3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
P53 TRANS FATTy ACIDS IN DIET OF ThE CZECh
POPuLATION DuRING yEAR 2007
JAnA HRADILOVá, IREnA řEHůřKOVá, JIří
RUPRICH, SYLVA SALáKOVá and DAGMAR
PEČInKOVá
National Institute of Public Health, Centre for the Hygiene of
Food Chains, Palackého 3a, 612 42 Brno, Czech Republic,
hradilova@chpr.szu.cz
Introduction
The topic “trans fatty acid” recently appears as a problem
of growing interest. This is especially due to the relationship
to negative health impact of these fatty acids.
Unsaturated fatty acids can have the same chemical formula
but different chemical and consequently also physiological
properties due to different geometrical configuration.
The double bond of the unsaturated fatty acid can be in either
cis or trans configuration. In nature most unsaturated fatty
acids are in a cis configuration. This means that the hydrogen
atoms are on the same side of the two carbons of the double
bond. In the trans configuration, the hydrogen atoms are on
the opposite side of the two double bond carbons.
Trans fatty acids (TFA) are formed in technological and
microbiological processes by isomerization of cis double
bonds to trans double bonds. Small amounts of trans fat are
produced in the rumen of ruminants and then found in dairy
and beef fat. Trans fats are predominately and not-intentionally
produced commercially in large quantities through a
process called partial hydrogenation used to protect foods
from spoilage. The goal of partial hydrogenation is to add
hydrogen atoms to unsaturated fats, making them more saturated.
These more saturated fats have a higher melting point,
which makes them attractive for baking and extends their
shelf-life. These more stable fats are used in margarines and
shortenings. Most of the trans fats are found in foods made
with or fried in partially hydrogenated oils (margarines, highfat
baked goods, especially doughnuts, cookies, pastries and
crackers). The trans fat content of these foods may be as high
as 45–50 % of the fat.
High intakes of TFA may have an influence on total cholesterol.
Trans fats increase levels of LDL (so-called “bad”
cholesterol) and also lower levels of HDL (so-called “good”
cholesterol). TFA increase the risk of coronary heart disease
and of other chronic health problem (cancer, diabetes, obesity,
interfility).
Several countries and the World Health Organization
(WHO) have taken regulatory initiatives on the intake of
TFA levels and proposed revisions to the criteria for nutrient
content claims. The United States Food and Drug Administration
(FDA) issued a regulation requiring manufacturers to
list trans fat on the nutrition Facts panel of foods and some
dietary supplements. With this rule, consumers will have
more information to make healthier food choices that could
lower their consumption of trans fat as a part of heart-health
diet. The WHO has tried to balance public health goals with
s689
a practical level of trans fat consumption, recommending
in 2003 that trans fat be limited to less than 1 % of overall
energy intake. 1–7
The important input highlighting problems and questions
around TFA in the Czech diet was an opinion of the
Scientific Committee on Foods (VVP) 8,9 . This opinion was
requested by the Czech Ministry of Health as a reaction on
the open letter written by the group of Czech researchers criticizing
content of TFA in some foods (shortening fat, cakes
and biscuits, where TFA is main element – 50 % of all fatty
acids content) placed on a market and requesting obligatory
labeling similar to that used in the USA or in Denmark. The
VVP repeated some ideas of EFSA and measures which can
help to reduction the amount of TFA in foods. The VVP also
recommended to analyse food samples representing current
Czech diet to estimate main dietary sources and their influence
on the total TFA intake 8,9 .
The national Institute of Public Health in Prague, Centre
for the Hygiene of Food Chains in Brno, is responsible to
organize and perform longitudinal monitoring project named
“Dietary Exposure to Selected Chemical Substances”. In the
framework of this project fatty acids have been monitored
since 2005 10 .
Material and Methods
Fatty acids were determined in food samples representing
so-called food basket of the Czech population. 268 various
food samples were collected for analyses of FA in 2007
(food samples are collected in 12 places which create 4 regions
in the Czech Republic). Samples were culinary treated so
that they could be analysed in the same stage as they are consumed.
The result of the preanalytical treatment is a homogenous
sample of cooked foods, which is then analysed 11 . One
sample (mixture of samples from 3 places) represents composite
sample for each region (A, B, C, D).
The analytical procedure consists of the three consequent
steps - extraction of the triacylglycerols from the matrix,
saponification and ester interchange with methanol and finally
analyse methylesters of fatty acid using the GC – FID method.
After culinary treatment and pre-homogenisation the samples
were homogenized and extracted with mixture of petroleum
ether/acetone (ratio 2 : 1) as a solvent by homogenizator (high
frequency of revolutions) or by using of a hot solvent. Triacylglycerols
of the extracted fat were saponified and ester
interchanged with methanol. Methylesters of fatty acid were
shaken out with hexan, dried, filtrated and then were analysed
by gas chromatograph (TRACE GC) with flame ionization
detection, split/splitless injection and capillary column (SP
2560, 100 m × 0,25 mm, thickness of film 0,2 µm). Standard
Supelco 37 Component FAME Mix was used.
The method was validated using EffiValidation 3.0 software.
The accuracy of the method was confirmed by analysing
CRMs. Analytic quality control was implemented by
participating in proficiency testing organised within Food
Analysis Performance Assessment Scheme (FAPAS) of the
Central Science Laboratory York (UK). Used method is