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Prace poukazuje na možnost využiti FT NIR spektrometru pro zjisťovani zralosti eidamských sýrů a pro rychlou optimalizaci suroviny na výrobu tavených sýrů na zakladě zjisťovani obsahu rozpustneho dusiku, tyrozin a tryptofanu v eidamských sýrech. K analýze množstvi rozpustneho dusiku, tyrozinu a tryptofanu byly použity vzorky eidamských bloků o 45 % TVS. Stanoveni jednotlivých ukazatelů se provadělo spektrofotometricky extinkci při vlnove delce 270 nm a 290 nm. Z naměřených hodnot byly na zakladě empirických vzorců vypocteny obsahy rozpustneho dusiku, tyrozinu a tryptofanu. Nasledně byly vzorky měřeny dvěma způsoby na FT NIR spektrometru. Pomoci sondy (S), kde byl použit platek sýra a na integracni sfeře (IS) v kyvetě, kde byl použit rozstrouhaný sýr. Korelacni koeficienty (R) kalibrace stanovene na integracni sfeře byly pro rozpustný dusik 0,922, pro tyrozin 0,911 a pro tryptofan 0,852. Pomoci opticke sondy byly stanoveny korelacni koeficienty (R) kalibrace pro rozpustný dusik 0,996, pro tyrozin 0,958 a pro tryptofan 0,922. Na zakladě výsledků t-testu nebyl zjistěn statisticky průkazný rozdil mezi referencni a instrumentalni (NIR) metodou.Z výsledků vyplýva, že FT NIR spektroskopie může sloužit pro orientacni stanoveni zralosti eidamských sýrů. Tato metoda je tedy vhodna pro rutinni technologickou kontrolu, kdy je rychlost casto důležitějsi než vysoka přesnost a umožňuje optimalni připravu suroviny pro výrobu tavených sýrů s požadovanými reologickými vlastnostmi.

In this thesis report, we describe a novel home-built instrument designed to study the spectroscopy of biomolecular ions in the gas phase and at low temperature, and we present the first experimental results obtained on protonated aromatic amino acids. The apparatus consists in a tandem mass spectrometer equipped with a nanospray ion source and a cryocooled 22-pole ion trap. The charged species produced by the source traverse a first quadrupole mass filter and mass-selected ions are then accumulated and thermalized in the ion trap, where their vibrational temperature can be lowered to ~ 10 K. Two setups allow us to generate ultraviolet and infrared laser light to spectroscopically probe the trapped ions by photodissociation. The resulting fragment ions are finally released from the trap and mass analyzed by a second quadrupole spectrometer. Photodissociation electronic spectra have been measured for the protonated amino acids tryptophan (TrpH+) and tyrosine (TyrH+), as well as for hydrated complexes of the former. The spectrum of TyrH+ exhibits sharp, fully resolved vibronic transitions, which attests to the low temperature of the ions. In contrast, that of tryptophan shows a broad absorption band that covers several hundreds of wavenumbers. This has been attributed to lifetime broadening related to an ultrafast (< ~ 100 fs) deactivation mechanism of the TrpH+ S1(ππ*) excited state. This phenomenon is caused by a strong coupling between this ππ* state and a nearby dissociative state of πσ* character mainly localized on the charged ammonium group. Solvation of TrpH+ by only two water molecules is sufficient to significantly destabilize the σ* orbitals and reduce that coupling, which results in a longer excited-state lifetime and a fully resolved electronic spectrum. These interpretations are supported by ab initio and density functional theory (DFT) calculations. Infrared-ultraviolet double resonance spectroscopic techniques have been successfully implemented to identify the different conformers of TyrH+ and doubly hydrated protonated tryptophan (TrpH+·W2) by measuring conformer-specific vibrational and electronic spectra for each of them. By comparison with the results of DFT geometry and harmonic frequency calculations, we could confidently determine the structures of the TyrH+ conformers and suggest possible assignments for those of TrpH+·W2. Two important stabilizing interactions could be inferred from these results: (i) the attraction between the charged ammonium group and the π-electron cloud of the aromatic ring; (ii) the hydrogen-bonding interaction of a donor water molecule to the acceptor indole ring of TrpH+·W2.

Cet article traite des données récentes sur les relations d’équilibre entre les acides aminés dans l’alimentation du porc en croissance, au travers du concept de la protéine "idéale". Après avoir précisé les limites de ce concept, sur le plan de la constance des rapports entre les teneurs en acides aminés indispensables et celle en lysine, prise comme référence, sont considérés les ratios entre les acides aminés limitants secondaires (tryptophane, thréonine, méthionine et acides aminés soufrés) et la lysine, compte tenu des spécificités de leur rôle fonctionnel au plan métabolique et physiologique. Pour cela, l’incidence des écarts entre le profil de composition en acides aminés de la protéine alimentaire et celui de la protéine idéale (excès de protéines) sur l’ingestion alimentaire et les performances de croissance est étudiée selon la nature de l’acide aminé le plus limitant. En raison de sa faible contribution aux processus métaboliques autres que ceux concernant la synthèse de protéines corporelles, la lysine constitue une référence stable pour l’expression des rapports entre les acides aminés. A la différence de la lysine, le tryptophane interagit fortement et négativement avec les protéines excédentaires (acides aminés neutres de grande taille) au niveau de l’appétit et de la croissance, en liaison avec un dysfonctionnement du système sérotoninergique. Ceci met en défaut la constance du rapport tryptophane / lysine, qui devrait être corrigé sur la base d’un ratio minimum tryptophane / acides aminés neutres de 4 %, pour se prémunir d’un risque d’excès de ces derniers dans certaines protéines alimentaires. Dans le cas de la thréonine, lorsqu’elle est limitante, il ressort une interaction positive avec les acides aminés non indispensables (acide glutamique). L’équilibre méthionine / cystine a été reconsidéré en fonction des données récentes de la bibliographie. En conclusion, les recommandations concernant les rapports acides aminés / lysine pour le porc en croissance ont été réactualisées., The present review was intended to provide recent information on the relationships between dietary amino acids in growing pigs, through the concept of “ideal” protein. The limits of this concept were given, namely with regards to the constant ratios between essential amino acids and lysine, as a reference. The ratios between secondary limiting amino acids (tryptophan, threonine, methionine and sulphur amino acids) and lysine were considered, according to their specific functional role in metabolic and physiological processes. For this purpose, the effects of the deviations between amino acid profiles of dietary and ideal protein (excess protein) on voluntary feed intake and growth performance were investigated, in relation to the most limiting amino acid. Owing to its poor contribution to metabolic processes, lysine is a stable reference for expressing ratios between essential amino acids. Unlike lysine, dietary tryptophan interacts heavily and negatively with excess protein (large neutral amino acids), through brain serotonin dysfunction, in relation to depressed appetite and growth. In practice, the tryptophan / lysine ratio should not be considered as a constant. It should be corrected on the basis of a minimum ratio between tryptophan and large neutral amino acids of 4 %, in order to prevent an eventual risk of their excess in some dietary protein. In the case of threonine, when it is limiting, a positive interaction with non essential amino acids (glutamic acid) was reported. Dietary balance between methionine and cystine was re-evaluated in accordance with the recent data from literature. To conclude, the revised essential amino acid to lysine ratios for the growing pig were given.