Els additius alimentaris són components comuns en els aliments i un bon context d'estudi per a les classes de química. En aquest treball, es descriu una sessió de laboratori per a estudiants de secundària (17-18 anys). Els alumnes van determinar algunes propietats físiques i químiques de quatre additius «desconeguts». Utilitzant els resultats de les proves, els estudiants havien d'esbrinar, entre els deu possibles additius d'una determinada llista, quins eren els quatre additius
analitzats. Els estudiants van treballar en petits grups. Un 26 % dels estudiants (grups) va identificar correctament els quatre additius, un 29 % en va identificar tres i el 45 % en va identificar dos.Food additives are common food components and they should be studied in chemistry classes. This paper describes a lab lesson for high school seniors (17-18 years old). They tested some physical and chemical properties of four
unknown additives. Using the test results the students had to figure out which four of the ten additives from a list given had been tested. The students worked in small groups. All four correct additives were chosen by 26 % of students
(groups), three correct additives by 29 % and two correct additives by 45 % of students

Korolija, Jasminka

Mandic, Ljuba

Marinkovic, Dragan

Matijasevic, Igor

Mladenovic, Ivana

Revistes Catalanes amb Accés Obert

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Food additives in chemistry 
lessons
Els additius alimentaris a les classes de química
Jasminka N. Korolija, Ivana Mladenovic, Ljuba Mandic and Igor Matijasevic / University of Belgrade.
Faculty of Chemistry (Serbia)
Dragan Marinkovic / Jarrow Industries, Inc. (Santa Fe Springs, CA, USA)
abstract
Food additives are common food components and they should be studied in chemistry classes. This paper describes
a lab lesson for high school seniors (17-18 years old). They tested some physical and chemical properties of four
unknown additives. Using the test results the students had to figure out which four of the ten additives from a list
given had been tested. The students worked in small groups. All four correct additives were chosen by 26 % of stu-
dents (groups), three correct additives by 29 % and two correct additives by 45 % of students.
keywords
STS project, food additives, lab work.
resum
Els additius alimentaris són components comuns en els aliments i un bon context d’estudi per a les classes de química.
En aquest treball, es descriu una sessió de laboratori per a estudiants de secundària (17-18 anys). Els alumnes van deter-
minar algunes propietats físiques i químiques de quatre additius «desconeguts». Utilitzant els resultats de les proves, els
estudiants havien d’esbrinar, entre els deu possibles additius d’una determinada llista, quins eren els quatre additius
analitzats. Els estudiants van treballar en petits grups. Un 26 % dels estudiants (grups) va identificar correctament els
quatre additius, un 29 % en va identificar tres i el 45 % en va identificar dos.
paraules clau
Projecte CTS, additius alimentaris, treball pràctic.
Introduction
A choice of content and
teaching approach of a chemistry
curriculum has been studied by
methodologists for decades. 
A traditional approach (Fensham,
1985) selected topics important
for chemistry science, making it
(chemistry) self-serving choice.
The STS (science–technology–
society) project changed the tra-
ditional approach of science
teaching (Aikenhead, 1994). Sci-
ence education is viewed by the
STS project from the point of how
important science is in our socie-
ty and how we can apply science
in everyday life. There is a mutu-
al relationship between science
and society. The STS project does
not view the reason for existence
of scientific curriculums as only
to serve required teaching plans
and as a learning requirement for
students (Yager, 1990).
The STS project considers
mutual interactions between sci-
ence, technology and society
enabling inclusion of numerous
topics. The concept of curriculums,
teaching and learning methods
about the macro-world should
include the maximum number of
examples from everyday life.
In Serbia, even current
chemis try curriculums have
teaching topics which could
incorporate everyday life con-
tents (referred to as STS contents).
Some preliminary research
exploring such contents has been
performed. The following criteria
for contents selection have been
used:
– Up-to-date topics:
a) Health, related to
healthy/unhealthy diet (intake of
foodstuff, energy extraction from
fuel molecules and energy con-
sumption).
b) Food (manufacturing of
food, food quality, world famine).
c) Contemporary diseases
[causes and treatments: anorexia,
bulimia, MS (metabolic syn-
drome), alcoholism, drug abuse,
malignant diseases, etc.].
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d) Paradox chemicals (necessi-
ty vs. danger: food additives, 
metal ions, drugs, fuels, pesticides,
alcohols, polymers).
– Ability to utilize knowledge
acquired in past chemistry and
other science courses and lessons
during STS related lessons.
– Design of various types of
student participation (group or
individual) using various teaching
methods (dialogs, textual me -
thods, experiments).
– Availability of chemicals,
glassware and other labware.
– Ability to organize lab activi-
ties for up to thirty students at a
time.
Selected topics («Preservation
and expiration date of food-
stuffs», «Alcohol and young peo-
ple alcoholism», «Metal ions in
our body», «Antibiotics: chemistry
view», «What chemists have to
say about tobacco and smok-
ing?», «Foodstuffs packaging»,
«Food additives») have been used
in chemistry teaching since 1998-
1999 school year in both middle
and high schools. This prelimi-
nary research should serve as a
foundation for introducing the
STS principles in science teaching
in Serbia (Korolija and Stanišic´,
2009; Korolija et al., 2008a; Koroli-
ja et al., 2008b; Korolija et al.,
2009; Korolija et al., 2012).
Food additives encompass a
wide variety of organic and inor-
ganic substances. A survey of
teaching curriculums and plans
for middle and high schools
showed that food additives have
been mentioned occasionally in
classroom studies of certain
chemical compounds. A common
and traditional approach where
students have passively accepted
information from teachers and
textbooks has been used in those
cases.
Everybody should be aware of
the presence of food additives in
many foodstuffs and about
adverse health effects caused by
excessive use of additives. It is nec-
essary, therefore, to teach basic
properties, role and necessity of
food additives in chemistry classes.
From the teaching method
point of view, food additives are a
very good material for creating
practical problem-solving situa-
tions in teaching of and learning
chemistry. Physical and chemical
properties of food additives can
be tested in simple ways in a
school lab setting. Current pre-
liminary research used such
teaching situation for formative
assessment of some acquired
knowledge and skills of students.
What did the students do with
food additives in the chemistry
class?
Food additives were taught to
high school seniors (17-18 years
old). Those students already com-
pleted general, inorganic, organic
and qualitative analytical chemis -
try courses and some biochem-
istry topics. Four periods were
used to teach food additives. This
paper describes in detail the lab
portion which consisted of one 
90 min session. The lab was pre-
ceded with a 45 min classroom
session which included an intro-
ductory test, conversation and
reading a text with some infor-
mation on additives (appendix 1).
After the lab, another 45 min
classroom session was held in
which the students were given a
follow-up test (appendix 2) and 
a survey (appendix 3).
Eighteen and nineteen stu-
dents (thirty-seven students
total), respectively, participated in
the two laboratory sessions. The
students were divided in groups
Group of additives Food additive name E number
1
Sodium acetate E262
Tartaric acid E334
Mannitol E421
Potassium hydrogen sulfite (Vinobran)* E228*
2
Sodium nitrite E249
Sodium nitrate E251
Boric acid E284
Sodium benzoate
(Konzervans/Preservative)*
E211*
3
Sodium acetate E262
Tartaric acid E334
Manitol E421
Sodium hydrogen carbonate (Prasak za
pecivo/Baking Soda)*
E500*
4
Sodium nitrite E249
Sodium nitrate E251
Boric acid E284
Citric acid (Limuntus)* E330*
Table 1. Groups of food additives given to students
* signifies additives in original packaging with their commercial names in 
Serbian/and English translation, where appropriate; the E numbers for those
additives were not given to the students.
of three (and one group of four)
mixing them to get a balanced
distribution based on their pre -
vious grades and performances.
Every group was given four addi-
tives (out of ten selected for
experiments). Every additive was
given to at least two student
groups. The food additive combi-
nations by groups are given in
the table 1.
What were the results 
of students’ activities?
The standard student curricu-
lum did not include a chapter on
additives. Therefore, it was
important to determine the stu-
dents’ baseline knowledge of
additives. The correct individual
student answers on the introduc-
tory test were 25-80 %, with an
even distribution. The introducto-
ry test gave a good indication
about the students’ previous
knowledge on additives. The low-
est score for the follow-up test
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Materials and products
– Test tubes and a rack, spoons, metal plate, beaker (for discarded solutions), paper towels.
– Additive samples (three of them in glass cups labeled with the corresponding E numbers,
and the fourth in the original commercial packaging). 
– 0.01 M hydrochloric acid and 0.01 M sodium hydroxide.
– Indicator solutions.
– Distilled water.
Sample number
Physical and chemical properties
Organic Inorganic Physical state Color Water solubility Range of pH
Table 2. The results obtained by testing four additives
Indicator
Color change
range (pH)
Color
In 0.01 M HCl In 0.01 M NaOH
Litmus 5.0-8.0
Methyl orange 3.1-4.0
Bromthymol blue 6.0-7.6
Table 3. Testing colors of indicators in 0.01 M hydrochloric acid 
and 0.01 M sodium hydroxide
Chemical name Formula
Tartaric acid HOOC-(CHOH)2-COOH
Potassium hydrogen sulfite KHSO3 
Boric acid H3BO3
Mannitol HOH2C-(CHOH)4-CH2OH
Sodium nitrate NaNO3
Sodium hydrogen carbonate NaHCO3
Citric acid
Potassium nitrite KNO2
Sodium benzoate NaC6H5COO
Sodium acetate NaCH3COO
Table 4. List of additives
Experimental part 
Every group of students
received the materials and pro -
ducts that you can see above.
They have to test given additives
and to record the following
properties in table 2, and then,
based on experimental results,
to propose one of ten list name
for each of the four additives
tested.
– Is an additive organic or
inorganic? The students drew a
conclusion after they heated the
additive on a metal plate with a
Bunsen burner (supervised by the
teacher).
– Physical state.
– Color.
– Water solubility.
– Acidity (pH).
The students used indicators
to determine acidities of addi-
tives. 0.01M hydrochloric acid
and 0.01 M sodium hydroxide
were provided for students. They
recorded the results in the table
3.
CH2COOH
HOCCOOH
CH2COOH
Appendix 1. Some information about additives
An additive is a chemical compound which is not con-
sumed as food, but added to food products during process-
ing and/or manufacturing, to improve certain properties of
foodstuffs. By a convention, every additive is assigned a
specific E number, following the International Numbering
System (INS).
By their origin, additives are classified as natural or
synthetic, and by composition, as inorganic or organic.
The functional (technological) classification in nine
groups is the most important (seven groups of additives
are listed here):
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was 30 %, and the highest, 90 %.
All students scored better on the
follow-up test than on the intro-
ductory test, but those results
were not directly comparable
since the tests were different. It
should be noted, however, that
almost 90 % of students scored
over 60 % on the follow-up test.
As described previously,
twelve groups of students were
formed and four additives 
were given to each group. The
total number of additives was
ten. Every additive was given to
at least two groups. Table 5
shows all groups of students suc-
cessfully identified additives
E334, E228, E211, E500 and E330.
Four of those (five additives) were
given to students in the original
(commercial) packaging (table 1),
which proved to be an important
identification clue. In addition, all
students collected sufficient data
to identify tartaric acid, E334. It
should be noted that every addi-
tive was identified by at least two
groups.
If we analyze results from
table 4 (second task), we can see
that the number of correct
answers was two to four. The
majority of the groups had two
correct answers (45 %), followed
by three (29 %) and all four cor-
rect answers had 26 % of the
groups.
The survey results show that
generally all students were
pleased to learn something
important from everyday life. The
opinion of the most of the stu-
dents was that food should be
included in chemistry curricu-
lums. The survey answers show
that there is a real need for such
inclusion. Students need educa-
tion to help them become edu-
cated consumers and be able to
make good health choices.
Conclusion
General population does not
have sufficient knowledge of addi-
tives which are unavoidable com-
ponents of food. Many additives
have harmful properties and are
usually components of products
primarily consumed by younger
generations. Learning about food
additives should be mandatory,
not optional, in any educational
system. Chemistry education,
which teaches the science of mat-
ter, has the leading role in such
learning. Through chemistry, stu-
dents will learn and understand
relationship between science, tech-
nology and society. Unfortunately,
introduction of such innovative
lessons is relatively slow and it is
really up to teachers to introduce
additives to their students.
We hope this paper will allevi-
ate that process.
Acknowledgements
This paper was supported by
the Ministry for Education and
Science of the Republic of Serbia
(project no. 179048).
References
AIKENHEAD, G. S. (1994). «What is
STS science teaching?». In:
SOLOMON, J.; AIKENHEAD, G. S.
[ed.]. STS education: International
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FENSHAM, P. J. (1985). «Science for
all». Journal of Curriculum Stu -
dies, 17(4): 415-435. 
KOROLIJA, J. N.; NOVAKOVIC, N.;
MANDIC, Lj. M. (2008a). «An
investigation of the properties
of vitamin C through a labora-
tory session». Journal of Science
Education (REC), 9(2): 109-112.
KOROLIJA, J. N.; PLAVSIC, J. V.; MLADENO -
VIC, I. M.; MANDIC, Lj. M. (2009).
«A contribution to Science for
all: Learning about polymers».
Problems of Education in the 21st
Century, 17: 107-118. 
— (2012).  «Beer as a teaching aid
in the classroom and labora-
tory». Journal of Chemical Educa-
tion, 89(5): 605-609.
KOROLIJA, J. N.; RAJIC, S.; MANDIC, Lj.
M. (2008b). «Education about
diet through chemistry learn-
ing». Problems of Education in
the 21st Century, 9(9): 65-73. 
KOROLIJA, J.; STANIŠIC´, J. (2009).
«Teaching science as a function
of connecting science, technolo -
gy and society». Zbornik Instituta
za Pedagoška Istraživanja, 41(2):
461-476. [In Serbian]
YAGER, R. E. (1990). «STS: Thinking
over the years». The Science
Teacher, 57(3): 52-55.
Groups
Additive
E334 E228 E421 E262 E284 E251 E249 E211 E500 E330
Total 4 2 4 4 4 4 4 2 2 2
Correct answers 4 2 2 2 2 3 3 2 2 2
Table 5. Success rate of identifying additives by the groups of students
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Colors (E100-E199)
Both natural and synthetic dyes are used for food coloring.
Dyes are added when the technological food processing
alters natural food color. Alternatively, food dyes are used
to enhance visual appeal of foodstuffs. It is important that
addition of dyes does not change other product properties.
Dyes are used in bakery products, meat products, non-
alcoholic beverages, ice creams, yogurts, soups, etc.
Preservatives (E200-E299)
Preservatives inhibit growth of microorganisms (bacteria,
yeast and mold). They are used in practically all processed
food (such as meats, fruit and vegetable products, sodas
etc.). Nitrites (E250) are officially listed as poisons. However,
they are still irreplaceable preservative for meat products
preventing growth of Clostridium botulinum, which produces
life threatening toxins. Nitrites toxicity can be kept under
control when they are used in mixture with table salt (0.5-
0.6 % nitrites).
Antioxidants & acidity regulators (E300-E399)
Antioxidants inhibit oxidation reactions and remove free
radicals. They are used in almost all kinds of foodstuffs. In
meat products they prevent oxidation of fatty acids. They
also prevent darkening of peeled/cut fruits and vegetables.
The well-known additives from this group are vitamin C
(E300) and citric acid (E330).
Flavor enhancers (E600-E699)
As the name says they improve and enhance food flavor.
They can be found in chips, meat products, chewing gums,
soups, spreads, spices, mustard, etc. Best known additives
from this group are glutamic acid and its salts. They acti-
vate certain receptors causing constant craving for pro -
ducts that contain them. Soy flakes are often added to
foodstuffs. They easily ferment becoming acidic. Addition
of monosodium glutamate (MSG, E621), neutralizes that
acidity.
Sweeteners (E950-E969)
Diet products frequently use sweeteners which have low
or zero calories, i. e. cannot be digested or participate in
metabolic processes. They can be found in non-alcoholic
beverages, candy, chewing gums, ice cream, sweets and
drugs. There have been some reports that sweetener
aspartame (E951) causes headaches, anxiety, perspiration
and breathing problems. Experiments on rats showed that
some symptoms of Parkinson’s and Alzheimer’s diseases
can be caused by aspartame.
Appendix 2. Follow-up test
1. Explain the term food additive.
2. Explain what is the acceptable daily intake (ADI) of
additives.
3. How are food additives classified by the composition?
4. Sodium salt of a non-essential amino acid is a food
additive E621:
a) Write the name and the molecular formula for that
amino acid.
b) How is this additive categorized by its functionality?
5. What is the reason for using sweeteners as sugar
replacement? Name one sweetener.
6. Are the food containing additives recommended for
children under the age of three and elderly population?
Elaborate.
7. Explain how you determined if an additive was organic
or inorganic in your experiments.
8. Complete the following sentences:
a) Food additives are water ____________.
b) Bromthymol blue changes its color from ____________
to ____________ within the pH rang of ____________.
Addition of one drop of this indicator makes the aque-
ous solution of the additive E262 turn blue. The solu-
tion of E262 has the concentration of hydronium or
hydroxyl ions of ____________.
c) Vitamin C, E ____________ and citric acid, E ___________
are additives from the group of ____________.
Ivana Mladenovic is a chemistry teacher at the Beauty Care High School in Belgrade. Jasminka Korolija is scientific associa-
te of Faculty of Chemistry in Belgrade. Her main research interest is research about learning through practical work and STS
approach. Ljuba Mandic is the head of Department of Biochemistry in the same University and she is author of many scien-
tific articles, books, etc. Igor Matijasevic is teaching assistant also at the same Faculty and his main research interest is 
learning through practical work. Dragan Marinkovic is working as a lead technical director at Jarrow Industries, Inc. (Santa
Fe Springs, CA, USA) and he is involved in incorporating everyday life as topics in modern chemistry curriculums. 
Ivana Mladenovic
ivanaar82@gmail.com.
Jasminka Korolija
korolija@chem.bg.ac.rs.
Ljuba Mandic
ljmandic@chem.bg.ac.rs.
Igor Matijasevic
igormat@chem.bg.ac.rs.
Dragan Marinkovic
quicha@gmail.com.


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