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International audience; Methionine (Met) is an essential amino acid (AA) in pigs and the third limiting AA in cereal based diets. Met supplementation improves animal’s performance and protein gain. Besides, Met is considered as an important factor in the control of oxidative status with potential benefits on health and meat quality. This study aimed at investigating the effects of dietary Met provided in excess relative to growth requirements on muscle metabolism in finishing pigs. During the last 14 days before slaughter, crossbred pigs were individually fed diets (13.6% protein, 5.8% fat, 10.8 MJ/kg Net energy, 0.73% Lys) supplemented (Met++) or not (CONT) with OH-Met (n=15 pigs/diet). Dietary Met content was 0.22% and 1.1% in CONT and Met++ diets, respectively. Growth rate, carcass lean meat content and Longissimus muscle (LM) weight at slaughter did not differ between the two groups. In LM, the free AA profile was modified (P

Part of special issue: The 5th International Conference on Food Digestion - Edited by Didier Dupont, Pasquale Ferranti, Alan Mackie 5. International Conference on Food Digestion (INFOGEST) ; Rennes (France) - (2017-04-04 - 2017-04-06) / Conférence; In the frame of the COST action INFOGEST, a static in vitro digestion protocol has been elaborated aiming at the improvement of data comparability by harmonizing the experimental conditions. The success in harmonization was confirmed with inter-laboratory trials using skim milk powder as a standardized model food. Moreover, the physiological relevance of the gastric and intestinal endpoints of the static digestion protocol was demonstrated in a pig in vivo trial, with the same skim milk powder and samples collected from different sections of the digestive tract, as well as in a human study with from jejunal effluents. In vivo, digestion is a dynamic process influenced by peristalsis and by the gradual secretion of enzymes and juices and the dwell time of the food. To mimic these physiological mechanisms, dynamic in vitro digestion protocols are widely used. Until now, the differences of protein hydrolysis taking place during dynamic and static in vitro digestion have not been investigated.In this study, the gradual hydrolysis of the main milk proteins present in skim milk powder was digested with the dynamic DIDGI®-system using adult digestion protocol and the static harmonized INFOGEST method. Protein hydrolysis was analyzed by gel electrophoresis, peptide patterns were measured with mass spectrometry, and free amino acids with high pressure liquid chromatography. The peptide patterns at the gastric and intestinal endpoints of in vitro digestion showed a good approximation to the in vivo results from pigs. Moreover, gradual peptide generation was comparable in both in vitro digestion conditions. However, the dynamic protocol reflected the physiological situation better at the level of free amino acid release. Nonetheless, in both in vitro digestion protocols, absorption of free amino acids is not simulated, and they are therefore limited in reflecting the in vivo situation at this level.

Dietary extra hydroxyl-methionine supply: associated changes in muscle biological processes in finishing pigs

International audience; We analysed the effects of L-amino acid combinations, tested at the same relative concentrations as in 500 mgl1 of a filtrated Tubifex extract, on attraction and exploratory behaviour of juvenile carp, Cyprinus curpio L., in an olfactometer. Tubifex filtrate was significantly active in the range of concentrations tested (5 mgl−1, 50 mgl−1, 500 mgl−1, 5 gl−1). Maximum attraction was obtained in response to a concentration of 500 mg l−1. Soluble TCA fraction and a mixture of the 17 synthetic amino acids found in this fraction also showed significant effects on attraction and exploratory behaviour. Tests of the four chemical groups of amino acids gave the following results: acidic amino acids (aspartic and glutamic) did not produce significant activity. Basic amino acids (histidine, arginine and lysine) and polar, uncharged amino acids (glycine, serine, threonine, tyrosine, asparagine and glutamine) were ineffective as attractants but significantly increased exploration. Non-polar amino acids (alanine, valine, leucine, isoleucine, phenylalanine, and methionine) showed significant effects on both attraction and exploration. In tests where different pairs of these amino acid groups were mixed it was shown that a combination of non-polar amino acids and polar uncharged amino acids was the most effective in inducing both attraction and exploration. The simplest combination to have a significant effect on both attraction and exploration was alanine, valine and glycine. These results are discussed in the light of recent data on the role of free amino acids in the behaviour of fishes.

The growth and development under field conditions of the pods and seeds of two cvs of Trigonella foenum graecum are described. Samples were harvested at different stages of ripeness for the determination of dry matter, protein and free amino acid content. During maturation, reserves of solutes are established in the pod wall before the seeds begin their exponential phase of growth. Later, these reserves disappear, providing about 20% of the seed's requirements for nitrogen. SDS-electrophoresis was used to follow the formation of proteins and it was shown that the synthesis of storage proteins takes place prior to dehydration of the seed. Production soluble nitrogenous compounds precedes protein accumulation. Free amino acids follow the same pattern. 4-Hydroxyisoleucine represents nearly 80% of free amino acid of dry seeds. The concentration does not decrease in the later stages of maturation of the seed but this unusual amino acid is absent in the storage proteins of the seeds.

1. 1. Free amino acid contents in skin mucus extracts were analysed in sexually undinerentiated yellow eels, female yellow eels and male and female silver eels trapped at the same time from the same freshwater location. 2. 2. Total free amino acid contents in skin mucus were similar in the three groups of sexually differentiated eels (16.2–18.2μM/g dry weight). In sexually undinerentiated yellow eels, total content was higher (39.6μM/g dry weight). 3. 3. Free amino acid composition of skin mucus from male and female silver eels were similar. Compared with the two groups of yellow eels, main differences were found in taurine and non-essential amino acid relative contents. 4. 4. Taurine, glycine and alanine concentrations in skin mucus decreased as the level of sexual maturity of the eel increased. 5. 5. Possible influences of nutritional and hormonal factors on the free amino acid content of eel skin mucus are discussed. Potential consequences in osmoregulatory processes and intraspecific chemocommunication of the eel are also considered.

International audience; Proteolysis is a major event during cheese ripening. In Emmental cheese, the contribution of plasmin and thermophilic lactic starters to proteolysis has been well established. Our aim was to assess the contribution of each ripening flora to secondary proteolysis. With this aim, we used the aqueous phase (or juice) of Emmental cheese as a culture medium, which contains the enzymes released by thermophilic starters. Crude juice (containing all cheese flora) and cell-free juice either inoculated with two propionibacteria (PAB) strains or uninoculated (control), were incubated under anaerobiosis at 24 °C for 20 d. Free amino groups and free amino acids, bacterial growth and organic acids were followed throughout the incubation time. Facultatively heterofermentative lactobacilli (FHL) represented the main flora growing in crude juice up to 10 d incubation. FHL and PAB respectively reached 4.0 $\times$ 10$^8$ and 1.0 $\times$ 10$^{10}$ cfu$\cdot$mL$^{-1}$ of juice and consumed citrate and lactate, in accordance with that already observed in cheese. The level of amino groups increased linearly during incubation time by a factor of 1.9 in crude juice, 1.7 in cell-free juice and only 1.5 in juice inoculated with PAB strains, showing that the enzymes of thermophilic starters are the main contributors to secondary proteolysis. FHL growth resulted in a 16% increase in free amino acids compared to cell-free juice and in exhaustion of Arg and His. Both PAB strains caused a 18-27% decrease in free amino acids and also modified the amino acid distribution, with consumption of Asp, Gly, Glu, Ser and Ile.; Les lactobacilles hétérofermentaires facultatifs et les bactéries propioniques ont une faible contribution à la protéolyse secondaire de l'Emmental. La protéolyse est un phénomène majeur dans l'affinage du fromage. Dans l'Emmental, la contribution de la plasmine et des levains thermophiles à la protéolyse secondaire a été bien établie. Le but de cette étude était de déterminer la contribution de chacune des flores d'affinage à la protéolyse secondaire. Pour cela, nous avons utilisé de la phase aqueuse d'Emmental (ou jus), qui contient les enzymes relarguées par les levains thermophiles lors de leur lyse, comme milieu de culture. Le jus de fromage brut (contenant toutes les flores du fromage), le jus exempt de cellules bactériennes utilisé soit tel quel (témoin), soit ensemencé avec deux souches de bactéries propioniques (PAB) ont été incubés en anaérobiose à 24 °C pendant 20 j. Les groupements aminés libres et les acides aminés libres ainsi que les paramètres de croissance et de fermentation ont été suivis durant l'incubation. Les lactobacilles hétérofermentaires facultatifs (FHL) représentaient la flore principale poussant dans le jus brut jusqu'à dix jours d'incubation. Les FHL et les PAB atteignaient respectivement 4,0 $\times$ 10$^8$ and 1,0 $\times$ 10$^{10}$ ufc$\cdot$mL$^{-1}$ de jus et consommaient le lactate et le citrate, en accord avec les résultats déjà observés dans le fromage. Les taux de groupements amines libres augmentaient linéairement pendant l'incubation par un facteur 1,9 dans le jus brut, 1,7 dans le jus témoin et seulement 1,5 dans le jus ensemencé avec les souches de PAB, montrant que les enzymes des levains thermophiles contribuent majoritairement à la protéolyse secondaire. La croissance des FHL résultait en un accroissement de 16 % des acides aminés libres par rapport au jus témoin, et une disparition de Arg et His. Chacune des deux souches de PAB entraînait une chute de 18-27 % en acides aminés libres et modifiait également la distribution en acides aminés, en consommant Asp, Gly, Glu, Ser et Ile.