Browning Reactions 9Maillard browning reducing sugar + amine brown pigments + flavors 9Caramelization sugar brown pigments + flavors high temps 9Enzymatic browning phenolics brown pigments + flavors polyphenoloxidase
Browning Reactions 9Maillard browning reducing sugar + amine brown pigments + flavors 9Caramelization sugar brown pigments + flavors high temps 9Enzymatic browning phenolics brown pigments + flavors polyphenoloxidase
Caramelization 9 At high temperatures, sugar reactions are accelerated – Isomerization – Water elimination – Oxidation no amines 9 Caramelization occurs at – High temperatures (~150˚C) – Low water content/high sugar Caramel flavors and pigments 9 Formation of – Enediols – Dicarbonyls
Caramelization 9 At high temperatures, sugar reactions are accelerated – Isomerization – Water elimination – Oxidation no amines 9 Caramelization occurs at – High temperatures (~150˚C) – Low water content/high sugar Caramel flavors and pigments 9 Formation of – Enediols – Dicarbonyls
Dehydration mechanism C C C C C C HO OH H 2OH OH OH H H H H - OH C C C C C C H 2O - OH H 2OH OH OH H H H H - O H H + + C C C C C C OH H 2OH - OH OH H H H H = O H 2O, H + 1. dehydration (elimination) 2. isomerization enediol C C C C C C - OH H 2OH H - H - - H H = O = O H - - OH dicarbonyl H new resonance, isomerization
Dehydration mechanism C C C C C C HO OH H 2OH OH OH H H H H - OH C C C C C C H 2O - OH H 2OH OH OH H H H H - O H H + + C C C C C C OH H 2OH - OH OH H H H H = O H 2O, H + 1. dehydration (elimination) 2. isomerization enediol C C C C C C - OH H 2OH H - H - - H H = O = O H - - OH dicarbonyl H new resonance, isomerization
Caramelization: Consequences 9 Leads to nice flavors and colors in many foods – Caramel aroma, coffee – Beverage colors, beer – Maltol one important flavor (produced by Maillard rxns also) 9 Can also lead to undesirable flavors and colors – “burnt-sugar” smell O OH CH 3 O
Caramelization: Consequences 9 Leads to nice flavors and colors in many foods – Caramel aroma, coffee – Beverage colors, beer – Maltol one important flavor (produced by Maillard rxns also) 9 Can also lead to undesirable flavors and colors – “burnt-sugar” smell O OH CH 3 O
Maillard Reaction
Maillard Reaction