conditions together with values of

coefficient of determination R

_______________________________________________

Storage type Regression Coefficient

equation R

_______________________________________________

Nitrogen, motionless, y=1.7771x-2.2517 0.8456

room temperature

Nitrogen, shaken, y=0.3455x+0.6741 0.6333

room temperature

Nitrogent, motionless, y=0.1330x+0.6240 0.6920

refrigerator

Air, motionless, room y=7.3978x-9.5005 0.9636

temperature

Air, shaken, room y=13.379x-11.922 0.9837

temperature

Air, motionless, y=2.4849x-3.4246 0.7577

refrigerator

_______________________________________________

Coefficient R

(square of the correlation coefficient between

the explained variables and explanatory variables)

Comparison of the course of curves describing

changes in the peroxide value, enables to state that

111

storage conditions have significant influence on

variation in the dynamics of changes of peroxide

value of rapeseed oil during its 12 weeks incubation

in experimental conditions.

Storage of rapeseed oil under an atmosphere of air,

which contains about 21% of oxygen, caused a

considerable increase in the peroxide value in all

variants of the experiment. This is indicated by the

high values of the regression coefficient (from 2.4849

to 13.3379), which defines how much the value of the

dependent variable (PV) increased, in case of the

increase of the independent variable (time) by one

unit. Comparison of the values of regression

coefficients for the temperature 4°C and 20°C allows

to conclude that the use of low storage temperature

(4°C) and at the same time limiting the oxygen access

by eliminating shaking of the oil during storage, had

contributed to reduction of the oxidation of fat. This

reflects in the persistence of relatively low peroxide

values during storage. Increase of the storage

temperature (20°C), whilst maintaining limited

oxygen access, by eliminating shaking of oil during

storage, led to a nearly three-fold increase in the

regression coefficient, which resulted from the rise in

dynamics of peroxides formation. On the other hand,

the appearance of an additional exposure factor, in

the form of shaking oil during its storage, which

results in an increase of the extend of aeration, and

thus oxygenation, contributed to an almost 5.5-fold

increase of the regression coefficient.

The elimination of the atmosphere, which has an

oxidative characteristics, improved the storage

stability of rapeseed oil. In reliance to undoubted low

values of the regression coefficient of the linear

function (from 0.1330 to 1.7771) describing changes in

time of 12 weeks of incubation, storage of rapeseed oil

under the nitrogen atmosphere significantly reduced

the increase of peroxide value in all variants of the

experiment. It is worth noticing that due to storage at

low temperature (4°C) and elimination of oil mixing

during storage, the fat oxidation occurred at

extremely low dynamics (0.1330). What is more, the

high protective efficiency of nitrogen, in comparison

to air, which is the source of oxygen, is demonstrated

also by the comparison of the values of regression

coefficients, which describe the changes occurring

under conditions of increased temperature and

increased temperature combined with mixing. Higher

value of the regression coefficient of the function

describing changes of the peroxide value over time,

obtained when oil was stored at increased

temperature with restriction of mixing (1.7771) in

comparison to regression coefficient describing

changes of the peroxide value over time determined

for the experimental variant assuming oil storage at

increased temperature with exposure to mixing

(0.3455), undoubtedly indicates that there had to be

leakage during the test. As a result of this, oxygen got

to the utensil together with the air, which led to a

significant acceleration of the peroxide value growth

rate. According to that, this value should be

considered as increased in a way which is not related

to the assumptions of the experiment. At the same

time, it is worth emphasizing that very low value of

regression coefficient (0.3455) referring to changes of

the peroxide value during storage of rapeseed oil

under nitrogen atmosphere, at increased temperature

and under conditions of its mixing (extreme

conditions), is an evidence of stability of rapeseed oil

in terms of changes in oxidation, conditioned by the

protective function of nitrogen. In reliance to that, it

could be assumed that if there had not been any

leakage of utensil during oil storage under nitrogen

atmosphere, at room temperature, without exposing it

to mixing, the regression coefficient of the linear

function would have been lower than 0.3455.

Oils kept in utensils filled with air featured higher

dynamics of changes of peroxide value than oils

stored in nitrogen. Regardless of the composition of

gas atmosphere in which oils are stored, keeping

them at low temperature (cooling), positively reduces

the dynamics of changes of their peroxide values.

Cyclical mixing of oils stored in the air-filled utensils,

resulted in a higher dynamics of peroxide number

changes, in comparison to storage under conditions

which avoid mixing of liquid. For samples filled with

nitrogen, this regularity occurred only during the first

six weeks of sample storage. The maximum peroxide

value, specified by the standard on the level of 5 [mEq

2/kg], has not been exceeded in case of oil, which

was:

− stored in nitrogen, motionless, at room

temperature – during the first nine weeks of

storage,

− stored in nitrogen, shaken, at room temperature –

during the first twelve weeks of storage,

− stored in nitrogen, motionless, in a refrigerator –

during the first twelve weeks of storage,

− stored in air, motionless, at room temperature –

during the first three weeks of storage,

− stored in air, motionless, in a refrigerator – during

the first nine weeks of storage.

In case of oil stored in air, at room temperature

and shaken, the defined peroxide value has

significantly exceeded appointed value after the first 3

weeks of storage (13.13596 mEq O

2/kg).

Comparison of the course of curves describing

changes of the absorbance value of a rapeseed oil

distillate over time (TBA test) using the analytical

method (Tab. 2.), leads to the conclusion that storage

conditions have the significant influence on variation

in the dynamics of its changes during 12 weeks

incubation in experimental circumstances.

Table 2. Linear regression equations describing the dynamic

of changes of the absorbance value of a rapeseed oil

distillate during 12 weeks of storage under different

conditions together with values of coefficient of

determination R

_______________________________________________

Storage type Regression Coefficient

equation R

_______________________________________________

Nitrogen, motionless, y=0.1163x-0.153 0.8068

room temperature

Nitrogen, shaken, room y=0.0476x+0.0396 0.919

temperature

Nitrogent, motionless, y=0.0081x+0.2970 0.036

refrigerator

Air, motionless, room y=0.1535x-0.1727 0.8792

temperature

Air, shaken, room y=0.1752x+0.0935 0.9225

temperature

Air, motionless, y=0.0621x+0.0434 0.9487

refrigerator

_______________________________________________

112

Coefficient R

(square of the correlation coefficient between

the explained variables and explanatory variables)

In case of storing rapeseed oil in the atmosphere of

air, the increase in the radiation beam absorbance

value assigned to distillate was observed in all

variants of the experiment. This is indicated by values

of the regression coefficient ranging from 0.0621 to

0.1752. Keeping the oil at low temperature (4°C) with

elimination of oil mixing, allowed to reduce the

absorbance value. The increase of the storage

temperature (20°C), whilst maintaining limited

oxygen access, by eliminating shaking of oil during

storage, led to a nearly 2.5-fold increase in the

regression coefficient. This regularity resulted from

the increase of dynamics of formation of

malondialdehyde, which is responsible for

absorbance. On the other hand, the appearance of an

additional exposure factor, in the form of shaking oil

during its storage, which results in an increase of the

extend of aeration, and thus oxygenation, contributed

to an almost threefold increase of the regression

coefficient.

Taking advantage of a reducing atmosphere, in the

form of nitrogen, improved the storage stability of

rapeseed oil. Keeping rapeseed oil under a nitrogen

atmosphere, reduced the increase in malondialdehyde

concentration, in all variants of the experiment, which

is indicated by lower, in comparison to the air

atmosphere, values of the regression coefficient (from

0.0081 to 0.1163). The low temperature of storage

(4°C) and the elimination of oil mixing during

storage, resulted in extremely low dynamics of fat

rancidity (0.0081). The effectiveness of the nitrogen as

protective gas, in comparison to air, which is the

source of oxygen, has been demonstrated by

comparing the values of regression coefficients,

describing the changes occurring under conditions of

increased temperature and increased temperature

combined with mixing. Higher value of the regression

coefficient of the function, describing changes of the

absorbance value of the tested oil samples during

storage, obtained when oil was kept at increased

temperature with restriction of mixing (0.1663), in

comparison to the regression coefficient describing

changes of the absorbance value over time,

determined for an experimental variant, assuming oil

storage at increased temperature with exposure to

mixing (0.0476), once again indicates that there had to

be leakage during the test. As a result of this, oxygen

got to the utensil together with the air, which led to a

significant acceleration of malondialdehyde

formation. According to that, this value should be

considered as increased in a way which is not related

to the assumptions of the experiment. At the same

time, it is worth emphasizing that very low value of

regression coefficient (0.0476), referring to changes of

malondialdehyde concentration during storage of

rapeseed oil under nitrogen atmosphere, at increased

temperature and under conditions of its mixing

(extreme conditions), is an evidence of stability of

rapeseed oil in terms of being prone to rancidity,

conditioned by the protective function of nitrogen. In

reliance to that, it could be assumed that if there had

not been any leakage of utensil during oil storage

under nitrogen atmosphere, at room temperature,

without exposing it to mixing, the regression

coefficient of the linear function would have been

lower than 0.0476.

In case of oil kept in nitrogen, ones which were

stored motionless at room temperature, and shaken at

room temperature, and in case of oil kept in air, ones

which were stored motionless at room temperature,

and motionless in refrigerator, have TBA index

relatively constant during the first 6 weeks of the

study. A comparatively large increase in the TBA

index was observed in these samples after 12 weeks.

Weighing all above considerations, the following

conclusions could be made:

− blanketing the vegetable oil with nitrogen

contributes to a significant slowdown of fat

oxidation reaction, in comparison to oil stored in

the air, at the same time;

− decreasing the storage temperature of vegetable oil

leads to the reduction of its oxidation process;

− shaking the oil during keeping it in the air, at room

temperature, has significant influence on

acceleration of its oxidation process, in comparison

to oil stored motionless. Lack of parallel principle

for oil stored in nitrogen, could result from

probable leakage which occurred after 6 weeks

(sample stored in nitrogen, motionless, at room

temperature), and which could contribute to

higher peroxide value and higher TBA index;

− in case of oil stored in air, only keeping it

motionless, in refrigerator enables to obtain

comparatively low degree of oxidative

deterioration, in comparison to oil stored in

nitrogen.

6 CONCLUSIONS

Edible oils are exposed to many external factors

during maritime transport. This could lead to

deterioration of their nutritional and sensory quality,

as well as affect their safety for consumer health. In

order to avoid the adverse effects of these changes,

the appropriate rules for transport of this specific

liquid cargo should be obey, as well as proper

methods of its protection should be applied.

First of all, the preservation of edible oils should

mainly consist of the elimination of oxygen, light,

water and pollution supply, as well as should

possibly restrain its mixing and temperature changes.

The conducted research enables to determine to

what extent the selected factors, applicable in practice,

could favorably extend the time of oxidation stability

of fat during its transport. In reliance to obtained

results, it could be pointed that the storage of

rapeseed oil under the nitrogen atmosphere,

restraining its mixing and decreasing the temperature,

contributes to the reduction of the rate of adverse

changes occurring in this fat. Moreover these results

indicate that blanketing the oil with nitrogen has

highly positive impact on reduction of changes, which

cause deterioration of the edible oils quality.

Last but not the least, the discussed analysis allows

to conclude that there are advantages of high

efficiency of combined methods of liquid cargo

protection.

113

REFERENCES

Berger K. G.: Quality control in storage and transport of

edible oils. JAOCS, Vol. 62, no. 2, 1985.

Cichosz G., Czeczot H.: Stabilność oksydacyjna tłuszczów

jadalnych– konsekwencje zdrowotne. Bromat. Chem.

Toksykol. XLIV, 2011, str. 50–60.

Czarniecka-Skubina E.: Towaroznawstwo spożywcze.

Wydawnictwo Format A-B, Warszawa, 2010, str. 48.

Czechowska-Liszka M.: Badanie i ocena tłuszczów

jadalnych, w: Badanie i ocena jakości produktów

spożywczych, pod red. W. Kędziora. Uniwersytet

Ekonomiczny w Krakowie, Kraków, 2012, str. 195-214.

FAO/WHO: Code of practice for the storage and transport

of edible fats and oils in bulk CAC/RCP 36 – 1987.Codex

Alimentarius International Food Standards, 2015.

Jędrzejkiewicz K., Krygier K., Zastosowanie gazów

inertnych do poprawy stabilności oksydatywnej oleju

rybiego, rzepakowego i ich mieszaniny. Żywność.

Nauka. Technologia. Jakość, 2008, 5 (60), str. 248 – 256.

Kłopotek K., Ocieczek A., Palka A.: Wpływ temperatury

przechowywania na wybrane parametry jakości olejów z

orzechów. Zeszyty Naukowe Akademii Morskiej w

Gdyni, 2017, 99, str. 34 – 47.

Leśmian-Kordas R., Pilawski T.: Towary pochodzenia

roślinnego i zwierzęcego w transporcie morskim.

Wyższa Szkoła Morska w Szczecinie, Szczecin, 1992,

str. 100-113.

Nierzwicki W.: Jakość żywności. Wyższa Szkoła Turystyki i

Hotelarstwa w Gdańsku, Gdańsk, 2013, str. 20-25, 125-

131.

Palich P., Ocieczek A., Pukszta T., Skotnicka M.: Podstawy

technologii i przechowalnictwa żywności: ćwiczenia.

Akademia Morska, Gdynia, 2006, str. 73-88.

Palich P.: Podstawy technologii i przechowalnictwa

żywności. Wyższa Szkoła Morska, Gdynia, 2000, str. 134

– 135.

PN-EN ISO 3960:2012, Oleje i tłuszcze roślinne oraz

zwierzęce. Oznaczanie liczby nadtlenkowej.

Jodometryczne (wizualne) oznaczanie punktu

końcowego.

Polskie Stowarzyszenie Producentów Oleju, Oil Express, nr

72 (II), 2017.

Samotyja U.: Znaczenie badań nad trwałością żywności w

aspekcie zapewnienia jej jakości i bezpieczeństwa

konsumenta. Uniwersytet Ekonomiczny w Poznaniu,

Poznań 2016, str. 11 – 21.

Stasiuk E., Przybyłowski P.: Tłuszcze jadalne, w:

Towaroznawstwo artykułów spożywczych część 1, pod

red. P. Przybyłowskiego. Akademia Morska w Gdyni,

Gdynia, 2008, str. 82 – 94.

Takashina S., Hazama T., Kurooka A., Maruguchi N.,

Hiroshi Iwasa H., Masayoshi Saito M.: Method of

preventing edible oils and fats from deteriorating.

United States Patent numer 5298271, 1994.

Wiktor E.: Ładunki okrętowe. Polskie Towarzystwo

Towaroznawcze Oddział Morski, Sopot, 1994, str. 286-

290.

Wroniak M., Ratusz K.: Oleje jadalne część 2 w: Wybrane

zagadnienia z technologii żywności pochodzenia

roślinnego. SGGW, Warszawa, 2014, str. 169-184.

Wroniak M., Rękas A., Piekarniak I.: Wpływ rodzaju

opakowania i warunków przechowywania na wybrane

cechy jakości oleju rzepakowego tłoczonego na zimno.

Żywność. Nauka. Technologia. Jakość, 2015, 2 (99), str.

62 – 78.

Airliquide-https://przemysl.air-

liquide.pl/sites/industry_pl/files/2017/09/14/zapobiegani

e_utlenianiu_plynnych_

produktow_spozywczych_pl_2017.pdf (accessed:

13.12.17)