31st fnk europe conference on potato processing - recent ... · 2,3-enolisation aldohexose furans...
TRANSCRIPT
Imre Blank
Nestec Ltd., Nestlé Research Centre, P.O. Box 44,Vers-chez-les-Blanc, 1000-Lausanne 26, Switzerland
31st FNK Europe Conference on Potato Processing- Recent Developments in the Maillard Reaction -
• Conceptual representation of the Maillard reaction
• Reactive intermediates
• Formation of flavour
• Formation of colour
• Analytical aspects
Recent developments in the Maillard reaction- Structure of the presentation -
• Conceptual representation of the Maillard reaction
• Reactive intermediates
• Formation of flavour
• Formation of colour
• Analytical aspects
A conceptual approach in the classificationof the Maillard reaction
Pathways of the Maillard reaction
AMADORI PRODUCT
Aldose sugar +Amino compound
Fission productsFurfural or HMF Reductones
Dehydroreductones
CO2
Aldols, N-free polymers
+ Amino acid
Strecker degradation
Aldimines, ketimines
MELANOIDINSWith or withoutamino compound
+ Aminocompound
ALDEHYDES
+ Aminocompound
- 2H + 2H
pH < 7- Amino compound- water
pH > 7
- Water
+ Aminocompound
N-substitutedglycosylamine
+
+ Aminocompound
EARLY
ADVANCED
Initial phase of the Maillard reaction
(Hodge, 1953;Isbell & Frush, 1958;Mauron, 1981)
Aldohexose Amino acid
Schiff base
Amadori compound(Aminoketose)
Aldosylamine
Advanced phase of the Maillard reaction- Degradation of Amadori compounds -
(Hodge, 1953; Anet, 1958; Mauron, 1981)
Amadori compound(Aminoketose)
3-Deoxy-2-hexosulose
1,2-Enolisation2,3-Enolisation
Aldohexose
Furans (HMF) Furanones (Furaneol) Melanoidins
1-Deoxy-2,3-hexodiulose Aminodiketose
Initial phase of the Maillard reaction
(Hodge, 1953; Mauron, 1981)
Generation of ‘primary fragmentation pools’from the components of the ‘parent pool’
(V. Yaylayan, Trends Food Sci. Technol., 8, 13, 1997)
Amadori and Heyn’s products
Amino acids Reducing sugars
{D}
{S}{A}
Primary fragmentation pools
Principal precursors
Composition of ‘primary fragmentation pools’
Amino acid fragmentation pool {A}:Amino acids, amines, carboxylic acids, amino acid-specific side-chain fragments (methylsulfide from methionine, styrene from phenylalanine)
Sugar fragmentation pool {S}:C1 fragments (formaldehyde, formic acid)C2 fragments (glyoxal, glycolaldehyde, acetic acid)C3 fragments (glyceraldehyde, pyruvaldehyde, hydroxyacetone, …)C4 fragments (tetroses, diacetyl, hydroxybutanone, …)C5 fragments (pentoses, pentuloses, deoxy derivatives, furanones, furans, ...)C6 fragments (pyranones, furans, glucosones, deoxyglucosones, …)
Amadori and Heyn’s fragmentation pool {D}:C3-C6 ARP/HRP derivatives
Genealogy of ‘self-interaction pools’ and‘secondary interaction pools’ from ‘primary
interaction pools’
(V. Yaylayan, Trends Food Sci. Technol., 8, 13, 1997)
Some examples for compounds formed in the‘interaction pools’
• Self-interaction pools: {S x S}, {A x A}, {D x D} e.g. early polymers, dimers, aldol condensation products
• Secondary interaction pools: {A x S}, {S x D}, {A x D} e.g. Strecker aldehydes, α-amino carbonyls {A x S}, e.g. di-sugar ARP/HRP {S x D}, e.g. maltoxazine and quinoxalinones {A x D},
• Multiple-interaction pools: e.g. late polymers
Some elementary processes occurring in the‘interaction pools’
• Aldol condensation: chain elongation simple carbonyls, α-hydroxy carbonyls
• Retro aldol reaction: chain-cleavage processes
• Reduction by formic acid: imine → amine, aldehyde → alcohol
• Redox reactions: disproportionation, cyclisation/decomposition
• Carbonyl group migration
• Other processes: β-elimination, cyclisation, dimerisation, polymerisation, ...
Conceptual representation of the Maillard reaction- The formation and interaction of ‘chemical pools’
-Polymers
Heterocycles Dimers
Other
(V. Yaylayan, Trends Food Sci. Technol., 8, 13, 1997)
Role of the Maillard reaction in food
Sensory propertiesDevelopment of appealing flavour and colourOff-flavour formation, undesired browning
Quality and safetyFood preservationLoss of nutritional value
Formation mechanism of the Amadori compoundDFG from glucose and glycine
(H+)
OH
OH
OHOH
O
OHO
OH
OH
HOHO O
OH
OH
HOHO NH
H2N COOHCOOH
NH COOH (H+)OH
OH
OH
HOHO NH COOH
(H+)
(Hodge, 1955; Isbell & Frush, 1958; Paulsen & Pflughaupt, 1980; Westphal & Kroh, 1985)
4C1-β-D-Glucose N-Glucosylglycine
2C5-β-DFG Eneaminol
Mechanism of the decompositionof Amadori compounds
(Hodge, 1953; Anet, 1964; Simon & Heubach, 1965)
H2C-NHR
C = O
HO-C-H
H-C-OH
H-C-OH
CH2OH
HC-NHR
C-OH
HO-C-H
H-C-OH
H2C-NHR
C-OH
C-OH
H-C-OH
HC=NHR
C-OH
C-H
H-C-OH
+
CH2C-OH
C = O
H-C-OH
HC = O
C = O
CH2H-C-OH
CH3C = O
C = O
H-C-OH
H2O- OH-
- H2NR
O
OHO
OOH
CHO
1,2-Eneaminol 3-Deoxy-2-hexosulose HMF
2,3-Enediol 1-Deoxy-2,3-hexodiulose Furaneol
DFG
Study on the Formation and Decompositionof Amadori Compounds in Maillard Model Systems
• Conceptual representation of the Maillard reaction
• Reactive intermediates
• Formation of flavour
• Formation of colour
• Analytical aspects
Pathways of the Maillard reaction(Hodge, 1953)
AMADORI PRODUCT
Aldose sugar +Amino compound
Fission productsFurfural or HMF Reductones
Dehydroreductones
CO2
Aldols, N-free polymers
+ Amino acid
Strecker degradation
Aldimines, ketimines
MELANOIDINSWith or withoutamino compound
+ Aminocompound
ALDEHYDES
+ Aminocompound
- 2H + 2H
pH < 7- Amino compound- water
pH > 7
- Water
+ Aminocompound
N-substitutedglycosylamine
+
+ Aminocompound
EARLY
ADVANCED
Role of N-(1-deoxy-D-fructos-1-yl)-glycine (DFG)in the nonenzymatic browning reaction
• Formation of DFG from glucose and glycine• Thermal-induced decomposition of DFG• Formation of flavour (Furaneol)
OH
OH
OH
OH
Hexose
N
OH
OH
OH
O
OH
OH
Amadori compound
GlycineOHOH
O
O
O OH
3(2H)-FuranoneGluose N-(1-Deoxy-D-fructos-1-yl)-glycine
(DFG)Furaneol
Occurrence:
Liver (hog) Borsook et al., 1955Apricot, peach (freeze-dried) Anet & Reynolds, 1957Molasses (sugar beet) Carruthers et al., 1963Soy sauce Hashiba, 1978Meat (roasted), tomato powder van den Ouweland, 1978Malt, beer Wittmann & Eichner, 1989Cocoa (roasted) Heinzler & Eichner, 1991
Concentration:
10-70 mg/kg (malt) Wittmann & Eichner, 198930-60 mg/kg (cocoa) Heinzler & Eichner, 1991
DFG is a stable intermediate formed during theMaillard reaction of glycine and glucose or mannose
Formation of the Amadori compound DFG1 M aqueous solution of glucose and glycine, pH= const., T= 90 °C
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
0 20 40 60 80 100 120Time ( min )
DFG
( m
ol )
pH 6pH 7
Initial phase of the Maillard reaction
Hodge, 1953;Isbell & Frush, 1958;Mauron, 1981
Aldohexose Amino acid
Schiff base
Amadori compound(Aminoketose)
Aldosylamine
Decomposition of the Amadori compound DFG1 M aqueous solution, no buffer, pH= const., T= 90 °C
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100 120Time ( min )
DFG
( m
ol )
pH 6pH 7
Advanced phase of the Maillard reaction- via the Amadori compound -
Hodge, 1953; Anet, 1958; Mauron, 1981
1-Deoxy-2,3-hexodiulose
Amadori compound(Aminoketose)
3-Deoxy-2-hexosulose
Aminodiketose
1,2-Enolisation2,3-Enolisation
Aldohexose
Furans (HMF) Furanones (Furaneol) Melanoidins
O
OHO
FuraneolConcentration: 1-10 mg/kgFlavour note: Caramel-like, sweetThreshold: 0.1 mg/L water ; 1 ng/L air
Furaneol contributes to the overall flavourof many thermally processed foods
Occurrence: Beef (boiled) Tonsbeek et al., 1968Coffee (roasted) Tressl et al., 1978Cocoa (roasted) Ziegleder, 1991Bread crust (wheat, rye) Schieberle, 1992Beef (roasted) Cerny & Grosch, 1992Sesame seeds (roasted) Schieberle, 1993Meat flavours (commercial) Blank et al., 1994French fries Wagner & Grosch, 1997
Formation of furaneol from the Amadori compound DFG1 M aqueous solutions, no buffer, pH= const., T= 90 °C
0
20
40
60
80
100
120
140
160
180
200
15 30 60 120Time ( min )
Fura
neol
( m
g / m
ol )
pH 6.0pH 7.0
Formation of furaneol from glucose and glycine1 M aqueous solutions, no buffer, pH= const., T= 90 °C
0
5
10
15
20
25
30
15 30 60 120Time ( min )
Fur
aneo
l ( m
g / m
ol )
pH 6.0pH 7.0
O
O OH
O
OH O
OHc
b
1-Deoxy2,3-hexodiulose
Acetylformoine
N
OH
OH
OH
O
OH
OOH
R
H
N-(1-Deoxy-D-fructose-1-yl)-glycine (DFG)
a
O
OH OH
OH
- Amino acid
H
O
O
OH
OH
OH O
OH
OH
O- H2O
- H2O
OHOOO
(Blank et al., 6th Maillard Symp. London, 1997)
Schematic formation of furaneol from the Amadoricompound DFG via acetylformoine
Summary
favoured at pH 7compared to pH 6
Maillard model systems:
• Composed of the Amadori compound DFG or its precursors glucose and glycine
• Heated in unbuffered aqueous solutions at 90 °C over 2 hours under pH control
Results:
• Formation of the Amadori compound DFG• Decomposition of DFG• Generation of Furaneol from DFG
(J. E. Hodge & B. E. Fisher,Meth. Carbohydr. Chem. 2, 99, 1963)
Glycine
OH
OH
OHOH
ONH
OHO
OH
OH
HOHO
Na2S2O5
Amberlite / H+
OH
OH
OHOH
ONH
COOH
COOH
H2N-CH2-COOHNa2S2O5 / H2O
Amberlite / H+�
�
4C1-β-D-Glucose DFG (β-pyranose, 2C5)
13C-DFG
Synthesis of N-(1-deoxy-D-fructos-1-yl)-glycine (DFG)and 13C-DFG used as labelled internal standard
Synthesis of 13C-labelled furaneol: internal standard forquantification by isotope dilution assay (IDA)
OBocBocO
OBocBocO
O
O
O
H
O
OHO
O
OOH
�
�
�
�
��
�
�
O O
1. LIDA2. 13CH3
13CHO
3. (t-BuOCO)2O, THF
KMnO4acetone/H2O/HOAc
Oxalic acid/H2O
(I. Blank et al., J. Agric. Food Chem. 45, 2642, 1997)
Quantification of furaneol by isotope dilution assayusing 13C2-furaneol as internal standard in GC-MS
100000
150000
10000
20000
30000
50000
8.00 10.00 11.00
Furaneol
13 C -2 FuraneolO
OHO
O
OOH
��
�
�
9.00
O
OHO
O
OOHm/z 128
m/z 130
Time (min)
(I. Blank et al., J. Agric. Food Chem. 45, 2642, 1997)