3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures
3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures
3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures
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Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology<br />
P17 ExTENSION OF ASPARAGINASE<br />
APPLICATION TO ACRyLAMIDE<br />
MINIMIZATION FROM POTATO TO CEREAL<br />
PRODuCTS<br />
ZUZAnA CIESAROVáa , KRISTínA KUKUROVáa ,<br />
ALEnA BEDnáRIKOVáa and FRAnCISCO J.<br />
MORALESb aVÚP Food Research Institute, Priemyselná 4, 824 75 Bratislava,<br />
Slovak Republic,<br />
bCSIC Consejo Superior De Investigaciones Cientificas, Instituto<br />
Del Frio, José Antonio Novais 10, E-28040 Madrid, Spain,<br />
ciesarova@vup.sk<br />
Introduction<br />
Acrylamide is a suspected human carcinogen, formed in<br />
fried and baked carbohydrate-rich foodstuffs such as potatoes<br />
and cereals. The free amino acid asparagine and reducing<br />
sugars are considered as the main precurosrs 1 .<br />
A number of raw material pre-treatments were<br />
investigated which could mitigate acrylamide formation. Unfortunately,<br />
most of them may also have an impact on the<br />
product sensory quality. For example, the acidification may<br />
result in a sour product taste, the addition of amino acids<br />
may generate unpleasant off-flavours upon heating or in the<br />
case of calcium chloride addition, product texture might be<br />
improved, but on the other hand it causes a bitter aftertaste 2 .<br />
However, the application of L-asparaginase enzyme before<br />
heat treatment results in a sufficient decrease of acrylamide<br />
amount with no undesirable impact on sensory quality of<br />
final products 3 .<br />
The aim of this work was an extension of enzymatic way<br />
of acrylamide elimination in potato products 3 to cereal of rosquillas<br />
type in collaboration with CSIC Institute del Frio in<br />
Spain. In addition, the impact on the sensory quality of products<br />
prepared with L-asparaginase was evaluated.<br />
Experimental<br />
L-asparaginase (novozymes, Denmark) produced by<br />
Aspergillus oryzae was applied in simulated potato and cereal<br />
matrices and food products on potato and cereal base such as<br />
potato pancakes and typical Spanish cereal product named<br />
rosquillas (Spanish doughnuts), respectively. Following ana-<br />
lytical parameters were determined:<br />
•<br />
•<br />
•<br />
Saccharides using HPLC/RI according to ref. 4<br />
Amino acids using LC/MS/MS according to ref. 5<br />
Acrylamide using LC/MS/MS according to ref. 6<br />
The content of main acrylamide precursors (monosaccharides<br />
and amino acid asparagine) were analysed in raw<br />
material. The conversion of asparagine to aspartic acid and<br />
final acrylamide content after heat treatment was observed.<br />
In potato pancakes the preliminary sensory evaluation<br />
was done using a dual method. An appearance, colour, texture<br />
and selected descriptors of taste and aroma were deter-<br />
s610<br />
mined using 0–5 point scale. Five trained assessors payed an<br />
extraordinary attention to offlavour detection.<br />
P o t a t o M a t r i x<br />
Before the enzyme application in food products, the<br />
appropriate conditions of L-asparaginase incubation (time<br />
and temperature) were tested in simulated matrices. Potato<br />
matrix consisted of the main acrylamide precursors (asparagine<br />
and glucose), potato starch and water in typical proportions:<br />
asparagine and glucose were used in equimolar ratio and<br />
content of water was 80 %. Potato starch was dried before<br />
the application to matrix in the ratio of 1 : 0.2 with mixture of<br />
asparagine and glucose.<br />
C e r e a l M a t r i x<br />
Cereal matrix simulated Spanish cereal products recipe<br />
for rosquillas preparation and was composed of asparagine,<br />
glucose, fructose, wheat starch and water. Glucose and fructose<br />
were used in equimolar ratio and in 1 : 4 ratio with starch<br />
in a final mixture. Potency of 3 levels of asparagine (0.1, 0.5<br />
and 1.0 %) were compared. Content of water in cereal matrix<br />
was 50 %.<br />
A s p a r a g i n a s e A p p l i c a t i o n<br />
L-asparaginase was applied in concentrations of 2 and<br />
10 U g –1 to simulated potato matrix or 0.1, 0.5 and 1.0 U g –1<br />
to simulated cereal matrix. The enzyme was incubated at 20,<br />
37, 50, 60 and 70 °C for 5, 10, 20, 30 and 60 min in thermostat<br />
(Fried Electric, Haifa, Israel). Subsequently L-asparaginase<br />
was applied to different potato varieties (Marabel and Bellarosa)<br />
purchased from local Slovak market in concentrations<br />
of 1 and 2 U g –1 , respectively, to potato pancakes (potatocereal<br />
food product) in concentration of 1 U g –1 , and to cereal<br />
product rosquillas in concentrations of 100 and 500 U kg –1 of<br />
flour. L-asparaginase in food samples was incubated at 37 °C<br />
for 10 and 15 min, respectively.<br />
T h e r m a l T r e a t m e n t<br />
For potato matrix 0.2 g of glucose and asparagine<br />
mixture, 1 g of potato starch was weighed into the vial and<br />
4 ml of water (control sample) or 4 ml of enzyme solution<br />
with required concetration was added and in next step, after<br />
enzyme incubation, treated at 180 °C for 20 min in thermoblock<br />
(Liebisch Labortechnik, Bielefeld, Germany).<br />
For cereal matrix 0.24 g of glucose and fructose mixture<br />
and 0.76 g of wheat starch was weighed into the vial, 0.76 ml<br />
of asparagine solution (concentration of 0.1, 0.5 and 1.0 g in<br />
per 100 ml) in control sample or 0.38 ml of asparagine solution<br />
(concentration 0.2, 1.0 and 2.0 g per 100 ml) and 0.38 ml<br />
of enzyme solution with demanded concentration was added.<br />
Vials were incubated and heated at 190 °C for 15 min in thermoblock.<br />
Then, samples were cooled to room temperature and<br />
final content of acrylamide was determined.