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Published: Kem. Ind. 52 (10) (2003) 495–499
Paper reference number: KUI-15/2003
Paper type: Conference paper
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Temperature Influence on Chemical Changes During the Extrusion Cooking

D. Kovaček, A. Ninčević Grassino, I. Miljević, D. Vikić-Topić, M. Brnčić, D. Ćurić, B. Tripalo, D. Ježek, D. Karlović and M. Fegeš


Extrusion cooking is one of many techniques used to proces a variety of foods. Many studies have shown that natural compounds in foodstuff may be reduced by manipulation of extrusion operation conditions in single or twin screw extruders. It is known that combinations of procesing parametars such as temperature, presure, and screw speeds may result in physical and chemical changes in the structure of biopolymers. The consequence of these modifications are changes in the nutritional value, functionality and biological activities of the main food components. In this research we investigated modifications of protein structure after disruption of protein body by extreme conditions of temperature and presure in extruder. The disruption of protein body is connected with formation of new kind of covalent bonds (disulfide and nondisulfide type) that result in protein cros-link. Here, we analysed nondisulfide cros-linking reactions using two approach. The first was based on molecular modeling, while the second one used spectroscopic analytical methods: FTIR with real samples- extrudates obtained by twin co-rotating extruder. Given results indicate that the higher temperature has more effect on formation of isopeptide bonds. The results of both applied methods have shown very good agreement, so we concluded that combinations of these methods can be used in analysis of protein macromolecules in complex samples such as food. This investigation has also shown that FT-IR spectroscopy is an excellent instrumental technique for following changes that occur during extrusion cooking. It is posible to follow little changes on protein molecules in the sense of isopeptide bond formation.

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extrusion, isopeptide bonds, molecular modelling, FT-IR spectroscopy