44. Degradation of α-amino-acids to aldehydes and ketones by interaction with carbonyl compounds

Effects of melamine on the Maillard reaction between lactose and phenylalanine

“…The first stage is initiated by the covalent attachment of reducing sugars to the N-terminal amino groups, resulting in the formation of reversible and unstable imines (or glycosylamine) which subsequently transform to Amadori rearrangement products. Subsequently, Amadori products undergo several reactions including dehydration, deamination, retroaldol and aldol reactions, enolizaiton and Strecker degradation to form Maillard intermediates containing many kinds of reactive carbonyl species (RCS), a-aminoketones, Strecker aldehydes and others (Hidalgo, Gallardo, & Zamora, 2005;Hofmann & Schieberle, 2000;Namiki, 1988;Schonberg, Moubasher, & Mostafa, 1948;Weenen, 1998). At the final stage of the reaction, the intermediates would involve in all kinds of dehydration, cyclisation and polymerisation reactions resulting in the formation of complicated Maillard reaction products composed of browning ingredients, volatile or flavour compounds (Schebor, Buera, Karel, & Chirife, 1999;van Boekel, 2006).…”

Role of Amino Acids in the Browning of Orange Juice

“…Degradat,ion of amino acids by oxidized ascorbic acid to aldehydes, carbon dioxide and ammonia was reported by Abderhaldeii (1-3) to occur at p H 7 a t 37" C. and Schonberg et al (38) showed that unsubstituted a-amino acids undergo the Strecker degradation on heating with dehydroascorbic acid with the evolution of COn and formation of aldehydes. On the other hand, ascorbic acid is known to react with alloxan and ninhydrin a t p H 7.2 and 30" C. to give dehydroascorbic acid which then loses COZ and is converted to L-xylosone (33).…”

Studies on the Strecker Degradation of Alanine with Glyoxal

“…The decarboxylation step in Strecker degradation is considered to be an important one, since the production of carbon dioxide proceeds juts before the formation of aldehyde, a potential contributor to food flavor, and the generated quantities of these two products were considered to be equal as proposed by Shonberg. 18) The aldehyde, a reactive species which may also react with amino acids or with compounds produced in the amino-carbonyl reaction, is difficult to be determined in exact quantity. From that point of view, to study the decarboxylation is useful way for the elucidation of the mechanism of aldehyde production.…”