Proline-specific Maillard products

Amino acid specific Maillard products were isolated from the extracts by preparative GC or HPLC and identified by MS-, IR-, 1 H- and c-NMR-spectroscopy. Proline derived components are important constituents in bread, malt and beer. More than 120 proline specific Maillard products were characterized. Cysteine and methionine derived components were predominant in roasted coffee and meat flavors. Thirty cysteine- and twenty methionine-specific Maillard products were identified for the first time. 

Helak B., Spengler K., Tressl R. and Rewicki D. (1989a) Formation of 7//-cyclopenta[6]pyridin-7-ones as proline-specific Maillard products. J. Agric. Food Chem. 37, 400-4. 

Dihydro-IH-pyrrolizines are as proline specific Maillard products <85MI 801-01). 

Tressl, R. Helak, B. Martin, N. Rewicki, D. Formation of proline specific Maillard products. In Amino-carbonyl Reaction in Food and Bioloflcal Systems Fujimaki, M. Namiki, M. Kato, H., Eds. Elsevier-Kodansha Tokyo, 1986 pp 235-244. 

Proline is the second most abundant amino acid (13-18%) contained in wheat gluten, and plays a very in rtant role in flavor formation during food processing. A great deal of work has been carried out by Tressl et aL (5) on the volatile conponents generated in proline-specific Maillard reactions. The most abundant proline-specific Maillard reaction products arc 2,3-dihydro-IH-pyrrolizines. 

Tressl, R. Helak, B. Kersten, E. Formation of proline and hydroxyproline-specific Maillard products from [l- C]glucose. J. Agric. Food Chem. 1993, 41, 547-553. 

Sugar degradation products were determined as benzimidazole derivatives after reaction with o-phenylenediamine. More than 120 amino-acid specific Maillard products have been isolated and identified from the reaction of L-proline, hydixn roline, < teine and methionine with monosaccharides at 150° for 1-1.5 h, in connection with studies of thermally generated aromas. Proline derived components were important constituents of bread, malt and beer, and cysteine and methionine derived components were predominant in roasted coffee and meat flavours. The effects of temperature, pH, and the relative concentration of rhamnose and proline on the quantity of specific volatiles produced in the Maillard reaction of these substrates have been studied, and the data have been analysed 1 computer methodology. The glucosylated cyclopentenone (44) was one of the products of decomposition of the Amadori product 1-deoxy-l-piperidino-maltulose in warm water. ... 

Nutritional Effects Due to the Presence of the Maillard Products. Many physiological or antinutritional effects have been attributed to the Maillard products. Specific effects have been attributed to the Amadori products deoxyfructosylphenylalanine (a model substance not likely to be present in large quantities in foods) appears to depress the rate of protein synthesis in chicks (32) and to partially inhibit in vitro and in vivo the absorption of tryptophan in rats (33). The compound e-deoxyfructosyllysine inhibits the intestinal absorption of threonine, proline, and glycine and induces cytomegaly of the tubular cells of the rat kidneys (34) as does lysinoalanine. In parenteral nutrition the infusion of the various Amadori compounds formed during sterilization of the amino acid mixture with glucose is associated with milk dehydration in infants and excessive excretion of zinc and other trace metals in both infants and adults (35,36,37). 

Some Amino Add-Specific Compounds. As listed in Table I, there were three pyrrolizines and one pyridoimidazole identified in the model systems. Pyrrolizines are a very in rtant class of volatile conpounds generated by the reaction of proline with reducing sugars. 2-Acetyl-pyrido(3,4-d)imidazole was another amino acid-specific Maillard reaction product identified in the model systems, which was derived fi om the reaction of histidine with dicaibonyls. 

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