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Formation of malondialdehyde (MDA) during in vitro digestion of cooked beef, pork, chicken and salmon.C. Steppeler1,2, R. Rødbotten2 and B. Kirkhus2 1Norwegian School of Veterinary Science, Norwegian University of Life Sciences, NMBU, Oslo, 5 Norway. 6 2Nofima, Norwegian Institute of Food, Fisheries and Aquaculture Research, Ås, Norway.
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1. Introduction
Norwegian University of Life Sciences 2Christina Steppeler
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Norwegian University of Life Sciences 3
1. Introduction
Christina Steppeler
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2. Mechanisms
• Ferrous ion (Fe2+) in porphyrin
• Prostetic group of proteins
– Catalase, nitric oxide synthase– Cytochrom– Hemoglobin, myoglobin
Norwegian University of Life Sciences 4
-Heme-
Bastide et al. (2011) Cancer Prev Res: 4(2),177-84
Christina Steppeler
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Norwegian University of Life Sciences 5
Bastide et al. (2011) Cancer Prev Res: 4(2),177-84
2. Mechanisms
-Heme-
Christina Steppeler
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Christina Steppeler Norwegian University of Life Sciences 6
• minced• Vaccum-packed• 70 °C, 50 min
Oral
Phase
• Simulated saliva fluid, pH 7
Gastric
Phase
• Simulated gastric fluid, pH 3• pepsin• 120 min, 37 °C
IntestinalPhase
• Simulated intestinal fluid, pH 7• pancreatin, bile• 80 min, 37 °C
TBARS
3. In vitro digestion
meat/fish
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TBARS
©2013 R&D Systems, Inc.
TBARS – Thiobarbituric reactiv substancesTBA – Thiobarbituric acidMDA – Malondialdehyde
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Lipid peroxidation
Adapted from: Gardner, H.W., in Xenobiotics in Foods and Feeds, J.M. Finley and D.E. Schwass, Editors. 1983, Am. Chem. Soc.: Washington D.C. p. 63-84.
• Heme (metals)• Fat content• Fatty acid composition• Antioxidants• Salt• pH• Oxygen availability• Protein digestibility • Oxidation products present
before digestion
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Characterisation of meat
Fat(%)
DBNitrite
(mg/kg)Iron
(mg/kg)PV
(mekv/kg fat)
Minced beef 8.9 (10.0*) 52.3 <0.16 20.0 <0.1
Minced pork 6.4 (9.0*) 76.9 <0.16 9.7 <0.1
Minced chicken 8.5 (9.5*) 113.6 <0.16 7.2 <0.1
Salmon loins 11.4 (14.0*) 149.7 <0.16 3.2 <0.1
3. In vitro digestion
Christina Steppeler
© www.cartoonwallpaper.net & iStockphoto
*Declared by producer
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GP IP0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
MD
A (
µmol
/kg
mea
t)
Undigested GP IP0
2
4
6
8
10
12
14
16
18
20
Before homogenization After homogenization
MD
A (
µm
ol/k
g m
eat)
3. In vitro digestion
Blank samples Minced beef
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3. In vitro digestion
minced chicken
salmon minced beef
minced pork
0
50
100
150
200
250
300
350
A
Undigested GP IP
MD
A (
µm
ol/k
g m
eat)
minced chicken
salmon minced beef
minced pork
0
500
1000
1500
2000
2500
3000
B
Undigested GP IP
MD
A (
µm
ol/k
g fa
t)
113.6
149.7
76.952.3
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4. Feeding experiment
• Heterozygous germline mutation
• Tumorsuppressor gene:
Adenomatous polyposis coli
• Familiar adenomatous polyposis (FAP)
• Mutations in 80 % of sporadic colorectal cancer
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Norwegian University of Life Sciences 12
© Charles River Laboratories
Christina Steppeler
APCMin/+ mouse model
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• Regulation
• Apoptosis ↑• Proliferation ↓• Differentiation ↑• Migration↑
APC expression
mig
rati
on
© Johns Hopkins Colon Cancer Center (modified)
Christina Steppeler
4. Feeding experimentAPCMin/+ mouse model
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Diets• 10 energy% fat• 10 energy% fat + hemin• 45 energy% fat• 45 energy% fat + hemin
Endpoints???
Christina Steppeler
4. Feeding experimentAPCMin/+ mouse model
Low in Ca, Vit D3, fiber. Fat source: beef tallow. Diets isocaloric.
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Small flat aberant crypt foci
Large flat aberant crypt foci
AdenomasPaulsen et al. (2005) Cancer Res: 65,121-129
Picture: Marianne Sundt Sødring
Norwegian University of Life Sciences
4. Feeding experiment
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Animals weighed
birth
0-3
weaned; assigned
to diet 1-4
8
termination
Collection feces (2x fresh + 2x 24h-feces)
4. Feeding experimentTime course
4
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Christina Steppeler
• Food intake (isocaloric diet)
• Feacal dry matter
• Caecum: Microbiota
• Fresh feces: SCFA
• 24h-feces (2 days): Bile salts, TBARS, heme
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4. Feeding experiment
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Thank you for your attention!
Norwegian University of Life SciencesProject Presentation – Christina Steppeler 18
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Digestive fluids