Schinken- und Rohwurstproduktion Production of Ham & Raw Sausage nes. In some stems of micro- Fleischproteine / meat proteins organisms the formation of bio- genic amines is a preferred way (Fleisch)peptidasen / meat peptidases as the organisms gain further energy in this process. In this Peptide / peptides Aminosäuren/ amino acids way the amines basically en- sure their survival at low pH- Transport/ transport Transport / transport extrazellulär values. The respective bioche- extracellular mical mechanisms depend on the stem. Therefore it is possi- Peptidasen intrazellulär ble to use adequate markers in peptidases intracellular order to identify certain speciesDecarboxylasen Aminosäuren decarboxylases or stems which don't form bio- amino acids Amine genic amins but are neverthe- – Ketoglutarat CO2 less competitive in a raw saus- age environment. Transaminasen Glutamatdehydrogenase transaminases glutamatde hydrogenase Volatile organic Glutamat/ glutamate compounds – Ketosäuren Dehydrogenasekomplex After transamination various racteristics of the organisms re- – keto acids dehydrogenase complex metabolic products may occur garding transport, peptidolysis CO2 and their key reactions of trans-(figure 1). Which compounds Phosphotransacetylase occur and what proportion they amination. CO2 Decarboxylasen Acylkinase have depends on the stem andphosphotransacetylase decarboxylases acyl kinase the environment. The actual Identification of stems Aldehyde/aldehydes Carboxylsäuren amino acid conversion not only At first 51 stems of L. sakei Aldehyddehydrogenasen carboxylic acids depends on the presence or and 28 stems of L. curvatus aldehyde dehydrogenases absence of an enzyme, it is also were examined in order to alcohol dehydrogenases related to the availability of establish their ability to formAlkoholdehydrogenasen essential co-subtrates such as amines. To this end biochemi- -ketogularate and NAD(P)H. cal tests on the formation of Alkohole/alcohols Of particular importance in the amines were conducted and formation of aroma-active, vo- PCR primer sets for the verifi- Abb. 1: Übersicht über Stoffwechselwege von Peptiden und Aminosäuren/ latile substances is the metabo- cation of the genes of the res- Image 1: Overview over metabolism ways of peptides and amino acids lism of the branched-chain ami- pective enzyme (hdc, tdc) were no acids Leucine, Valine and developed and used in a scree- Isoleucine, the aromatic amino ning of these stems. Weg sein, da die Organismen der Verfügbarkeit wichtiger Ko- acids, particularly Phenylala- This combined approach hierbei zusätzliche Energie ge- substrate, wie -Ketoglutarat nine, and the sulfic amino consisting of physiology and winnen können. Die Amine er- und NAD(P)H. Von besonderer acids Methionine and Cysteine. genetic screening was exten- möglichen damit im Endeffekt Bedeutung für die Bildung However, only the correlation ded in order to identify key das Überleben bei niedrigem aromaaktiver, flüchtiger Sub- of different aromatic sub- genes of the amino acid meta- pH-Wert. Die jeweiligen bio- stanzen ist der Stoffwechsel der stances, which exceed a certain bolism. As a result lead genes chemischen Mechanismen sind verzweigtkettigen Aminosäu- threshold value are perceived could be identified, which al- stammabhängig. Deswegen ist ren Leucin, Valin und Isoleucin, as raw sausage aroma. The low to distinguish toxic (poten- es möglich, anhand geeigneter der aromatischen Aminosäuren, identification of marker enzym- tially amine producing) stems Marker Spezies oder Stämme insbesondere Phenylalanin, und es and genes therefore at first from those with a high potential zu identifizieren, die keine bio- der schwefelhaltigen Amino- concentrates on the basic cha- of aroma formation. Therefore it (Abb. 1). Welche Verbindungen peptides and effective Foto: Richter, LMS/ Grafik: Vogel TU München/FEIthat don't have a po-tential to form histami-ne and tyramine butrather have a strongmetabolism of argini-ne and glutamaticacid. The transport ofis necessary to choose stemsNach der Transaminierunggenen Amine bilden und den-noch im Milieu Rohwurst wett-bewerbsstark sind.Flüchtige Verbindungen können unterschiedliche Stoff- wechselprodukte entstehen entstehen und in welchen Ver- trans-amination are hältnissen, ist sowohl stamm- important key factors als auch milieubedingt. Der for the formation of tatsächliche Aminosäurenum- Oben: Physiologischer Test auf Tyraminbil- volatile compounds satz wird nicht nur von der An- dung (dunkle Proben sind positiv)/ above: that contribute to the oder Abwesenheit des Enzyms physiological test for tyramine formation aroma of fermented bestimmt, sondern auch von (dark samples are positive) meat products. 28 4/2012
FT_04_2012
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