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.

1. Introduction

Norwegian University of Life Sciences 2Christina Steppeler

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1. Introduction

Christina Steppeler

2. Mechanisms

• Ferrous ion (Fe2+) in porphyrin

• Prostetic group of proteins

– Catalase, nitric oxide synthase– Cytochrom– Hemoglobin, myoglobin

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-Heme-

Bastide et al. (2011) Cancer Prev Res: 4(2),177-84

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Bastide et al. (2011) Cancer Prev Res: 4(2),177-84

2. Mechanisms

-Heme-

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• 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

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© 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

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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© Charles River Laboratories 

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APCMin/+ mouse model

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• Regulation

• Apoptosis ↑• Proliferation ↓• Differentiation ↑• Migration↑

APC expression

mig

rati

on

© Johns Hopkins Colon Cancer Center (modified)

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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???

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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

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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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• 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

Thank you for your attention!

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Digestive fluids