High True Ileal Digestibility but Not Postprandial Utilization of Nitrogen from Bovine Meat Protein in Humans Is Moderately Decreased by High-Temperature, Long-Duration Cooking.
BACKGROUND
Meat protein digestibility can be impaired because of indigestible protein aggregates that form during cooking. When the aggregates are subsequently fermented by the microbiota, they can generate potentially harmful compounds for the colonic mucosa.


OBJECTIVE
This study evaluated the quantity of bovine meat protein escaping digestion in the human small intestine and the metabolic fate of exogenous nitrogen, depending on cooking processes.


METHODS
Sixteen volunteers (5 women and 11 men; aged 28 ± 8 y) were equipped with a double lumen intestinal tube positioned at the ileal level. They received a test meal exclusively composed of 120 g of intrinsically (15)N-labeled bovine meat, cooked either at 55°C for 5 min (n = 8) or at 90°C for 30 min (n = 8). Ileal effluents and blood and urine samples were collected over an 8-h period after the meal ingestion, and (15)N enrichments were measured to assess the digestibility of meat proteins and the transfer of dietary nitrogen into the metabolic pools.


RESULTS
Proteins tended to be less digestible for the meat cooked at 90°C for 30 min than at 55°C for 5 min (90.1% ± 2.1% vs. 94.1% ± 0.7% of ingested N; P = 0.08). However, the particle number and size in ileal digesta did not differ between groups. The appearance of variable amounts of intact fibers was observed by microscopy. The kinetics of (15)N appearance in plasma proteins, amino acids, and urea were similar between groups. The amount of exogenous nitrogen lost through deamination did not differ between groups (21.2% ± 0.8% of ingested N).


CONCLUSIONS
Cooking bovine meat at a high temperature for a long time can moderately decrease protein digestibility compared with cooking at a lower temperature for a short time and does not affect postprandial exogenous protein metabolism in young adults. The study was registered at www.clinicaltrials.gov as NCT01685307.
French National Institute for Agricultural Research (INRA) and AgroParisTech, Research Center for Human Nutrition Ilde de France, UMR914, Nutrition Physiology and Ingestive Behavior, Paris, France;
Marion
M
Oberli
French National Institute for Agricultural Research (INRA) and AgroParisTech, Research Center for Human Nutrition Ilde de France, UMR914, Nutrition Physiology and Ingestive Behavior, Paris, France;
Agnès
A
Marsset-Baglieri
French National Institute for Agricultural Research (INRA) and AgroParisTech, Research Center for Human Nutrition Ilde de France, UMR914, Nutrition Physiology and Ingestive Behavior, Paris, France;
Gheorghe
G
Airinei
French National Institute for Agricultural Research (INRA), UR370 Quality of Animal Products, Saint Genès Champanelle, France;
Véronique
V
Santé-Lhoutellier
French National Institute for Agricultural Research (INRA) and AgroParisTech, Research Center for Human Nutrition Ilde de France, UMR914, Nutrition Physiology and Ingestive Behavior, Paris, France;
Nadezda
N
Khodorova
French National Institute for Agricultural Research (INRA), Unit of Human Nutrition, Research Center for Human Nutrition Auvergne, Clermont-Ferrand, France; and Human Nutrition Unit, Clermont University, University d'Auvergne, Clermont-Ferrand, France.
Didier
D
Rémond
French National Institute for Agricultural Research (INRA) and AgroParisTech, Research Center for Human Nutrition Ilde de France, UMR914, Nutrition Physiology and Ingestive Behavior, Paris, France;
Angélique
A
Foucault-Simonin
French National Institute for Agricultural Research (INRA) and AgroParisTech, Research Center for Human Nutrition Ilde de France, UMR914, Nutrition Physiology and Ingestive Behavior, Paris, France;
Julien
J
Piedcoq
French National Institute for Agricultural Research (INRA) and AgroParisTech, Research Center for Human Nutrition Ilde de France, UMR914, Nutrition Physiology and Ingestive Behavior, Paris, France;
Daniel
D
Tomé
French National Institute for Agricultural Research (INRA) and AgroParisTech, Research Center for Human Nutrition Ilde de France, UMR914, Nutrition Physiology and Ingestive Behavior, Paris, France;
Gilles
G
Fromentin
French National Institute for Agricultural Research (INRA) and AgroParisTech, Research Center for Human Nutrition Ilde de France, UMR914, Nutrition Physiology and Ingestive Behavior, Paris, France;
Robert
R
Benamouzig
French National Institute for Agricultural Research (INRA) and AgroParisTech, Research Center for Human Nutrition Ilde de France, UMR914, Nutrition Physiology and Ingestive Behavior, Paris, France; claire.gaudichon@agroparistech.fr.
Claire
C
Gaudichon
D000328:Adult; D000818:Animals; D002417:Cattle; D003296:Cooking; D018592:Cross-Over Studies; D004044:Dietary Proteins / Q000378:metabolism*; D004063:Digestion; D005260:Female; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D007082:Ileum / Q000378:metabolism*; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D008460:Meat; D009584:Nitrogen / Q000097:blood / Q000378:metabolism / Q000652:urine; D009587:Nitrogen Isotopes; D016037:Single-Blind Method; D013997:Time Factors; D055815:Young Adult
D004044:Dietary Proteins; D009587:Nitrogen Isotopes; D009584:Nitrogen
digestion; healthy volunteers; postprandial; protein metabolism; stables isotopes