Keywords: Maillard reaction, sugar isomerisation, kinetics, multiresponse modelling, brown colour formation, lysine damage, mutagenicity, casein, monosaccharides, disaccharides, aldoses, ketoses</p><p>The aim of this thesis was to determine the kinetics of the Maillard reaction between proteins and sugars, taking into account other simultaneously occurring sugar reactions. Model systems of foods, consisting of the protein casein and various sugars in a buffered solution, were studied. The reaction conditions were varied, covering relevant heating conditions for foods. The kinetics of the reactions were studied by means of multiresponse modelling.</p><p>The main reaction routes that were established in heated sugar-casein systems were (i) isomerisation of the aldose sugars into ketose sugars and vice versa, (ii) degradation of the sugar into carboxylic acids and unidentified products and (iii) the Maillard reaction between the sugar (degradation products) and the protein. In the Maillard reaction, the aldose sugars (like glucose and lactose) reacted with the<FONT FACE="Symbol">e</font>-amino group of lysine residues of the protein to form the Amadori product. Under the conditions studied in this thesis (90-130°C; pH 6.8) it was shown that ketose sugars (like fructose and lactulose) themselves were not reactive in the Maillard reaction. Therefore, the expected Heyns compound could not be detected. The degradation products of the sugars and Amadori products reacted in the Maillard reaction with either the<FONT FACE="Symbol">e</font>-amino group of the lysine residues or the guanidine groups of the arginine residues of the protein to form the brown-coloured melanoidins. The Maillard reactivity of the sugar degradation products was found to be much higher than that of the aldose sugars themselves. The formation of these reaction intermediates was, however, highly temperature dependent. The reaction mechanism of disaccharide sugars was roughly in accordance with that of monosaccharide sugars, with the difference that some sugar degradation pathways were hindered by the glycosidic bound sugar while others were favoured.</p><p>The multiresponse modelling approach as used in this thesis appeared to be a very powerful tool to unravel complicated reaction routes as occur in the Maillard reaction. The observed differences in reaction mechanism and reaction rate between the various studied sugars can be used to direct food quality aspects like browning, loss of nutritive value due to lysine damage and formation of mutagenic compounds.
|Qualification||Doctor of Philosophy|
|Award date||22 Feb 2002|
|Place of Publication||S.l.|
|Publication status||Published - 2002|
- maillard reaction
- maillard reaction products