Maillard Mixtures

Maillard mixtures are a complex set of chemical compounds resulting from reactions between amino acids and sugars in either aqueous or solid states. These products have complicated structures, and possess numerous functional groups (Kolb et al., 2005). The astrobiological significance of these mixtures has been revealed by the similarities between the solid-state C-13 NMR spectra of the solid Maillard mixtures and the insoluble organic material from Murchison meteorite (Kolb et al., 2005, 2006).

Like the amino acids, Maillard mixtures also rapidly cause polymerization of sodium silicate (Kolb and Liesch, 2006). However, unlike the amino acids, which produce whitish gels and colorless solutions, the Maillard mixtures ultimately result in brownish or black gels and solutions. These colored gels have a rubbery consistency, but like the amino acids gels, yield small white chunks and powder after being processed. Also, like the case of amino acids, sol-gel-sol transformations were observed in the gels from the Maillard mixtures. This strengthens the astrobiological relevance of the Maillard mixtures as the sol-gel-sol transformations could lead to the preservation and subsequent transport of these compounds.

Analysis of these processed and dried gels also revealed an overall lack of organics (Kolb and Liesch, 2006). It appears that the Maillard mixtures catalyze the polymerization of the sodium silicate solution. Some entombment may be occurring, but it appears that much of the entombed organic material is removed during the processing of these gels.

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