Staff Members of the Institute of Biochemistry, TU - Institut für ...
Staff Members of the Institute of Biochemistry, TU - Institut für ...
Staff Members of the Institute of Biochemistry, TU - Institut für ...
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Chemistry <strong>of</strong> Functional Foods<br />
Group leader: Michael Murkovic<br />
Graduate students: Alam Zeb, Yuliana Reni Swasti<br />
Diploma students: Katrin Julia Greimel, Thomas Binder, Irma Sliumpaite, Bahar Nahimi<br />
Zahabi, Ramune Bobinaite<br />
Technician: Alma Ljubijankic<br />
Honorary Pr<strong>of</strong>essor: Klaus Gün<strong>the</strong>r, Forschungszentrum Jülich, Germany<br />
Project Assistant: Sonja Thanner-Lechner<br />
General description<br />
Antioxidants have different functions depending on <strong>the</strong> location <strong>of</strong> action. Is it <strong>the</strong> protection<br />
<strong>of</strong> biological systems maintaining <strong>the</strong> integrity <strong>of</strong> <strong>the</strong> system or <strong>the</strong> protection <strong>of</strong> foods against<br />
oxidation leading to health threatening substances? The exposure to oxidation products is<br />
ei<strong>the</strong>r described as oxidative stress or <strong>the</strong> oxidized substances have an acute or chronic<br />
toxicity or are carcinogenic. The production <strong>of</strong> healthier and safer foods is <strong>of</strong> primary interest<br />
<strong>of</strong> this research group.<br />
The antioxidants <strong>of</strong> interest are polyphenols including anthocyanins and carotenoids. The<br />
evaluation <strong>of</strong> <strong>the</strong>ir occurrence in foods and <strong>the</strong>ir behavior during processing and cooking is<br />
important especially when <strong>the</strong>se substances are used as food additives. The safety evaluation<br />
<strong>of</strong> <strong>the</strong>se compounds includes <strong>the</strong> evaluation <strong>of</strong> possible degradation products.<br />
Heating <strong>of</strong> foods is a process that is normally done to improve <strong>the</strong> safety and digestibility and<br />
improve <strong>the</strong> sensory attributes like texture, color, and aroma. During <strong>the</strong> heating reactions<br />
occur that lead to <strong>the</strong> degradation <strong>of</strong> nutritive constituents like carbohydrates, proteins, amino<br />
acids and lipids. Some <strong>of</strong> <strong>the</strong> reaction products are contributing to <strong>the</strong> nice aroma, color, and<br />
texture <strong>of</strong> <strong>the</strong> prepared foods and many <strong>of</strong> <strong>the</strong>m are highly toxic and/or carcinogenic.<br />
However, <strong>the</strong>se hazardous compounds occur in ra<strong>the</strong>r low concentrations being normally not<br />
acute toxic. The substances have a very diverse chemical background like heterocyclic<br />
amines, polycondensated aromatic compounds, acrylamide or furan derivatives. The aim <strong>of</strong><br />
<strong>the</strong> research is to investigate <strong>the</strong> reaction mechanisms that lead to <strong>the</strong> formation <strong>of</strong> <strong>the</strong>se<br />
hazardous compounds and establish strategies to mitigate <strong>the</strong> formation and <strong>the</strong>reby reducing<br />
<strong>the</strong> alimentary exposure.<br />
Carotenoids <strong>the</strong>rmal oxidation in triacylglycerols<br />
β-Carotene is one <strong>of</strong> most important and widespread carotenoids present in food. It is an<br />
important source <strong>of</strong> provitamin A. It acts as antioxidant in biological systems including <strong>the</strong><br />
complex system <strong>of</strong> lipids. We studied <strong>the</strong> oxidation <strong>of</strong> β-carotene in model triacylglycerols<br />
system, comparable to most <strong>of</strong> <strong>the</strong> high oleic edible oil. An HPLC electrospray ionization<br />
mass spectrometric method was developed for <strong>the</strong> separation and identification <strong>of</strong><br />
triacylglycerols and its oxidation products (Figure 1). β-Carotene was found to act as<br />
antioxidant at lower temperature like 90 and 100 o C, while oxidation <strong>of</strong> triacyglycerols was<br />
closely correlated with <strong>the</strong> oxidation <strong>of</strong> β-carotene after 8 hours <strong>of</strong> <strong>the</strong>rmal oxidation at<br />
110 o C. The oxidized products <strong>of</strong> β-carotene were epoxides, peroxides and apocarotenals,<br />
separated and analyzed using C30 reversed phase HPLC-DAD and APCI-MS. We found that<br />
110 °C and 120 o C were <strong>the</strong> favorable temperatures for studying <strong>the</strong> oxidation reaction <strong>of</strong><br />
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