Thermal processing and nutritional quality 271 Table 11.1 Composition of the primary fragmentation pools Type of pool Constituents Amino acid Amines fragmentation pool Carboxylic acids Kanes and aromatics Aldehydes Amino acid specific side chain fragments: H,S(Cys), CH,SH even Sugar fragmentation CI fragments: formaldehyde, formic acid pool (S) C2 fragments: glyoxal, glycoladehyde, acetic acid 3 fragments: glyceraldehyde, methylglyoxal, hydroxyacetone dihydroxyacetone, etc. C4 fragments: tetroses, 2, 3-butanedione, 1-hydroxy-2-butanone 2-hydroxybutanal, etc. C5 fras eoxy derivati C6 fragments: pyranone, furans, glucosone, deoxyglucosone Amadori and Heyns C3-ARP/HRP derivatives: glyceraldehyde-ARP, amino fragmentation pool acid-propanone, amino acid-propanal, etc IDI C4-ARP/HRP derivatives: amino acid-tetradiuloses amino acid-butanones C5-ARP/HRP derivatives: amino acid-pentadiuloses C6-ARP/HRP derivatives: amino acid-hexadiuloses, pyrylium betaines Lipid fragmentation Propanal, al hexanal, octanal. nonanal 2-Oxoaldeh C6-9) C2 fragments: glyoxal 3 fragments: CHOCH_CHO, methylglyoxal Amadori rearrangement(Fig. 11.6). These pyrroles and furans polymerise very easily to highly coloured compounds that may be involved in the formation of melanoidins By means of experiments showing that sugars and most amino acids also undergo independent degradation(Yaylayan and Keyhani, 1996), a new concep tual approach to the Mr has been proposed recently by Yaylayan(1997). He sug- gested that in order to understand the mr better. it is more useful to define a sugar fragmentation pool [S), an amino acid fragmentation pool (A], and an interaction fragmentation pool (D, deriving from the Amadori and Heyns com- pounds( Table 11. 1). Together they constitute a primary fragmentation pool of building blocks that react to give a secondary pool of interaction intermediates and eventually a very complex final pool of stable end-products G owever. most foods contain also lipids that can degrade by autoxidation rosch, 1987) giving reactive intermediates, mainly saturated or unsaturated aldehydes or ketones and also glyoxal and methylglyoxal (in common with theAmadori rearrangement (Fig. 11.6). These pyrroles and furans polymerise very easily to highly coloured compounds that may be involved in the formation of melanoidins. By means of experiments showing that sugars and most amino acids also undergo independent degradation (Yaylayan and Keyhani, 1996), a new concep￾tual approach to the MR has been proposed recently by Yaylayan (1997). He sug￾gested that in order to understand the MR better, it is more useful to define a sugar fragmentation pool {S}, an amino acid fragmentation pool {A}, and an interaction fragmentation pool {D}, deriving from the Amadori and Heyns com￾pounds (Table 11.1). Together they constitute a primary fragmentation pool of building blocks that react to give a secondary pool of interaction intermediates and eventually a very complex final pool of stable end-products. However, most foods contain also lipids that can degrade by autoxidation (Grosch, 1987) giving reactive intermediates, mainly saturated or unsaturated aldehydes or ketones and also glyoxal and methylglyoxal (in common with the Thermal processing and nutritional quality 271 Table 11.1 Composition of the primary fragmentation pools Type of pool Constituents Amino acid Amines fragmentation pool Carboxylic acids {A} Alkanes and aromatics Aldehydes Amino acid specific side chain fragments: H2S (Cys), CH3SH (Met), styrene (Phe) Sugar fragmentation C1 fragments: formaldehyde, formic acid pool {S} C2 fragments: glyoxal, glycoladehyde, acetic acid C3 fragments: glyceraldehyde, methylglyoxal, hydroxyacetone, dihydroxyacetone, etc. C4 fragments: tetroses, 2, 3-butanedione, 1-hydroxy-2-butanone, 2-hydroxybutanal, etc. C5 fragments: pentoses, pentuloses, deoxy derivatives, furanones, furans C6 fragments: pyranones, furans, glucosones, deoxyglucosones Amadori and Heyns C3-ARP/HRP derivatives: glyceraldehyde-ARP, amino fragmentation pool acid-propanone, amino acid-propanal, etc. {D} C4-ARP/HRP derivatives: amino acid-tetradiuloses, amino acid-butanones C5-ARP/HRP derivatives: amino acid-pentadiuloses C6-ARP/HRP derivatives: amino acid-hexadiuloses, pyrylium betaines Lipid fragmentation Propanal, pentanal, hexanal, octanal, nonanal pool {L} 2-Oxoaldehydes (C6–9) C2 fragments: glyoxal C3 fragments: CHOCH2CHO, methylglyoxal Formic acid, acids