Formation of malondialdehyde (MDA) during in vitro digestion of cooked beef, pork, chicken and salmon. C. Steppeler 1,2, R. Rødbotten 2 and B. Kirkhus 2 1 Norwegian School of Veterinary Science, Norwegian University of Life Sciences, NMBU, Oslo, 5 Norway. 6 2 Nofima, Norwegian Institute of Food, Fisheries and Aquaculture Research, Ås, Norway.

1. Introduction Norwegian University of Life Sciences2Christina Steppeler

Norwegian University of Life Sciences3 1. Introduction Christina Steppeler

2. Mechanisms Ferrous ion (Fe2+) in porphyrin Prostetic group of proteins –Catalase, nitric oxide synthase –Cytochrom –Hemoglobin, myoglobin Norwegian University of Life Sciences4 -Heme- Bastide et al. (2011) Cancer Prev Res: 4(2), Christina Steppeler

Norwegian University of Life Sciences5 Bastide et al. (2011) Cancer Prev Res: 4(2), Mechanisms -Heme- Christina Steppeler

Norwegian University of Life SciencesChristina Steppeler6 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 Intestinal Phase Simulated intestinal fluid, pH 7 pancreatin, bile 80 min, 37 °C TBARS 3. In vitro digestion meat/fish

Norwegian University of Life SciencesChristina Steppeler7 TBARS ©2013 R&D Systems, Inc. TBARS – Thiobarbituric reactiv substances TBA – Thiobarbituric acid MDA – Malondialdehyde

Norwegian University of Life SciencesChristina Steppeler8 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 Heme (metals) Fat content Fatty acid composition Antioxidants Salt pH Oxygen availability Protein digestibility Oxidation products present before digestion

Norwegian University of Life Sciences9 Characterisation of meat Fat (%) DB Nitrite (mg/kg) Iron (mg/kg) PV (mekv/kg fat) Minced beef8.9 (10.0*) 52.3 < <0.1 Minced pork6.4 (9.0*) 76.9 < <0.1 Minced chicken8.5 (9.5*) < <0.1 Salmon loins11.4 (14.0*) < < In vitro digestion Christina Steppeler © & iStockphoto *Declared by producer

Norwegian University of Life SciencesChristina Steppeler10 3. In vitro digestion Blank samples Minced beef

Norwegian University of Life SciencesChristina Steppeler11 3. In vitro digestion

4. Feeding experiment Heterozygous germline mutation Tumorsuppressor gene: Adenomatous polyposis coli Familiar adenomatous polyposis (FAP) Mutations in 80 % of sporadic colorectal cancer Christina Steppeler - 12 Norwegian University of Life Sciences12 © Charles River Laboratories Christina Steppeler APCMin/+ mouse model

Norwegian University of Life Sciences 13 Regulation Apoptosis ↑ Proliferation ↓ Differentiation ↑ Migration↑ APC expression migration © Johns Hopkins Colon Cancer Center (modified) Christina Steppeler 4. Feeding experiment APCMin/+ mouse model

Norwegian University of Life Sciences14 Diets 10 energy% fat 10 energy% fat + hemin 45 energy% fat 45 energy% fat + hemin Endpoints ??? Christina Steppeler 4. Feeding experiment APCMin/+ mouse model Low in Ca, Vit D3, fiber. Fat source: beef tallow. Diets isocaloric.

15 Small flat aberant crypt foci Large flat aberant crypt foci Adenomas Paulsen et al. (2005) Cancer Res: 65, Picture: Marianne Sundt Sødring Norwegian University of Life Sciences 4. Feeding experiment

Norwegian University of Life SciencesChristina Steppeler16 Animals weighed birth 0 -3 weaned; assigned to diet termination Collection feces (2x fresh + 2x 24h-feces) 4. Feeding experiment Time course 4

Food intake (isocaloric diet) Feacal dry matter Caecum: Microbiota Fresh feces: SCFA 24h-feces (2 days): Bile salts, TBARS, heme Norwegian University of Life SciencesChristina Steppeler17 4. Feeding experiment

Thank you for your attention! Norwegian University of Life SciencesProject Presentation – Christina Steppeler18

Norwegian University of Life SciencesChristina Steppeler19 Digestive fluids