Identification of origin of sugar samples in Turkey
by determination of carbon isotope ratio
Herkunftsbestimmung des Zuckers in der Türkei
mit Hilfe des Kohlenstoff-Isotopenverhältnisses
M. Jale Leblebici
Since the cost of cane sugar is much lower than that of beet sugar,
although both have the same qualities, beet sugar production can
only be sustainable where high tariff barriers are applied. Therefore sugar smuggling is attractive for smugglers for those countries in which sugar is produced from sugarbeet like Turkey. The
fact that using conventional analysis to make a distinction between
cane sugar and beet sugar is very difficult, because they have the
same quality parameters in international white sugar standards,
encourages the smuggling activities. The Turkish Sugar Authority
started a study to control sugar smuggling by means of distinguishing beet sugar and cane sugar by carbon isotope ratio (CIR) with
regard to difference between sugarbeet’s and sugarcane’s carbon
fixation process. This study showed that CIR determination is a
very successful tool for determining whether a sugar sample is produced from sugarbeet or sugarcane with the assistance of law-enforcement officers who take sample from suspicious sugar parties
to control sugar smuggling activities in those countries in which
sugar is only produced from sugarbeet.
Da die Kosten der Rohrzuckergewinnung viel geringer als die der
Rübenzuckergewinnung sind – obwohl beide Zucker die gleiche
Qualität aufweisen – ist die Rübenzuckergewinnung nur dort wirtschaftlich vertretbar, wo hohe Zollschranken bestehen. Deshalb
ist Rohrzuckerschmuggel in jene Länder attraktiv, in denen Zucker aus Zuckerrüben gewonnen wird, wie z.B. in die Türkei. Der
Schmuggel wird dadurch verstärkt, dass mit Hilfe konventioneller
Analysen eine Unterscheidung zwischen Rohr- und Rübenzucker
aufgrund der gleichen Qualitätsparameter internationaler Weißzuckerstandards sehr schwierig ist. Die türkische Zuckerbehörde
startete eine Untersuchung zur Kontrolle des Zuckerschmuggels
mittels des charakteristischen Kohlenstoff-Isotopenverhältnisses
im Hinblick auf den Unterschied der Kohlenstofffixierung bei Rüben- und Rohrzucker. Diese Untersuchung erwies sich als eine sehr
erfolgreiche Maßnahme zu Herkunftsbestimmung von Zuckerproben, die unter staatlicher Aufsicht genommen wurden.
Stichwörter: Kohlenstoff-Isotopenverhältnis, Rübenzucker, Zuckerschmuggel, Kohlenstoff-Fixierung
Key words: carbon isotope ratio, beet sugar, sugar smuggling, carbon fixation
1 Introduction
Turkey is a Eurasian country which stretches across the Anatolian
peninsula in western Asia and Thrace (Rumelia) in the Balkan region of southeastern Europe. In Turkey white sugar (sucrose) is
produced from sugarbeet. Average figures of the Turkish sugar sector are given in Table 1.
Turkey is the fourth largest beet sugar producer in the world following the EU, the USA and Russia and is the third largest in the
Europe, following the EU and Russia in the 2007/08 marketing
year. Turkey’s share in the world was 6% of beet sugar production
for the 2007/08 marketing year.
Table 1: Turkish sugar sector data (2006–2009)
Beet sugar production in mn t/a
Sugarbeet sliced in mn t/a
Number of operating sugar factories
Number of sugar companies
Number of sugarbeet growers
Harvested sugarbeet area in ha
2
15
33
7
300,000
300,000
Sugar Industry / Zuckerindustrie 134 (2009) No. 10, 629–632
Turkish Sugar Law no.4634 came into force in 2001 to establish
sugar policy to define procedures and principles in sugar production, and to set up pricing and marketing conditions and methods,
with a view to meeting domestic demand with domestic production
and to export when necessary. The main tool of the Sugar Law is
the quota system. In order to maintain stability in sugar production
and in sugar supply the amount of sugar to be marketed is determined by quotas.
The Turkish Sugar Authority, the regularity body of the Turkish
Sugar Sector was set up in order to ensure application of the Sugar
Law and other related regulations, to monitor the applications and
to conclude them, to perform necessary arrangements within the
powers given by the Law, and to perform other duties assigned
and to exercise other powers granted by the Law. Since the main
purpose of Turkish Sugar Authority is to secure supply:demand
balance in the domestic sugar market, controlling the supply of
smuggled sugar and off-the-record sugar is among the responsibilities of the Authority.
Because the climatic conditions are not suitable for cane cultivation, sugar can only be produced from sugarbeet in Turkey. Due to
the fact that the cost of cane sugar is much lower than that of beet
629
Table 2: Results of some studies on C3 and C4 plants’ carbon
isotope ratios
Carbon isotope ratio range
C3 plant
C4 plant
Reference
–22 to –30
–23 to –30
–22 to –35
–24 to –32
Sanford [1]
Calderone et al. [2]
Croft [3]
Sandusky und Steven [4]
–8 to –11
–10
–8 to –20
–10 to –16
sugar, although both have the same qualities, beet sugar production
can only be sustainable if high tariff barriers are applied. Therefore
sugar smuggling is attractive for smugglers in those countries in
which sugar is produced from sugarbeet. Just because white sugar
(sucrose) obtained from cane and beet has the same quality parameters in white sugar standards, to make distinction between cane
sugar and beet sugar is very difficult using conventional analysis.
This reality encourages sugar smuggling activities in the countries
like Turkey in which sugar is produced from beet.
On the other hand, there is a difference between sugarbeet and
sugarcane in terms of their carbon fixation process. It is known
that carbon fixation is a process found in autotrophs (organisms
that produce their own food), usually driven by photosynthesis,
whereby CO2 is changed into organic materials. A C3 plant that
uses the Calvin cycle for the initial steps that incorporate CO2 into
organic matter, forms a 3-carbon compound as the first stable intermediate. Most broadleaf plants and plants in the temperate zones
are C3 plant like sugarbeet. A C4 plant is one which prefaces the
Calvin cycle with reactions that incorporate CO2 into a 4-carbon
compound. C4 plants have a distinctive leaf anatomy. This pathway is found mostly in hot regions with intense sunlight. Tropical
grasses, such as sugarcane and maize are C4 plants, but there are
many broadleaf plants such as sorghum, finger millet, amaranth
and switchgrass that are C4.
Carbon isotopes are strongly fractionated by photosynthesis and
the C3 and C4 processes involve different isotopic fractionation,
with the result that C4 plants have higher d13C values (13C/12C ratio
is the d13C value) ranging from –17 to –9 with a mean of –13 while
C3 plants show delta values ranging from –32 to –20 with an average value of –27. Accordingly, the different 13C/12C ratios can be
used to distinguish C3 from C4 plants. Results of some studies on
C3 and C4 plants carbon isotope ratios are summarized in Table 2.
Furthermore, there are a few studies on the carbon isotope ratio
(CIR) of sugar. However those few studies show that it is possible
to distinguish between sucrose from C3 plants (sugarbeet) and C4
plants (sugarcane). According to these studies; the carbon isotope
ratio:
– ranges from –10.3 to –12.2 as shown by Bricout and Fontes [5]
for sucrose from sugarcane (e.g. from The Antilles, Réunion,
Australia, and Madagascar);
– ranges from –25.1 to –26.0 as shown by Bricout and Fontes [5]
for sucrose from sugarbeet from France, Italy and Germany;
– is –11.59 for sucrose from sugarcane and –25.62 for sucrose
from sugarbeet as shown by Jahren et al. [6].
The Turkish Sugar Authority started a study to control sugar
smuggling by means of distinguishing beet sugar and cane sugar by
carbon isotope ratio in the light of above information.
In Turkey:
– the raw material of sugar produced domestically is only sugarbeet,
– the main raw material of smuggled sugar is sugarcane due to the
lower cost than that of beet,
630
– the origin of legally imported sugar must be written on the label
of all the sugar packages together with the approval of the Agricultural and Rural Affairs Ministry.
Because that, sugar packages, on which the origin is not written on
the label, can be classified as suspicious. If the origin of a suspicious sugar sample is determined as sugarcane, it will be judged
that the sugar is smuggled because it must have a label showing
the origin of sugar in case it is imported legally. There is no doubt
that it is not easy to distinguish whether sugar is smuggled or not
in case the sugar were produced from beet in another country. But
fortunately, the probability of this being the case is low due the
higher cost of beet sugar.
2 Materials and methods
2.1 Sample
In this study, white sugar samples produced under the quota system in 33 sugar factories in Turkey during 3 campaigns (2006/07,
2007/08, 2008/09) were used. A campaign average sample of each
factory for each campaign was prepared from collected daily sugar
samples taken from white sugar produced in the relevant factory
every half hour during the entire campaign for the reference value
of carbon isotope ratio value in beet sugar produced in Turkish
sugar factories. Suspicious sugar samples sent to the Turkish Sugar
Authority by the office of the public prosecutor in Turkey were used
to determine whether the sample was beet sugar or cane sugar.
2.2 Methods
At the beginning of the study, collected white sugar samples (16
samples) from some of the sugar factories were sent to two different laboratories to determine the 13C/12C isotope ratio for a preliminary study. 13C/12C isotope ratio data obtained in two different
laboratories and results of statistical test (Student’s t-test) applied
to the data are shown in Table 3.
Although average values of isotope ratios found in two laboratories
are slightly different, the result of the t-test shows that the difference is not statistically important with a confidence level of 95%.
As a result of the preliminary study, Laboratory 1 (Lab 1) is chosen for the forthcoming determinations and Laboratory 2 (Lab 2)
was chosen for random control of results. Collected white sugar
samples from each factory were sent to Lab 1 to determine 13C/12C
isotope ratio of the samples. Confidentiality is one of the most important aspects of this study and in order to prevent the smugglers
from interfering with the results of analysis, all the samples were
sent to the laboratories only with a code number without any other
Table 3: Results of 13C/12C isotope ratio analyses and results of
statistical test (Student’s t-test)
Isotope ratio analyses
Number of samples
Average
Standard deviation s
Results of t-test
Degree of freedom
t-value tcritical (p = 0.05)
Laboratory 1
Laboratory 2
16
24.198
0.451
16
24.619
0.559
30
0.0263
1.697
Sugar Industry / Zuckerindustrie 134 (2009) No. 10, 629–632
sign on them. The code numbers were kept in only one record.
Samples and reference materials (for sucrose NIST-RM 8542; for
glutamic acid NIST-RM 8573) were burnt separately in ConfloIII
– Elemental Analyzer (Flash EA 1112 Series) and the gases formed
in the analyzer were passed to a Thermofinnigan MAT 253 IR-MS
instrument by means of helium gas (of 99.999% purity) in order to
determine the carbon isotope ratio in Lab 1.
3 Results and discussions
As is shown in Table 4, the average of carbon isotope ratio (CIR)
13
C/12C of sugar produced from beet in Turkey was found as 24.4
as a result of the study carrying out with 3 years campaign average
sugar samples from all sugar factories and it was found that the
carbon isotope ratio of sugar produced from beet in Turkey lies
between 23.7 and 25.6.
The CIR values change depending on region and time slightly. The
average standard deviation s of CIR values of the sugar samples
produced in factories in different campaigns was 0.153, lying between 0.034 and 0.324. On the other hand, the average standard
deviations of CIR values of the sugar samples produced in the different campaigns lies between 0.289 and 0.423.
Additionally, there was not any relationship between the CIR value
and the quality parameters of beet other than sugar content. The
overall correlation coefficient between CIR and sugar content (by
polarimetry) of beet was found as –0.55394 which is not so high
and not so low.
Table 4: Carbon isotope values of beet sugar produced in Turkish sugar factories between 2006 and 2009
Factory
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
2006/07
2007/08
2008/09
Average
s
RSD
23.87
23.79
23.83
24.12
24.19
24.07
*
24.32
24.16
24.05
24.17
24.35
24.50
24.43
24.40
24.36
24.23
24.37
24.56
24.46
24.39
*
24.60
24.90
24.52
24.48
24.62
24.73
24.61
24.88
25.04
25.26
25.55
23.73
23.96
23.86
24.07
23.91
23.83
24.06
24.15
24.45
24.32
24.13
24.22
24.02
24.20
24.47
24.28
24.22
24.35
24.51
24.54
24.44
24.58
24.43
24.29
24.51
25.00
24.81
24.78
25.10
25.10
25.11
25.42
25.10
24.09
24.03
24.09
23.80
24.09
24.37
24.12
23.91
23.79
24.06
24.36
24.11
24.21
24.13
24.03
24.30
24.71
24.54
24.21
24.32
24.64
24.42
24.51
24.54
24.74
24.32
24.38
24.65
24.52
24.84
24.73
24.67
24.78
23.90
23.93
23.93
24.00
24.06
24.09
24.09
24.13
24.13
24.14
24.22
24.23
24.24
24.25
24.30
24.31
24.39
24.42
24.43
24.44
24.49
24.50
24.51
24.58
24.59
24.60
24.60
24.72
24.74
24.94
24.96
25.12
25.14
0.149
0.099
0.116
0.140
0.117
0.219
0.029
0.168
0.268
0.125
0.101
0.098
0.199
0.129
0.192
0.034
0.228
0.087
0.155
0.092
0.109
0.082
0.072
0.248
0.104
0.290
0.174
0.053
0.255
0.114
0.166
0.324
0.316
0.6
0.4
0.5
0.6
0.5
0.9
0.1
0.7
1.1
0.5
0.4
0.4
0.8
0.5
0.8
0.1
0.9
0.4
0.6
0.4
0.4
0.3
0.3
1.0
0.4
1.2
0.7
0.2
1.0
0.5
0.7
1.3
1.3
24.42
0.423
1.7
24.33
0.289
1.2
24.40
0.330
1.4
0.153
0.6
ø
24.45
s
0.389
RSD (%) 1.6
* Sample not available.
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Table 5: Origin of suspicious sugar samples
Date
Cane sugar
Beet sugar
Number
Number
November 2007
December 2007
January 2008
February 2008
March 2008
April 2008
May 2008
June 2008
July 2008
August 2008
September 2008
October 2008
November 2008
December 2008
January 2009
February 2009
March 2009
April 2009
May 2009
June 2009
Total
9
34
72
13
48
24
14
21
3
1
3
8
0
0
4
2
1
3
2
1
263
15
7
27
1
9
2
2
10
2
6
7
0
1
2
1
6
8
3
3
6
118
Total number
of suspicious
samples sent
24
41
99
14
57
26
16
31
5
7
10
8
1
2
5
8
9
6
5
7
381
Results of the analyses were used to determine whether the sugar samples were produced from sugarbeet in Turkey or produced
from cane. In Turkey – as mentioned before – the raw material of
produced sugar is only sugarbeet, the main raw material of smuggled sugar is sugarcane due to lower cost and the origin of legally
imported sugar must be written on the label of all the sugar packages together with the approval of Agricultural and Rural Affairs
Ministry.
If the origin of a suspicious sugar sample is determined as sugarcane, it will be decided that the sugar is smuggled since it must
have a label showing the origin of sugar in case it is imported legally. CIR values were sent by the office of the public prosecutor
in order to help the court to decide on whether the suspicious sugar
was smuggled or not. The origin of suspicious samples are shown
in Table 5 and Figure 1 from the beginning of the study (November
2007) on a monthly basis.
As can be seen from Table 5, both the number of suspicious samples sent and the number of cane sugar samples determined were
Fig. 1: Origin of suspicious sugar sample
631
reduced sharply after this method was started to apply. Figure 1
also obviously shows that, the number of smuggled sugar samples
and number of smuggling activities were reduced by the application of the method.
4 Conclusion
It was seen that, CIR determination is a very successful tool to control sugar smuggling. Before the application of this method, sugar
smuggling was a very attractive job, without any risk of determining whether it was smuggling or not. But now, sugar smuggling has
lost its attraction in Turkey. As a result, this method introduced a
new approach in order to control sugar smuggling in Turkey.
Acknowledgement
This study was financed by the Turkish Sugar Authority the regularity body of Turkish Sugar Sector. The author would like to express sincere thanks to President M.A. Aksu and the other members
of Turkish Sugar Board which is the decision maker of Turkish
Sugar Authority. The author would like to thank also to all security
forces in Turkey for taking the samples from suspicious sugar and
sending to the Turkish Sugar Authority; to Turkish Sugar Authority
staff working on this study for their meticulousness and concealment and to Dr. F. Leblebici for giving the idea to start such a study
and for his valuable support.
Abbreviations
RSD
Relative standard deviation
s
Standard deviation
References
1 Sanford, T. (1995): Testing for Adulteration – A Federation Focus. American
Bee Journal 135, 343
2 Calderone, G.; Holland, M.; Reniero, F.; Guillou, C. ( 2005 ): An Overview
of Isotopic Analysis for the Control of Alcoholic Drinks, Alcohol and Spirits. European Commission Joint Research Center – Institute for Health and
Consumer Protection Publication. EUR 21875 EN, PB/2005/IHCP/1194
2 Croft, L.R. (1987): Stable Isotope Mass Spectrometry in Honey Analysis.
Trends in Analytical Chemistry 6, 206–209
4 Sandusky, P.; Steven, H. (2005): The Use of Site Specific Natural Isotope
Fractionation NMR Spectroscopy (SNIF-NMR) to Detect Sugar Adulteration in Fruit Juices and Spirits. Customs and Border Protection Laboratory
Bulletin 12, 27–42
5 Bricout J.; Fontes J. (1974): Distinction analytique entre sucre de canne et
sucre de betterave. Ann. Flas. Exp. Chem. 716, 211–215
6 Jahren, A.H., et al. (2006): An Isotopic Method for Quantifying Sweeteners
Derived from Corn and Sugar Cane. American Journal of Clinical Nutrition
84, 1380–1384
Identification de l’origine d’échantillons de sucre en
Turquie par détermination de la teneur isotopique du
carbone (Résumé)
Étant donné que le coût du sucre de canne est beaucoup plus bas
que celui du sucre de betterave, même si les deux ont les mêmes
qualités, la production du sucre de betterave n’est tenable économiquement que si des tarifs douaniers élevés sont appliqués. C’est
pourquoi la contrebande du sucre est attractive pour les fraudeurs
dans les pays dans lesquels le sucre est produit à partir de betteraves comme en Turquie. Faire la distinction entre le sucre de betterave et le sucre de canne par des analyses conventionnelles est
très difficile parce qu’ils ont les mêmes paramètres de qualité dans
les standards internationaux pour le sucre blanc, ce qui encourage
les activités des fraudeurs.
L’Autorité Turque Responsable pour le Sucre a entrepris une étude
pour contrôler la contrebande du sucre au moyen d’une méthode
permettant la distinction entre sucre de betterave et sucre de canne
par la teneur isotopique du carbone (CIR) en considérant la différence dans le processus de fixation du carbone entre la betterave et
la canne à sucre. Cette étude a montré que la détermination du CIR
est un outil très utile pour déterminer si un échantillon de sucre provient de betterave ou de canne à sucre, étude faite avec l’aide des
autorités officielles qui ont prélevé des échantillons douteux pour
contrôler les activités de contrebande du sucre dans les pays où le
sucre provient uniquement de la betterave.
Determinación del origen del azúcar en Turquía mediante la proporción de isótopos de carbono (Resumen)
Puesto que los gastos de la producción de azúcar de caña son mucho menores que los gastos de la producción de azúcar de remolacha, a pesar de que ambos azúcares tienen la misma calidad, la
producción de azúcar de remolacha solamente es justificable económicamente en países con alta arancelaria. Por esto el controbando de azúcar de caña tiene gran atracción en países que producen el
azúcar de la remolacha como, por ejemplo, Turquía. Los patrones
internacionales para la calidad del azúcar blanco dificultan el análisis convencional, lo que, a su vez, aumenta el contrabando aún
más. Las autoridades del azúcar turcas llevaron a cabo un estudio
acerca del control del contrabando de azúcar mediante la proporción característica de isótopos de carbono en vista de la fijación
distinta de carbono en azúcar de caña y de remolacha. Este estudio
resultó ser una medida eficaz para la determinación del origen de
muestras de azúcar tomadas bajo la vigilancia por el estado.
Author’s address: M. Jale Leblebici, Secretary General of the Turkish Sugar Authority, Oguzlar Mah. Çetin Emeç Boulevard No. 46,
06520 Balgat/Ankara, Turkey; e-mail: [email protected]
632
Sugar Industry / Zuckerindustrie 134 (2009) No. 10, 629–632