3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
Q u a n t i f i c a t i o n a n d Q u a l i t y
A s s u a r a n c e
The sample analysis was carried out in three repetitive.
Matrix-matched standards of samples were prepared as
described above with the only one difference, residue after
crude extract evaporation was dissolved in toxins standard
solution (methanol: water, 1 : 1, v/v). By means of described
analytical method the limits of detection were achieved
in range 0.5–5 ng ml –1 for measured mycotoxins.
Results
The levels of Fusarium toxins found in wheat grains,
whole-wheat flour and breads prepared by three alternative
procedures are summarized in Table I. Out of 8 monitored
target mycotoxins only nIV, DOn and its conjugates ADOns
and DOn-3-Glc were present at levels exceeded method detection
limits. no Fus-X, HT-2, T-2 and ZOn were found in
examined samples. It should be noted, that conjugated DOn
was contained in experimental wheat at relatively high level,
in this particular case the DOn-3-Glc: DOn ratio value was
approximately 3 : 10, while in previous studies the ratio was
reported to be 1 : 10 ref. 2 .
Within the baking experiments decrease of both DOn
and DOn-3-Glc occurred (up to 33 % and 49 %, respectively),
ADOns and nIV decreased below the limits of detection.
Although no significant differences in mycotoxins
levels were obtained in bread loaves prepared under various
experimental conditions, some indirect correlation between
DOn and DOn-3-Glc concentrations could be seen. The
longer was fermentation and proofing phase the lower was
DOn decrease, while decline DOn-3-Glc was higher. These
results indicate a potential breakdown of DOn-3-Glc during
bread-making yielding in free DOn. At the same time other
unknown transformations of these mycotoxins take place
resulting in overall lower trichothecenes levels in bread in
comparison with wheat taken into the process.
Table I
Levels of mycotoxins in wheat, flour and bread variations
Sample
Mycotoxins [μg kg–1 ]
DOn DOn-3-Glc ADOns nIV
Wheat 469 162 73 47
Flour 337 102 23 15
Bread-var.1 263 29 < 5 < 5
Bread-var.2 278 25 < 5 < 5
Bread-var.3 292 22 < 5 < 5
The data obtained in the second part of experiments concerned
with beers are presented in Table II. The majority of
beers contained detectable levels of DOn, ADOns and DOn-
3-Glc. Occurrence of DOn-3-Glc was shown in all of light
s695
Table II
Levels of mycotoxins in beers
Beer Mycotoxin Incidence Mean Range
[μg dm –3 ] [%] [μg dm –3 ] [μg dm –3 ]
DOn 82 12.9 1.5–33.7
Light DOn–3–Glc 100 16.3 3.2–38.0
ADOns 69 8.1 3.9–27.8
DOn 84 9.3 1.0–29.5
Dark DOn–3–Glc 92 11.0 2.5–40.2
ADOns 71 8.8 5.1–19.8
beer samples. Interestingly, its mean levels exceeded DOn
levels in light as well as dark beers. Although bioavailability
of DOn-3-Glc has not been documented until now, guestion
arises whether this “masked” DOn does not increase the
healt risk associated with trichothecenes dietary intake. The
relative ratio of DOn-3-Glc and DOn in beers ranged from
0.8 to 1.3.
Conclusions
The results obtained in this study can be summarized as
follows:
(i) Some decrease of Fusarium mycotoxins including
DOn and its major conjugates ADOns and DOn-3-Glc occurred
during baking.
(ii) no significant impact of the tested technological
times (proofing and fermentation) was observed.
(iii) Extensive contamination of beers obtained at Czech
market demonstrated. The levels of DOn, ADOns and DOn-
3-Glc in light and dark beers were comparable, the later compound
was dominating.
This study was carried out within the scope of research
projects NPV II, 2B08049 supported by the ministry of Education,
Youth and Sports of the Czech Republic.
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