Post on 30-Jul-2020
complex of enzymatic and nonenzymatic reactions
carbonyl, anomers OH, primary OH, secondary OH
nonenzymatic browning reactions
reaction of saccharides
Maillard reaction
(reaction with proteins, amino acids)
caramelisation
Reactions of saccharides
reactants
reducing mono- and oligosaccharides
non-reducing oligo- and polysaccharides after hydrolysis
main reactions of monosaccharides
Reaction of saccharides themselves
cukerné alkoholy
anhydrocukryoligosacharidy
cukerné
kyselinyisomery
nižší cukry,
reduktony,
jiné fragmenty
ulosy
monosacharidmonosaccharides
oligosaccharides anhydrosugars
isomers sugar acids
uloses
sugar alcohols
reductons fragments
acid-basic catalysed reactions
in acid medium in alcali medium
(further factors: temperature, time)
mutarotation
formation (hydrolysis) of glycosides isomeration
dehydration rearrangement
reductone formation fragmentation
oxidation
formation and hydrolysis of glycosides
reaction of poloacetals OH
hydrolysis (inversion)
production of starch syrups
invert sugar
galactose
preferably (16) bonds, less (14) and other bonds
RR OH
HH2O-
monosacharid
O
OH
OH
HO
CH2OH
OH
O
OH
OH
HO
CH2OHO
OH
OH
HO
CH2OH
O H
H
glykosid (hetero- nebo homoglykosid)
karbeniový kation
O
OH
OH
HO
CH2OHO
OH
OH
HO
CH2OH
O
H
R
-HO
OH
OH
HO
CH2OH
O
+
+
+
+
++
formation (reverse, Fischer reaction)
side products of inversion (starch syrup: 5-6%)
side products of caramelisation
monosaccharide carbenium cation
glycoside (hetero- or homo glycoside)
mechanism of hydrolysis of saccharose
pH (5.2-5.8)
enzymatic hydrolysis, hydrolases, inactivation 80 oC
chemical hydrolysis, losses 0.5% /h
CH2OH
+
+
+
+
sacharosa
D-fruktosa D-glukosa
O
OH
OH
HO
CH2OH
OH
H
H-
H2O
O
OH
O
CH2OH
HO
OH
OH
O CH2
HOHO
O
OH
O
CH2OH
HO
OH
OH
O CH2
HO
CH2OH
HO
O
OH
CH2
CH2OHHO
HO
HOO
OH
CH2
CH2OH
HO
HO
H
pH 8.4
Ca(OH)2
Maillard reaction
saccharose
D-fructose D-glucose
glucose isomaltose -D-Glcp-(16)-D-Glcp 68-70%
(disaccharides) genciobiose -D-Glcp-(16)-D-Glcp 17-18%
maltose -D-Glcp-(14)-D-Glcp
cellobiose -D-Glcp-(14)-D-Glcp
saccharose kestose -D-Fruf-(26)--D-Fruf-(21)--D-Glcp
(trisaccharides) kelose -D-Fruf-(26)--D-Fruf-(21)--D-Glcp
low energy foods
indicators of adulteration
HO6
levanbiosa
1
2
1
2
CH2
OH
OO
CH2OH
CH2
OH
O
CH2OH
O
CH2OH
OH
HO
O
HO HO
HOsacharosa
kestose
saccharose
levanbiose
dehydration reaction
reaction of semiacetal OH and other OH
semiacetal OH / and other OH anhydrosugars (glycosans)
other OH / other OH deoxysugars
anhydrosugars
-D-Glcp 1,6-anhydro--D-Glcp (-glucosan)
-D-Manp 1,6-anhydro--D-Manp (-mannosan)
-D-Galp 1,6-anhydro--D-Galp (-galactosan)
ketoses dimeric anhydrides (tricyclic compounds)
formation
byproducts of inversion (glucose: 1%)
by-products of caramelization (higher amount)
1
6
HO
O
O H
O H
CH2O
2
1
O
O
HO
OH
CH2OHO
HO
CH2OH
OH
O
,1
,2
deoxysugars
1,2-enolisation (series of isomeration and dehydratation)
o
H2O-
C O
CH2
H
H OH
OH
CH2OH
C
C
CH O
3-deoxy-D-erythro-hexos-2-ulosa
3,4-dideoxy-D-glycero-hex-3-enos-2-ulosa
C
C
C
C
CH2OH
OH
H
H
O
H
CH O
H2O-
H2O-
O CHCH2HO O
5-hydroxymethylfuran-2-karbaldehyd
OHH
H
H
H
HO
OH
OH
OH
CH2OH
C
C
C
C
CC
C
C
C
C
CH2OH
O
OH
OH
OH
HO
H
H
H
H
H
D-glukosa 1-en-1,2-diolD-glucose
5-hydroxymethylfuran-2-carbaldehyde (HMF)
O CHCH2HO O
5-hydroxymethylfuran-2-karbaldehyd
D-glukosa
D-fruktosa
pentosy, L-askorbová kyselina
6-deoxyhexosy (methylpentosy)
2-hydroxyacetylfuran
O
CH2OHO
O CH O
5-methylfuran-2-karbaldehyd
furan-2-karbaldehyd
OCH3 CHO
o
D-glucose
D-fructose
pentoses, L-ascorbic acid
6-deoxyhexoses (methylpentoses)
5-hydroxymethylfuran-2-carbaldehyde (HMF)
2-hydroxyacetylfuran
furan-2-carbaldehyde
5-hydroxymethylfuran-2-carbaldehyde (HMF)
5-methylfuran-2-carbaldehyde
2,3-enolisation
C
C
C
C
CH2OH
O
OH
O
H
H
CH2
H
OHH2O-
1-deoxy-D-erythro-hexo-2,3-diulosa2-en-2,3-diol
C
C
C
C
CH2OH
OHH
H
CH2 OH
OH
OH
OH
D-fruktosa
C
C
C
C
CH2OH
CH2OH
O
OH
OH
HO H
H
H
CH3
C
C
O
O
C
C
CH2OH
OHH
OHH
C
C
C
C
CH3
CH2OH
O
OH
O
H
C
C
C
C
CH3
CH2OH
O
OH
O
H
H
O H
H2O- H2O-
O COCH3
OH
isomaltol
O
O
OH
CH3
maltolcaramel aroma
D-fructose
o
o
pentosy
hexosy
6-deoxyhexosy
(methylpentosy)
C
C
C
C
CH3
CH2OH
OH
OH
O
O
H
H
furaneol
CH=OH
O
OHO
CH2HO CH3
4-hydroxy-5-hydroxymethyl-2-methyl-(2 H)-furan-3-on
O
OHO
H3C
4-hydroxy-5-methyl-(2 H)-furan-3-on
O
OHO
CH3H3C
4-hydroxy-2,5-dimethyl-(2 H)-furan-3-on
o
norfuraneol
hexoses
pentoses
6-deoxyheoses (methylpentoses)
reductone formation
antioxidants
reduction of organic substances, metal ions
pH 6 monoanions
pH 6 dianions
1
2
1
2
C
C
C
R
R
OH
OH
O C
C
C
R
R
O
O
O
2 H
2 H
-
redukton triulosareductone triulose
isomeration
aldose ketose
aldose aldose (epimeration)
CH
C
C
C
C
CH2OH
O
OH
OH
OH
HO
H
H
H
H
D-glukosa
CH
C
C
C
C
CH2OH
O
OH
OH
HO
HO H
H
H
H
D-mannosa
D-fruktosa
HO
C
C
C
C
CH2OH
OH
OH
H
H
H
O
CH2OH
CH
C
C
C
C
CH2OH
OH
OH
OH
HO H
H
H
OH
1-en-1,2-diol
D-fructose
D-glucose D-mannose 1-en-1,2-diol
example
Glc / pH 10 /35 oC Glc 64%
Fru 31%
Man 3%
further isomerization - other aldoses and ketoses
disaccharides isomeration
lactose lactulose epilactose
-D-Galp-(14)-D-Glcp -D-Galp-(14)-D-Fruf -D-Galp-(14)-D-Manp
trioses isomerisation
C
CH O
CH2OH
HO H
L-glyceraldehyd
CH2OH
C
CH2OH
O
1,3-dihydroxyaceton
C
CH O
CH2OH
H OH
D-glyceraldehyd 1-en-1,2-diolát
C
CH
CH2OH
OH
OH
1-en-1,2-diolate
1,3-dihydroxyacetone
D-glyceraldehyde L-glyceraldehyde
rearrangement to acids
1-en-1,2-diol, Cannizzaro reaction, benzyl rearrengement
CH
C
C
C
C
CH2OH
O
OH
OH
OH
HO
H
H
H
H
D-glukosa
CH
C
C
C
C
CH2OH
OH
OH
OH
HO H
H
H
OH
1-en-1,2-diol
COOH
CHOH
CH2
C
C
CH2OH
H
H
OH
OH
CH2
C
C
CH2OH
H
H
OH
OH
COH(CH2OH)
COOH
CH2
C
C
CH2OH
H
H
OH
OH
COH(CH3)
COOH
metacukrové isocukrové cukrové
kyseliny
D-glucose 1-en-1,2-diol
meta sugar acids
sugar acids
iso sugar acids
+
+
C
CH O
OH
CH2
Cannizzarova
reakce
CH2OH
C
CH2OH
O
1,3-dihydroxyaceton
H
C
CH O
O
CH3
methylglyoxal
C
CH3
COOH
HHO
L-mléčná kyselina
C
CH3
COOH
OHH
D-mléčná kyselina
-
-
-eliminace
C
CH O
CH2OH
OHH
D-glyceraldehyd
H-
1-en-1,2-diolát
C
CH O
CH2OH
OH C
CH
CH2OH
OH
O
D-glyceraldehyde 1-en-1,2-diolate
1,3-dihydroxyacetone methylglyoxal
L-lactic acid D-lactic acid
Cannizzaro reaction
β-elimination
fragmentation
formation of reactive componds
retroaldolisation
R CH
OH
CH=O R CH CH C
R
CH=O
OH OH OH
aldolizace
retroaldolizace
aldolisation
retroaldolisation
glyoxal 2C hydroxyacetone 3C methylglyoxal 3C
1,3-dihydroxyacetone 3C laktaldehyde 3C hydroxymethylglyoxal 3C
CH
C
C
C
C
CH2OH
O
OH
OH
OH
HO
H
H
H
H
D-glukosa
C
C
C
C
CH2OH
OH
OH
HO
H
H
O
H
CH2OH
D-fruktosa1-en-1,2-diol
CH
C
C
C
C
CH2OH
OH
OH
HO
H
H
OH
H
OH
2-en-2,3-diol
C
C
C
C
CH2OH
OH
OH
HO
H
H
CH2OH
OH
CH2OH
CH O
glykolaldehyd
CH OH
formaldehydCH2OH
C
C
OH
OH
H
H
CH O
D-erythrosaCH2OH
C
C
C
OH
OH
H
H
HO H
CH O
D-arabinosa
CH O
C
CH2OH
OHH
D-glyceraldehyd D-glyceraldehyd
CH O
C
CH2OH
OHH C
CH2OH
CH2OH
O
1,3-dihydroxyaceton
CH O
C
CH2OH
OHH
D-glyceraldehyd
oxidadation (after isomeration, dehydration)
D-glyceraldehyde D-glyceraldehyde 1,3-dihydroxyacetone D-glyceraldehyde
D-glucose D-fructose
formaldehyde glycolaldehyde
D-erythrose D-arabinose
non-enzymatic browning reaction
reactants
sugars (carbonyl compounds)
monosaccharides and reducing oligosaccharides
(nonreducing oligosaccharides, polysaccharides, glycosides)
triose …. pentose hexose (acyclic form)
aldose ketose
-dikarbonyls aldehydes ketones saccharides
proteins (aminocompounds)
-NH2 Lys, N-ending NH2, guanidyl Arg, SH Cys
free amino acids, amines, ammonia
-NH2 …. -NH2 -NH2
NH3 R-NH2 aminoacid (reactivity is related to their basicity)
Maillard reaction
French pronunciation : [majaʁ], Engl.: /maɪˈjɑr/
Réaction générale des acides aminés sur les sucres. Journal de Physiologie, 1912 tome 14 page 813
reaction conditions
water activity (aw 0,3-0,7)
pH (5-9)
others (temperature, time of reaction, other components)
formation of cations
HX
HXX
-
X-
+
+
+
+
+
NH3 NH4
amoniak amonná sůl
R NH2 R NH3
primární amin sůl aminu
1 1 1
R
C O
R
R
C O H
R
R
C OH
R
H
karbonylová sloučenina
protonation of the carboxyl group increases its reactivity
protonation of the amino group reduces its reactivity
carbonyl compound
ammonia ammonium salt
primary amine salt of amine
concequences
positive, negative
• formation of aroma compounds
• formation of yelow, brown, black pigments melanoidins
+ bread crust, coffee, fried products
- dried foods (milk), fruits
• decrease of nutritive value reaction with Lys
• formation of potentially toxic products
reaction in vivo (glykosylation of proteins)
mechanism of reactions
3 stages
initial stage
formation of glykosylamines (Amadori rearrangement) and formation of aminodeoxysugars (Amadori products)
middle stage
decomposition of saccharides, glycosylamines, aminodeoxysugars (dehydratation, fragmentation)
decomposition of amino acids (Strecker degradation)
final stage
reaction of degradation products, formation of aroma, taste and colour products (melanoidins)
glycosylamines and aminodeoxysugars
totally utilisable form non-utilisable form
aldose aldosylamine ketosamine(1-amino-1-deoxyketose) Amadori rearrangement
ketose ketosylamine aldosamine (2-amino-2-deoxyaldose) Heyns rearrangement
O
CH2OH
OH
OH
HO
OH
O
CH2OH
OH
OH
HO
NH R
OH
CH2 NH RO
HO
OH
HO
D-glukosylamin D-fruktosamin
(1-amino-1-deoxy- D-fruktosa)
D-glukosa
adice
dehydratace
cyklizace
isomerace
(Amadoriho p.)
D-glucose D-glucosylamine D-fructosamine 1-amino-1-deoxy-D-fructose
addition dehydration cyclisation
isomeration (Amadori rearrangement)
mechanisms (reaction of acyclic forms)
H2O-R NH2
CH
C
C
C
C
CH2OH
OH
OH
OH
HO
H
H
H
H
O
D-glukosa karbinolamin
C
C
C
C
CH2OH
OH
OH
OH
HO
H
H
H
H
CHOH
NH R
imin (Schiffova báze)
C
C
C
C
CH2OH
OH
OH
OH
HO
H
H
H
H
CH
N R
O
CH2OH
OH
OH
HO
NH R
D-glukosylamin
O
CH2OH
OH
OH
HO
NH R
D-glukosylamin kation Schiffovy
báze
+
+
-C
C
C
C
CH2OH
OH
OH
OH
HO
H
H
H
H
CH
NH R
+
-
NH R
CH2
H
H
H
HO
OH
OH
CH2OH
C
C
C
C O
NH
CH
H
H
H
HO
OH
OH
OH
CH2OH
C
C
C
C
R
enolforma cyklická forma
H H
oxoformaD-fruktosamin (1-amino-1-deoxy- D-fruktosa)
OH
CH2 NH RO
HO
OH
HO
D-glucose D-glucosylamine
D-glucosylamine D-fructosamine (1-amino-1-deoxy-D-fructose) enol form oxo form cyclic form
carbinolamine imine (Schiff´s base)
cation of Schiff´s base
decomposition of aminodeoxysugars
1,2-enolisation acidic medium
2,3-enolisation neutral and alkaline medium
formation of glycosuloses and glycodiuloses (aldoketoses and diketoses)
o
1,2-enolisace
2,3-enolisace
produktyH H2O- H2O
H-
-R NH2
+
+
+ +
enaminol
C
CH
O
O
CH2
3-deoxy-D-erythro-hexos-2-ulosa
produktyH
+
+
+H-
-R NH2
1-deoxy-D-erythro-2,3-hexo-2,3-diulosa
CHO H
C OH
CH NHR
C H
C
CH
OH
NR
C
C
O
O
CH3
D-fruktosamin
CHO H
C
CH2
O
NHR
C H
C
CH NHR
OH
H2O
C
C OH
O
CH2
C
C OH
OH
CH2 NH2R
endiol
CHO
C OH
CH NHRR
R R R R
R R R R
(HMF,…)
(HMF,…)
2,3-enolisation
1,2-enolisation
D-fructosamine
products (HMF, …)
products (HMF, …)
3-deoxy-D-erythro-hexos-2-ulose
1-deoxy-D-erythro-2,3-hexo-2,3-diulose
analogy with the reactions of sugars themselves
lower activation energy
unlike reactions of carbohydrates themselves these are running already at ambient temperatures and pH 4-7
products contain N and S
qualitatively and quantitatively more products
in parallel - decomposition of sugars and aminoacids themselves
examples
formation of methylglyoxal and 2,5-dimethylpyrazine
from fructosamine
NH R
CH2
H
H
H
HO
OH
OH
CH2OH
C
C
C
C O
D-fruktosamin
CH2OH
NH R
CH2
C O
CH=O
H OH
CH2OH
C
aminoanalog
1,3-dihydroxyacetonu
D-glyceraldehyd
CH=O
C O
CH3
methylglyoxal
CH
C O
CH3
N R
H2O
H2O
R NH2
imin
methylglyoxalu
retroaldolizaceretroaldolisation
D-fructosamine 1-amino-1-deoxy-D-fructose
D-glyceraldehyde methylglyoxal
imine of methylglyoxal
amino analogue of 1,3-dihydroxyacetone
R = H
(Strecker´s degradation of amino acids)
formation of 2,5-dimethylpyrazine
aroma of roasted nuts, potato chips
CH
C O
CH3
NH
C
CH3
OH
CH NH2
C
CH3
OH
CH NH2 C
CH3
HO
CHNH2
+
N
N
H
H
CH3
CH3- 2 H2O
oxidace
N
N
CH3
CH3
2,5-dimethylpyrazino
2,5-dimethylpyrazine
important heterocyclic products
isomaltol furaneol furfurylthiol caramel strawberries, pineapple coffee
maltol 2,4-dimethylthiophene 2-acetyl-1-pyrroline 2,6-dimethylpyrazine caramel fried onion bread chocolate, roasted nuts
O
OH
CH3
O
O
HO
CH3 CH3
O
O CH2 SH
O
O
OH
CH3 S
CH3
CH3 NCH3
O
N
N
CH3CH3
Maillard reaction in important food commodities
positive and negative consequences
desirable and undesirable reactions
technology (aroma, taste, colour, nutritive value)
roasting
cooking, baking, frying
drying
extrusion, microvawe heating
milk, milk products
Lys losses: 10-30% traditional drying, 3% sprey drying
cereals, cereal products
Lys losses: 70% bread crust, 10% total
meat, meat products
mutagenes (heterocyclic amines)
fruits, vegetables
coffee, cocoa, nuts
reactions in the processing of milk unavailable (blocked) Lys
isomeration lactose lactulose + epilactose
lysinoalanin
-N-deoxylaktulosyllysin)
R
H2O2+
HOH2C
NH
CH
C
HN
O
HCl
NH
CH
C
HN
CH
CO
O
protein
furosin
OO
C CH2 NH
CH3
HO
pyridosin
NO
[CH2]4 CH COOH
NH2
NHCH2
C
C
CH2
C
CH2OH
OHH
O
O
[CH2]4 CH COOH
NH2
[CH2]4 CH COOH
NH2
[CH2]4
O
OH
OH
OH
NHCH2
OC
OH
H
H
H
HO C
C
C
CH2OH
O
[CH2]4
laktosa
OH
O
OH
OH
CH2OH
O
OH
OH
OHO
CH2OH
NH2
1-lysino-1-deoxylaktulosalactose
inhibition of Maillard reaction
creating unfavorable conditions
water content (activity), lower temperature, regulation of pH
removal of one reaction partner
use of inhibitors
SO2 + H2O H2SO3 H+ + HSO3-
CH=O
CH OH
HSO3- CHOH
CH OH
SO3-
sulfonová kyselinaaldehyd
o
aldehyde sulfonic acid
sugars
sugars (saccharose, glucose, fructose, starch sirup, invert sugar
temperature
150-190 oC (240 oC)
reaction time
5-10 h
catalysts
caramel = solid product
couler = liquid product
Caramelisation
class name of couler additives matter utilisation
I CP caustic Na2CO3, K2CO3, NaOH, KOH, H2SO4, acetic acid, citric acid
alcoholic beverages (high content of alcohol)
II CCS caustic sulphite SO2, H2SO4, Na2SO3, K2SO3, NaOH, KOH,
vinegar, beer, alcoholic beverages, aromatised wine
III AC ammonium NH3, (NH4)2SO4, Na2CO3, H2SO4, NaOH, KOH
beer, alcoholic beverages, acid food
IV SAC ammonium-sulphite
NH3, SO2, (NH4)2SO3, Na2SO3, K2SO3, Na2CO3, K2CO3, NaOH, KOH, H2SO4,
acid food, non-alcoholic beverages