Maillard reaction is important for aroma, taste, and color in foods like roasted coffee beans, baked bread, and cooked meats. It involves a condensation reaction between reducing sugars and amino acids to form glycosylamine compounds, which then undergo rearrangement and further reactions depending on pH. In acidic conditions, these reactions form compounds like furfurals responsible for roasted flavors, while in basic conditions they form reductones and other products that contribute to toasted and caramelized aromas through additional reactions with amino acids.

1. Maillard reaction is related to aroma, taste and colour, in cooking like roasting of coffee and
cocoa beans, baking of bread and cakes, toasting of cereals and cooking of meat.
In early stage, sugar-amine condensation withareducingsugar(glucose) andamines( aminoacids)
reactionto forman N-substitutedglycosylamine.
N-substitutedglycosylamine undergoesAmadori rearrangement, toformketosamine( Amadori
compound )
The furtherreactionof Amadori productdependsonthe pH of the system.
In acidicpH (lessthan7), itforms1,2 enolisationtoformfurfurals(incase of pentoses) or
hydromethylfurfural (incase of hexose).

2. In basicpH (above 7),2,3 enolisationoccurstoform reductones (enediolswithacarbonyl group
adjacentto the enediol group,)like4-hydroxy-5methyl-2,3dihydrofuram-3-one orfuraneol (2,5-
Dimethyl-4-hydroxy-furan-3-one) ,anda varietyof fissionproductslikeacetol (hydroxyacetone),
pyruvaldehyde anddiacetyl form.
inbasic pH, fission productslike acetol,pyruvaldehyde anddiacetyl alsoforms.

3. The dicarbonyl compoundscanfurtherreactwithaminoacids to formaldehydesandα aminoketones
by Streckerdegradation.
A wide range of streckeraldehydesare formedwithdistinctaromas.
Amino acid (R) Strecker aldehyde formed(R) odour
Valine
2 methyl propanal Greenoverripe fruit
Leucine
3 methyl butanal
Malty toastedfruitybread
Isoleucine
2 methyl butanal Fruitysweetroasted
phenylalanine
phenylacetaldehyde Greenfloral hyacinth
Methionine Methional Vegetablelikearomas
Cysteine Mercaptoaldehyde, Meat like aroma
https://slideplayer.com/slide/10420918/
https://www.brewersjournal.ca/2017/05/18/science-malliard-reaction/
but pyrrole reactsina differentmannerwithaldehydes,toform1-pyrroline andpyrrolidines. These are
importantintermediatesinbreadlike aromas.