Über den Chemismus der Huminsäurebildung unter physiologischen Bedingungen, V. Mitteil.: Die einleitende Phase der Huminsäurebildung: Eine Aldolkondensation von Methylglyoxal

Abstract

E n d e r s , S i g u r d s s o n : Uber den[Tahm. 76 Curt E n d e r s und S i g u r d u r S i g . u r d s s o n : Uber denChemismus der Huminsaurebildung unter physiologischen Bedingungen, V. Mitteil. *): Die einleitende Phase der Huminsaurebildung : Eine Aldolkondensation von Methylglyoxal. [-4us d. Techn. Hochschule u. d. Wissenschaftl. Station fur Brauerei in hIiinchen.]

Dehydrated Foods, Chemistry of Browning Reactions in Model Systems

“…Glucose-glycine melanoidin was considered to occupy an intermediate position between the two extremes represented by furfural and pyruvaldehyde melanoidins. The melanoidins derived from acetaldehydeglycine or pyruvic acid-glycine gave colors in incident ultraviolet light which are different from that of the firstnamed group, indicating possible differences in structure (45). In unpublished work, Carson and Olcott found that the melanoidins which are produced from acetaldehyde and amino compounds are not acidic, contrary to the case with sugar-amine melanoidins.…”

“…Browning, of whatever type, is caused by the formation of unsaturated, colored polymers of varying composition (33,39, 41, 45,46,82,96,180,197). Compounds that engender browning usually contain a carbonyl or potential carbonyl grouping.…”

“…Three acidic glucose-glycine reaction products (neither crystalline nor homogeneous) were isolated in low yields by elution of the reaction mixture (concentrated aqueous solution heated at 45 °C., pH 5) from an anion-exchange column by Barnes and Kennedy (10). Determinations of carbon, hydrogen, and molecular weight gave: (a) C8Hi708N -1.5H20, (b) [C8H1708N -2H20]2.…”

“…Because of the similarity in composition and properties of the melanoidins derived from the reaction of glycine with glucose, mannose, xylose, furfural, or pyruvaldehyde, it has been assumed that all were derived from similar intermediates (39,45,179,197). Traitteur ( 183) has now reported significant differences among furfural-glycine melanoidin (high content of ether-bound oxygen), glucose-glycine melanoidin (high content of alcoholic hydroxyl groups), and pyruvaldehyde-glycine melanoidin (high content of enolic hydroxyl groups and low content of ether-bound oxygen).…”

Evolution of Concepts of Environmental Natural Nonliving Organic Matter

“…Enders and Sigurdsson (1944) found this equilibrium to be pH -and temperature -dependent under test tube conditions. Enders and Sigurdsson (1943) postulated a pathway from methylglyoxal to acetaldehyde (via pyruvic acid) and acetaldehyde could polymerize via the aldol condensation mechanism. In order to show how HAs could be formed under physiological conditions, Enders (1943b) postulated that methylglyoxal could be released by soil microorganisms under conditions unfavorable for microbial growth (lack of substrate, low or high temperature, etc.)…”