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Early indication of the Maillard reaction by analysis of reaction intermediates and volatile decomposition products.

Fruehzeitiger Nachweis der Maillard-Reaktion durch Bestimmung von Reaktions-Zwischenprodukten und fluechtigen Abbauprodukten
: Eichner, K.; Ciner-Doruk, M.

Progress in food and nutrition science 5 (1981), pp.115-135
ISSN: 0306-0632
Journal Article
Fraunhofer ILV ( IVV) ()
Abbau; Maillard-Reaktion; Nachweis; Produkt; Reaktion; Zwischenprodukt

For optimizing thermal processes like drying, where the Maillard reaction usually becomes dominant, an early detection of this reaction by applying analytical methods is desirable. In low moisture sugar-amino acid model systems and foods of plant origin it was shown, that the Maillard reaction is initiated with the formation of reducing intermediates (Amadori-rearrangement products of the sugar-amino acid reaction). No induction period in the formation of these intermediates could be observed, whereas visible browning is delayed, most greatly at lower water contents. Some of these intermediates proved to be rather heat stable, on account of which they can be used as indicators for the overall heat impact during processing. Their concentration can be set in relation with the quality and storage stability of the dried product. Using model systems containing different reducing sugars and amino acids or the corresponding Amadoriproducts it could be shown, that the overall browning rate is dependent on the greatly differing rate of formation and decomposition of different browning intermediates. However under certain conditions Amadori compounds cannot be regarded as real reaction intermediates attributed to a reaction pathway, which is proceeding directly from the labile 1,2 enaminol intermediate of the Amadori rearrangement. Using low moisture model systems of different composition it turned out, that in the presence of Amadori compounds volatile Strecker degradation products of amino acids detected by gas chromotography are formed at a higher rate, than if the corresponding reducing sugars and amino acids were present. The formation of volatile products as well as the formation of Amadori compounds and browning is greatly accelerated by increasing the water content. After reconstitution of dried plant foods like tomato powder and dried carrots with hot water Strecker degradation products and othervolatile compounds are formed at a higher rate, if higher amounts of Amadori compounds arising from heat impact during drying were present. Among the volatile products analyzed isovaleraldehyde, the Strecker degradation product of leucine, can be used for an early indication of sensoric changes attributed to the Maillard reaction, because it can be detected by head-space gas chromotography already in concentrations below the limit of sensoric perceptivity, whereas at higher concentrations there is a correlation with the extent of undesirable sensoric changes.