browning in thermally processed foods: the maillard reaction
DESCRIPTION
BROWNING IN THERMALLY PROCESSED FOODS: THE MAILLARD REACTION. Food modifications during thermal treatment (1). Protein denaturation Physical changes (starch gelatinization, structural alterations of cell wall, depolymerization of dietary fibre ) Lipid oxidation - PowerPoint PPT PresentationTRANSCRIPT
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BROWNING IN THERMALLY PROCESSED FOODS: THE MAILLARD
REACTION
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Food modifications during thermal treatment (1)
• Protein denaturation• Physical changes (starch
gelatinization, structural alterations of cell wall, depolymerization of dietary fibre)
• Lipid oxidation• Degradation of some bioactive
components
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Food modifications during thermal treatment (2)
• Reaction between different components generate new compounds.
• Proteins-sugar: Maillard reaction formation of Advanced Glycosilation End-products (AGEs)
• Lipid-protein: Advanced lipoxidation end products (ALEs)
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The same chemistryThe reaction is in both cases (sugars or oxidised lipids) between a carbonyl moiety and an amino group
The same products
The final product of both reaction patways (AGEs and ALEs) are polymeric brown macromolecules
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The Maillard Reaction in Foods
Produces aromas in heated foods
Responsible for colour formation (non-enzymatic browning)
Maillard products have antioxidant properties
•Can cause loss of nutrients
•Some products may be toxic
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LATTE UHT
LATTE STERILIZZATO
BIRRA CHIARA
PASTA
PRODOTTI DA FORNO
BIRRA SCURACACAO
CARNE ARROSTITA
CAFFE’
Stadi iniziali
Stadi intermedi
Stadi avanzati
Tem
pera
tura
e te
mpo
di t
ratt
amen
to te
rmic
oD
iminuzione dell’attività dell’acqua
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Louis-Camille Maillard(1878 - 1936)
Photographed in his laboratory
ca 19151912 – 1916: He published 8 papers on his
observations of colour changes on mixing amino acids
and sugars.
No one else took much interest in the reaction until 1950s
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Maillard-Hodge Reaction?
John Hodge: 1914 -1996 • Chemist at USDA in Illinois (1941 – 1980)
• His proposed mechanism for the chemistry of non-enzymic browning is largely unchanged after 60 years.
Citations since 1970
Paper Citations
Hodge, J. E.Chemistry of browning reactions in model systems.J. Agric. Food Chem. 1953, 1: 928-943.
890
Maillard, L. C.Action des acides amines sur les sucres: formation des melanoidines par voie methodique.Compt. Rend. 1912, 154: 66-68.
634
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Hodge Scheme
Hodge J E. Dehydrated foods: chemistry of browning reactions in model systems. J. Agric. Food Chem. 1:928-43, 1953.
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First step: formation of Amadori product
RNH
HC
(HCOH)n
HC
CH2OH
O
GlicosilamminaN-sostituita
+H+
RNH
CH
(HCOH)n
HCOH
CH2OH
+
Catione dellabase di Schiff
-H+
RNH
CH
COH
(HCOH)n
CH2OH
Forma enolicadel PA
RNH
CH2
CO
(HCOH)n
CH2OH
1-ammino-1-deossi-2-chetoso (PRA)
PRODOTTO DIAMADORI
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slow
fast
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Formation of Carbonyl through Maillard Reaction
OH
OH
OH
OH
NH
R2,3-enolisation
OH
OH
OH
O
NH
R
OH
OH
OH
OH
NH
R
1,2-enolisation
Amadori compound
O
O
OH
OH
O
O
O
OHO
O
O
O
O
1-deoxyosone
RNH2 H2O
- H2O
H2O
OH
OHO
O
O CHO
3-deoxyosone
OH
OHOH
NH
R +
H2O
RNH2
H +
slow
fast
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Strecker Degradation
Free amino acids with dicarbonyl compounds
R-CHO
Aldeide di Strecker
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Flavour and Colour in the Maillard Reaction
H2O
rearrangement
NHROH
OOH
H
OH
OH
Amadori intermediate
carbonyl compounds
H2O RNH2
O
O
H
O
O
O CHOHO
O
OOH
O OH
OO CHO
O OH
O
amino acids
FLAVOUR COMPOUNDS
MELANOIDIN PIGMENTS
H
O
OH OH
OHOH
OH
R NH2+
reducing sugar aminocompound
Amino acid or
proteins
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General scheme of MR browning
Amine AmmoniaPhospholipidsAmino acidsProteins
CarbonylAldehydesKetonesReducing sugarsPolysaccharidesOxidised lipids
Amino CarbonylInteraction
(Amadori product)HEAT
MelanoidinsBrown colour
AmidesAcrylamide
Furans, Pyrroles,Thiopenes, Thiazoles,Oxazoles, Imidazoles,Pyridines, Pyrazines
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N
R
CHO
R
O
RN
HOO
O OH
CH3N
HO
OH
CH3
O
R
N
N+
H2N
N
NN
O
R
H
R
NN
NN
NN
O
O
O
O
O
O
O R'
R' R'
R'
R'
R
NN
NN
N
O
O
O
O
O R' R'
R'
R'
Protein A
Protein B
LysineN
NN
NN
NN
NN
N
O
O
O
O
O
O
O
O
O
O R'
R'
R'
R'
R' R'
H
H
H
H
H
H
H
H
H
H
Food “melanoproteins”
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Pronyl-lysine
This compound is formed on the lateral
chain of Lysine residues
Pronyl-lysine has a high antioxidant activity
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Possible toxicants
• Acrylamide
• Furan
• Heterocyclic amines
• 3-MPCD (Mono Chloro Propan Diol)
• 3-Methyl Imidazolone
Development of mitigation strategies to reduce their concentration
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A network of many reactions giving thousands of products
Products formed depends on:
•Chemical nature of the reactants
•Time and temperature of heating
•Technological conditions
•Water activity, pH
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Practice
Effects of reactants:
Sodium Carbonate (pH effects)
Protein and carbohydrates
Water activity (fibre addition)
Butter clarification
Control
Added with sodium bicarbonate