technologically significant reactions (oleochemistry) 1 ... lipid reactions.pdf · technologically...
TRANSCRIPT
![Page 1: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/1.jpg)
LIPID REACTIONS
Technologically significant reactions (oleochemistry)
1. esterification
enzymatic (lipases)
nonenzymatic (acid and base catalysis)
1.1.esterifications
20-100 °C, H2SO4, HCl
R-OH + R1-COOH R1-COOR + H2O
glycols, alditols + FA emulsifiers
glycerol + FA (hydroxyl acids) emulsifiers (MAG and DAG)
![Page 2: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/2.jpg)
1.2. interesterification
acidolysis
R1-COOR + R2-COOH R2-COOR + R1-COOH
without catalyst, 250-300 °C; catalyst H2SO4, 150-170 °C
TAG + abietic acid varnish
TAG + phthalic acid glyptals
(drying oil – similar to natural resins)
exchange lower/higher FA coconut oil, palm kernel fat
enzymatically using lipase - synthesis of "structured TAG“
CBE fat (Cocoa Butter Equivalent) = POSt + StOSt
abietic acid derived from lat.
word Abies = fir;
nonvolatile
component of
turpentine
![Page 3: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/3.jpg)
alcoholysis
R1-COOR + R2-OH R1-COOR2+ R-OH
NaOH, NaOR 20 °C and more, H2SO4 ~ 100 °C, without catalyst 250 °C,
enzymatically by lipases
methanolysis Me-esters, biodiesel
butanolysis Bu-esters (plasts softenings)
glycerolysis parcial esters (emulsifiers)
transesterification
R1-COOR + R2-COOR3 R1-COOR3 + R2-COOR
without catalyst ~ 250 °C, acidic, basic catalyst 100 °C, enz. lipases
in the resulting mixture the distribution of FA in TAG is accidental
– randomisation (melting point higher for about 20 °C)
![Page 4: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/4.jpg)
2. molecule splitting - hydrolysis and saponification
R1-COOR R1-COOH + R-OH
autocatalysed hydrolysis at high temperatures over 200 °C
saponification by hydroxides soaps
3. hydrogenation
-CH=CH- -CH2-CH2-
H2, 150-200 °C, Ni-catalyst; 0,1-0,2 MPa
hardened fats (hardening, hydrogenation)
stability against oxidation, consistency, absence of trans-acids
![Page 5: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/5.jpg)
k1 k2 selective (dienic from trienic, rape oil)
k1 k2 nonselective
side-reactions
positional isomerisation (unusual isomers)
cis/trans isomerisation (30-45% trans-isomers)
9
12
12 9
12
9
12 91011 13
13 11
10
13 1110
13 11
10
k2k1 kyselina stearová
21R CH2 CH2 CH2 CH2 CH2 R
21
R CH CH CH2 CH CH R
kyselina linolová
kyselina 12-oktadecenová
21R CH CH CH2 CH2 CH2 R
kyselina olejová
21R CH2 CH2 CH2 CH CH R
H2H2
12- octadecenoic acid
oleic acid
linoleic acid stearic acid
![Page 6: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/6.jpg)
Rancidity of oils and fats hydrolytic rancidity
scented rancidity
reversion
oxidation
hydrolytic rancidity
enzymatic reactions: lipases (butter, coconut oil, palm oil)
chemical reaction: frying
TAG FA + DAG + MAG
butter, milk, coconut oil, palm oil undesirable
chocolate partly desirable
cheese desirable
![Page 7: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/7.jpg)
threshold value (mg/kg) of free fatty acids
FA cream coconut fat
smell taste smell taste
C4:0 rancid 50 60 35 160
C6:0 rancid 85 105 25 50
C8:0 moldy, rancid, soapy 200 120 1000 25
C10:0 soapy 400 90 1000 15
C12:0 soapy 400 130 1000 35
C14:0 soapy 400 400 1000 75
![Page 8: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/8.jpg)
flavor of polyunsaturated fatty acids in emulsions
(taste of the corresponding TAG is neutral)
FA threshold value mol/l taste
oleic 9-12 bitter, spicy
linoleic 4-6 bitter, spicy
elaidic 22 weakly spicy
-linolenic 3-6 weakly spicy
-linolenic 0.6-1.2 weakly spicy
arachidonic 6-8 weakly spicy
![Page 9: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/9.jpg)
scented rancidity
enzymatic reaction: microorganisms and their enzymes
FA with short and medium carbon chain
milk fat, coconut oil, palm oil undesirable
mould cheeses desirable
TAG R CH2 CH2 COOH R C
O
CH2 C
O
SCoA
HSCoA
R C
O
CH2 COOH
CO2
R C
O
CH3R CH
OH
CH3
R C
O
SCoACH3 C
O
SCoA
-oxokyselina methylketon
lipasa thiohydrolasa -ketothiolasa
dekarboxylasa oxidoreduktasa
β-oxo acid methyl ketone
lipase
oxidoreductase decarboxylase
thiohydrolase β-ketothiolase
![Page 10: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/10.jpg)
methylketon smell threshold value
g/kg (in water)
pentan-2-on fruity (bananas) 2300
hexan-2-on fruity (bananas) 930
heptan-2-on flowery, herbal 650
octan-2-on flowery 190
nonan-2-on flowery, meaty 190
![Page 11: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/11.jpg)
reversion
typical for soybean oil (or other oil containing linolenic acid )
chemical r. (autoxidation) hydroperoxides derivatives of furan
off-flavour:
the smell of varnish, fish, grass, beans
refining can remove odor, but the defect returns reversion
OC5
![Page 12: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/12.jpg)
OXIDATIVE RANCIDITY
oxidation of the hydrocarbon chains
nonenzymatic reactions
atmospheric oxygen (triplet/ 3O2) autoxidation
reactive oxygen species (singlet/1O2,radicals, H2O2)
5 excited states 1 (sigma) 1 (délta)
157 kJ 93,8 kJ
formation in food: photochemical reactions with the participation of photosensitizers from 3O2
pigments (riboflavin, chlorophyll, heme)
free radicals
O2- (superoxide radical)
OH (hydroxyl radical)
enzymatic reactions
lipoxygenases (formerly lipoxidases)
![Page 13: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/13.jpg)
consequences
negative lowering of sensory quality fats, oils, foods cosmetics, gasoline lowering of nutritive value reaction of oxidised lipids with proteins lowering of hygiene-toxicological quality toxic products aging, illness (in vivo)
positive formation of aromatic compounds
![Page 14: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/14.jpg)
nonenzymatic reactions oxidation by triplet oxygen, autoxidation general mechanism of hydrocarbon chain autoxidation (radical reaction)
1. induction stage
R-H R + H hydrocarbon radical
iniciators, homolytic decomposition
1. propagation stage
R + O2 R-O-O hydroperoxyl radical
R-O-O + R-H R-O-O-H + R hydroperoxide up to thousands of segments (influence temperature, pO2 etc.)
hydroperoxide= primary oxidation product decomposition of hydroperoxides
3. terminal stage
mutual radical reactions, polymers of various types
R + R R-R C-C bond
R + R-O-O R-O-O-R C-O-O-C bond (peroxide)
2 R-O-O R-O-O-R + O2
![Page 15: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/15.jpg)
initiation
mainly fotosensitized (photo-oxidation) and enzymatic reactions
singlet oxygen
hydroperoxide
„first radicals“ from hydroperoxide decomposition
hydroperoxide decomposition
monomolecular decomposition R-O-O-H R-O + OH alkoxyl radical
bimolecular decomposition (at higher concentrations of ROOH)
2 R-O-O-H R-O-O + R-O + H2O
reactivity of radicals
HO R-O R-O-O
subsequent fate of alkoxyl radicals
decomposition aromatic compounds
recombination in terminal stage
R + R-O R-O-R bond C-O-C
R-O + R-O-O R-O-R + O2
![Page 16: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/16.jpg)
oxidation of unsaturated acids (at ordinary temperature)
O : L : LL = 1 : 10 : 100
structure dissociation energy (kJ / mol) H-CH2- 422 CH3-CH-H- 410 -H-CH-CH=CH- 322 -CH=-CH-H-CH-CH=CH- 272
oxidation of unsaturated acids ambient temperature oxidation of saturated acids temperatures of frying and roasting
![Page 17: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/17.jpg)
oxidation of oleic acid mixture of 4 hydroperoxides in ratio of cca 1:1:1:1
geometric isomers cis or trans positional isomers - mainly trans
11-hydroperoxy-9-enová k.
89
8-hydroperoxy-9-enová k.
CH2 CH CH CH
O OH
910
CH CH CH CH2
O OH
9-hydroperoxy-10-enová k.
CH CH CH CH2
10-hydroperoxy-8-enová k.
CH2 CH CH CH
CH CHCHCH2
CH2 CH CH CH2
CH CH CH
O OH
CH2
CH CH CH CH2
CH CH CH
O OH
CH2
11 8
11
11
11
11
11
11
11
1110
10
10
10
10
10
10
10
9
9
9
9
99
9
8
8
8
8
8
8
8
.
..
.
11-hydroperoxy-9-enoic acid 8-hydroperoxy-9-enoic acid
9-hydroperoxy-10-enoic acid 10-hydroperoxy-8-enoic acid
![Page 18: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/18.jpg)
oxidation of linoleic acid mixture of 7 hydroperoxides, mostly 9- and 13-
oxidation of linolenic acid mixture of many hydroperoxides – mostly 9-, 12-, 13- and 16- with 2 conjugated double bonds and one isolated bond
. CH CH CH CH CH CH2CH2CH CH CH CH CH CH2CH2
volné radikály s konjugovanými dvojnými vazbami
910
9
9
9
10
10 10
11
11 11
12
12 1213
13
13 .
..
O OH
CH CH CH CH CH CH2CH2
(E,Z)-9-hydroperoxy-10,12-dienová k.
CH CH CH CH CH CH2CH2
O OH
(Z,E)-13-hydroperoxy-9,11-dienová k.
volný radikál s izolovanými
dvojnými vazbami
(mesomerní stav = pentadienový radikál)
CH CH CH CH CH CH2CH2
-
CH CH CH2 CHCH2 CH CH2
linolová kyselina
910111213 910111213
13 12 11
Hlinoleic acid
(E,Z)-9-hydroperoxy-10,12-dienoic acid (Z,E)-13-hydroperoxy-9,11-dienoic acid
free radicals with conjugated double bonds
free radical with isolated double bonds
![Page 19: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/19.jpg)
subsequent reaction of hydroperoxides
secondary autooxidation products
same number of C atoms epoxy-, hydroxy-, oxo-acids
lower number aldehydes, hydrocarbons and others
higher number various polymers
![Page 20: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/20.jpg)
formation of epoxy-, hydroxy- a oxo-compounds
CH2CH CHCH CH
O O R
CH CH
O
R O O R O- ... CH2 CH2
epoxykyselina
CH CH CH
O OH
CH CH CH
O
OH
CH CH CH
OH
CH CH C
O
hydroxykyselina
oxokyselina
epoxykyselina
CH CHCH
O
H
H-
epoxy acid
hydroxy acid
oxo acid
epoxy acid
![Page 21: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/21.jpg)
formation of aldehydes and hydrocarbons
volatile secondary products - flavour compounds general mechanisms
alkoxylový radikál
R-H
-
1 2
R1 2
R CH CH CH
O OH hydroperoxid
R CH CH
R CH CH2
RCHO+
R CH2 CH O
HO
11
+
oxokyselina aldehyd
aldehyd uhlovodík
2
OH
mastná kyselina hydroxykyselina
-
1
12
RR CH CH CH
O
R CH CH CH O2
R
2R
1
hydroperoxide
alkoxyl radical
hydroxy acid fatty acid hydrocarbon aldehyde
aldehyde oxo acid
![Page 22: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/22.jpg)
for example 9-hydroperoxy-10,12-fatty acid from linoleic acid
9-oxononanoic octanoic
(E,Z)-deca-2,4-dienal
(Z)-non-3-enal
subsequent reaction of aldehydes
CH CH2
O
CH2
CH3
CH CH CH
O
CH CH CH
O
aldehyd
HHO. .
.....
..
CHO
CH2 CH O
CH CH OH
CH CH
CH CH CH
O OH
mastná
kyselina
aldehyd
oxokyselina
++
O
CHCHCH CH2
hydroperoxidCH2
alkoxylový radikál
hydroperoxide
alkoxyl radical
aldehyde
oxo acid
aldehyde
fatty acid
![Page 23: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/23.jpg)
some of aldehydes arising by oxidation of unsaturated acids
primary aldehyde aldehyde after isomeration
hydroperoxy acid
(Z)-undec-2-enal (E)-2-undecenal (Z)-8-hydroperoxyoctadec-9-enoic (E)-dec-2-enal (E)-9-hydroperoxyoctadec-10-enoic nonanal (E)-10-hydroperoxyoctadec-8-enoic octanal (Z)-11-hydroperoxyoctadec-9-enoic (Z,Z)-undeca-2,5-dienal (E,E)-undeca-2,4-dienal (Z,Z)-8-hydroperoxyoctadeca-9,12-dienoic (E,Z)-deca-2,4-dienal (E,E)-deca-2,4-dienal (E,Z)-9-hydroperoxyoctadeca-10,12-dienoic (Z)-non-3-enal (E)-non-2-enal (E,Z)-10-hydroperoxyoctadeca-8,12-dienoic (Z)-okte-2-nal (E)-okt-2-enal (Z,Z)-11-hydroperoxyoctadeca-9,12-dienoic (E)-hept-2-enal (Z,E)-12-hydroperoxyoctadeca-9,13-dienoic hexanal (Z,E)-13-hydroperoxyoctadeca-9,11-dienoic pentanal (Z,Z)-14-hydroperoxyoctadeca-9,12-dienoic (E,Z,Z)-deca-2,4,7-trienal (E,Z,Z)-9-hydroperoxyoctadeca-10,12,15-trienoic (Z,Z)-nona-3,6-dienal (E,Z)-nona-2,6-dienal (E,Z,Z)-10-hydroperoxyoctadeca-8,12,15-trienoic
(Z,Z)-octa-2,5-dienal (E,E)-octa-2,4-dienal (Z,Z,Z)-11-hydroperoxyoctadeca-9,12,15-trienoic (E,Z)-hepta-2,4-dienal (E,E)-hepta-2,4-dienal (Z,E,Z)-12-hydroperoxyoctadeca-9,13,15-trienoic
(Z)-hex-3-enal (E)-hexe-2-nal (Z,E,Z)-13-hydroperoxyoctadeca-9,11,15-trienoic
(Z)-pent-2-enal (E)-pent-2-enal (Z,Z,Z)-14-hydroperoxyoctadeca-9,12,15-trienoic
propanal (Z,Z,E)-16-hydroperoxyoctadeca-9,12,14-trienoic
![Page 24: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/24.jpg)
organoleptic properties of aldehydes
aldehyde smell precursor propanal pungent linolenoic acid pentanal pungent linoleic acid hexanal tallowish, grass linoleic acid heptanal oily, greasy oleic acid nonanal tallowish linolenoic acid (E)-pent-2-enal oily, greasy, grass linolenoic acid (Z)-hex-3-enal Grass linolenoic acid (E)-hex-2-enal oily, greasy, grass linolenoic acid (E)-hept-2-enal oily, greasy linoleic acid (Z)-okt-2-enal after walnuts linoleic acid (E)-okt-2-enal oily, greasy linoleic acid (E)-non-2-enal oily, greasy linoleic acid (E,Z)-hepta-2,4-dienal oily, greasy,
after frying fats linolenoic acid
(E,E)-hepta-2,4-dienal oily, greasy linolenoic acid (Z,Z)-nona-3,6-dienal after cucumber linolenoic acid (E,Z)-nona-2,6-dienal after cucumber linolenoic acid (E,Z)-deca-2,4-dienal after frying fats linoleic acid (E,E)-deca-2,4-dienal after frying fats linoleic acid (E,Z,Z)-deca-2,4,7-trienal after fish oil linolenoic acid
![Page 25: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/25.jpg)
polymers formation usually by reaction of two radicals
C-C bonds ether bonds peroxide bonds
two-fold C-C bond tetrahydrofurane C-C and peroxide cyclopentane cycle bonds bonds
two-fold bond C-C tetrahydropyrane dioxane bonds cyclohexenic cycle bonds
OO
O
O
O
O
O O O
![Page 26: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/26.jpg)
oxidation with singlet oxygen
formation
photooxidation (photosensitizers)
enzymatic reaction (photosynthesis)
addition to the double bond, ~ 1000 x faster than oxidation
S1
**
R-H
R-O-OHhydroperoxid
S
S S
h
1 3
senzibilizátor
excitovaný singletový
senzibilizátor
excitovaný tripletový
senzibilizátor
singletový
kyslík
typ I typ II
R-H- R
S-H
radikál redukovaného
senzibilizátoru
O23
O23
O21
O2--
S+
kation
senzibilizátoru
-
excited singlet sensitizer
excited triplet sensitizer
sensitizer
hydroperoxide
singlet oxygen cation of a sensitizer
radical of reduced sensitizer
![Page 27: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/27.jpg)
scavengers of singlet oxygen and hydroxyl radicals
- can quench singlet oxygen
-carotene and other carotenoides
tocopherols
ascorbic acid
1 carotenoid + 1O2 3 carotenoid + 3O2
3 carotenoid (excited triplet state) 1 carotenoid
![Page 28: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/28.jpg)
enzymatic oxidation lipoxygenases (lipoxidases, linoleate: O2 oxidoreductase) E18:2 = 17 kJ/mol unsaturated FA hydroperoxide of UFA (optically active)
C18:2 9- a 13-hydroperoxides 10-hydroperoxides C18:3 9- a 13-hydroperoxides 10-hydroperoxides specifity (regio-, stereo-) example C18:2 soya (13S)-, 9-cis-, 11-trans- tomatoes (9S)-, 10-trans-, 12-cis mushrooms (10S)-, 8-trans-, 12-cis-
O O H
5 6 7 8 9 10
12 9
CH2 CH CH CH2 CH CH
![Page 29: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/29.jpg)
negative, positive consequences animals: decomposition by glutathionperoxidases plants and mushrooms: splitting by lyases, isomerases, aroma compounds
13-OOH-9,11,15- ~ (Z)-hex-3-enal grass (green) flavour
(Z)-hex-3-enal (E)-hex-2-enal leaf aldehyde
oily, greasy, green smell
9-OOH-10,12,15- ~ (Z)-non-2-enal oily smell
10-OOH-8,12- ~ (R)-okt-1-en-3-ol mushroom-like smell
C H 3 C H O
isomerace
C H3C H Olyasy
lyasyCH3
CH2
O H
![Page 30: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/30.jpg)
termic reactions
geometric isomerization cis/trans
positional isomerization
cyclization C18:1
C18:2
polymerization
Diels-Alder reaction
R1 R2
R1 R2
R1 R2
R1 R2
R1 R2
R3 R4
R1 R2
R3 R4
+
dimerC18:1
C18:2
![Page 31: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/31.jpg)
inhibition of autoxidation
temperature
air (oxygen)
radiation (UV)
composition of the fat (ratio of SFA/UFA)
inhibitors (antioxidants, synergists)
antioxidants
classification according to origin
natural (mostly tokopherols, phenols)
synthetic (mostly phenols)
classification according to activity (mechanisms)
primary (reaction with radicals)
secondary (reduction of R-O-OH)
![Page 32: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/32.jpg)
phenolic antioxidants (mechanism of action) R-O-O + H-A R-O-O-H + A
H-A (antioxidant) A● (antioxidant radical)
main reactions 2A A-A A + R-O-O R-O-O-A A + R-O R-O-A
side reactions ( 0,01%) A + O2 A-O-O A-O-O + R-H A-O-O-H + R
OH
RR
R
O
RR
R
.
![Page 33: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/33.jpg)
main natural antioxidants tocopherols gallates main synthetic antioxidants nebo
BHT BHA (cca 9 : 1) TBHQ
applications
BHA, BHT, tocopherols, dodecylgallate type of emulsion: oil/water
TBHQ, propygallate pure fats (oils)
O
HO
R
CH3
OH
OHHO
COOR
OH
CH3
OH
OCH3
OH
OCH3
OH
OH
![Page 34: Technologically significant reactions (oleochemistry) 1 ... Lipid reactions.pdf · Technologically significant reactions (oleochemistry) 1. esterification enzymatic (lipases) nonenzymatic](https://reader030.vdocuments.mx/reader030/viewer/2022011812/5e2feb446f37c2179904a2f9/html5/thumbnails/34.jpg)
antioxidant effect on the process of autoxidation reactions
P - peroxide number
t – time of autoxidation at 60oC (days)
1 - antioxidant BHA = 0% 2 – BHA=0,02%
I1 a I2 = induction periods protective factor PF = (I2-I1)/I1
0
20
40
60
80
100
0 2 4 6 8 10
P
t
1 2
I1 I2
PF, lard, 0,02%
-tocopherol 5
BHT 6
-tocopherol 15
BHA + BHT 12
BHA 9.5
octylgallate 6