Brestaz, P.

Genot, C.

Jacobsen, Charlotte

Meynier, A.

Ribourg, L.

Thomsen, Birgitte Raagaard

Viau, M.

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Dec 20, 2017Lipid oxidation during instrumented dynamic in vitro digestion of marine oil-enrichedmilkMeynier, A.; Jacobsen, Charlotte; Thomsen, Birgitte Raagaard; Brestaz, P.; Ribourg, L.; Viau, M.; Genot,C.Publication date:2014Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Meynier, A., Jacobsen, C., Thomsen, B. R., Brestaz, P., Ribourg, L., Viau, M., & Genot, C. (2014). Lipidoxidation during instrumented dynamic in vitro digestion of marine oil-enriched milk. Poster session presented at12th Euro Fed Lipid Congress, Montpellier, France.The health benefits of n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are well recognized. Foods enriched in n-3 LC-PUFA, are now available for the consumers. However, PUFA are prone to oxidation during processing and storage of the enriched-foods, but also during their digestion, and deleterious compounds can be formed both during both gastric and intestinal steps [1].  A. Meynier, C. Jacobsen, B.R. Thomsen, P. Brestaz, L. Ribourg, M. Viau, C. Genot,  Lipid oxidation during instrumented dynamic in vitro digestion of marine oil-enriched milk  Stomach pH regulated at 6.5 Marine-oil enriched milk 1% milk fat,  0.5% fish oil Intestine Fish oil 0.5 % (w/w) PV = 2.4 meq/kg ; AV = 7.55 MDA: 68 nmole/g oil 4-HHE: 0.8 nmole/g oil oil 4-HNE: 0.18 nmole/g oil Tocopherols : 890 µg/g oil EPA + DHA : 11 % total fatty acids n-6/n-3 PUFAs : 0.26 Homogenized pasteurized milk  1% fat  Homogenization (300 bars, 2.5 min) The aim of this study was to evaluate the formation of toxic aldehydes: malondialdehyde (MDA),  4-hydroxy-2-hexenal (4-HHE),    4-hydroxy-2-nonenal (4-HNE) during the in vitro digestion of marine oil enriched milk. Milk enrichment Material & Methods  CJ, AM, and CG participate to Infogest COST action FA1005  Results & Discussion Lipid oxidation in the stomach compartment Lipid oxidation in the intestine compartment Conclusions Toxic aldehydes (MDA >> 4-HHE >> 4-HNE) were formed during the gastric and intestinal steps of the in vitro digestion of the marine oil-enriched milk. Tocopherols were consumed mostly during the gastric step. Results must be confirmed by in vivo studies, to evaluate in the case of n-3 LC-PUFA enriched-foods, the health effects of the oxidative reactions during digestion.  References Ingestion rate (100mL/3 min) 01020304050600 50 100 150 200vol (mL)Time (min)sampling timeend of gastric emptyingstart intestinal emptyiing01000200030004000500060000 25 50 75 100G1G2G3GmeanMDA nmolesTime (min)02004006008001000120014000 25 50 75 100 125 150 175 200 225I1I2I3I meanMDA nmolesTime (min)01002003004005000 20 40 60 80 100 120G1G2G3Gmean4-HHE nmolesTime (min)010203040500 20 40 60 80 100 120G1G2G3Gmean4-HNE nmolesTime (min)0204060801001201400 50 100 150 200 250I1I2I3I mean4-HHE nmolesTime (min)0510150 50 100 150 200 250I1I2I3I mean4-HNE nmolesTime (min)040801200 50 100 150 200 250Time (min)Tocopherols (µg/g lipids)040801201602000 20 40 60 80 100 120Time (min)Tocopherols (µg/g lipids)MDA can result from the oxidation of both n-6 and n-3 PUFAs. It is toxic for cells (2,3). It was produced in fairly high concentrations (75 µM at the end of the gastric phase) which corresponds to around 4 µmoles in the total digestive fluid  and 1.2 µmoles/g ingested lipids During the gastric step, toxic aldehydes such as MDA and 4-HHE were formed while tocopherols were consumed. The results confirm that oxidation of the n-3 PUFAs of marine oil-enriched milk took place in conditions close to real gastric conditions (pH variation, 5), even in the absence of oxidation initiator such as heme iron. Three digestions were performed independently on three marine oil-enriched milks prepared separately.  MDA, 4-HHE and 4-HNE were measured on the samples from the 3 experiments. The individual data obtained for MDA (left), 4-HHE (middle) and 4-HNE  (right)  during the  gastric (blue  symbols, G1, G2, G3) and intestinal steps (red symbols,  I1, I2, I3) of each digestion are shown. The blue and red lines locate the mean values.  Total amounts in each compartment (nmoles) calculated from volumes of digestive media are presented.    4-HHE results from oxidation of n-3 PUFAs. It is very reactive and binds to proteins. It can be absorbed by the intestinal cells and provokes oxidative stress (4). It was produced continuously in the acid gastric environment. It represented up to 7 µM digestive medium, meaning total of 400 nmoles and around 800 nmoles/g lipids. 4-HNE originates from the oxidation of n-6 PUFAs. This reactive compound is considered as a marker of oxidative stress in vivo (2). In accordance with the fatty acid composition of the fish oil, poor in n-6 PUFAs, its  amounts remained fairly low as compared to MDA and 4-HHE: around 0.3 µM, 20 nmoles and 50 nmoles/g lipids. MDA and 4-HHE concentrations increased  continuously in the intestinal conditions. However, their concentrations were lower than in the  gastric medium. It could result from the dilution by the digestive fluids and from the binding of the reactive aldehydes to the components of the medium, including the hydrolyzed milk proteins. The decrease of MDA and 4-HHE total amounts at the end of the intestinal step is linked to the decrease of the fluid volume (emptying). 4-HNE was not appreciably produced during intestinal digestion of  marine oil-enriched milk.   Tocopherol  concentrations  remained fairly stable  during most of the intestinal step. The decrease observed after 165 min is tentatively attributed to the high dilution of the lipids contained in the meal in those  belonging to the digestive fluids . Oxidation and production of MDA and 4-HHE continued during the intestinal simulated digestion.   1- Kenmogne-Domguia H.B., et al. 2014. Food Chem. 152, 146-154, 2- Esterbauer et al. 1991. Free Rad. Biol. Med. 11, 81-128 ; 3- Niedernhofer L.J. et al. 2003. J  Biol. Chem. 278, 31426-31433, 4– Awada M. et al. 2013. J. Lipid Res.  53, 2069-2080, 5-Tyssandier V. et al. 2003. Am. J. Physiol. Gastrointest Liver Physiol. 284, G913-G923.  012345670 50 100 150 200pHTime (min)end of emptyingsampling pointFinancial support of NFOGEST for short term mission of CJ is acknowledged 

Lipid oxidation during instrumented dynamic in vitro digestion of marine oil-enriched milk

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Lipid oxidation during instrumented dynamic in vitro digestion of marine oil-enriched milk

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