Trimetilamin Oksida ( Kajian pada ikan segar dan ikan beku )

1. TrimetilaminOksida(Kajianpadaikansegardanikanbeku) YunitaEkaPuspitasari, S.Pi, MP FakultasPerikanandanIlmuKelautan UniversitasBrawijaya yunita_ep@ub.ac.id

2. selaluberkaitandenganpembusukanikansegarmaupunikanbeku. • Banyakditemukan di ikanlaut, khususnya di famili gadoid (Gadidae) danelasmobranchi (hiu) (2,5% dw) • Adanya TMAO terkaitdengansistemosmoregulasi • Tidakditemukan di ikandarat (freshwater fish) dalamjumlahbanyak, akantetapibeberapaikanlaut yang bermigrasikeperairandarat, kandungan TMAO-nyahampirtidakada SAAT berada di perairandarat. • TMAO larut air danbagiandarifraksi NPN

3. Kadar TMAO di ikanbervariasi tergantungpada : - musim - ukuran - umurikan - kondisilingkungan

4. 1 mg TMAO-N = 5,38 mg TMAO = 72µmoles 1 mg TMA-N = 4,22 mg TMA = 72µmoles 1 mg DMA-N = 3,22 mg DMA = 72µmoles 2,16 mg FA = 72µmoles

5. Tabel 2. Kandungan TMAO padaberbagaispesiesikan Tabel 3. Kandungan TMAO pada organ yang berbeda

6. Perubahanbiokimiaikanpasca mortem diikutijugadenganperubahanmikrobiologi. • Aktifitasmikrobiologidari • Mikroorganismedalamtubuhikansendiri • Kontaminasiselama handling • Bakteri yang berperandalam proses pembusukan al: • Bakteri gram negatif – psikotrofik • Achromobacter • Pseudomonas putrefaciens • Reaksibakteri : AH2 + (CH3)3NO  A + (CH3)3N + H2O

7. Tabel 4. Odor Thresholds • TMA  volatile compound + very low odor threshold • TMA  fishy odor of spoilage • Bacterial flora • Cellular processes Other odoriferous compounds

8. SUBSTRAT • Perananenzimbakteridalamproduksi TMA • Enzimmenggunakansenyawaseperti • TMA, • (CH3CH2)3NO, • TripropilamineOksida ( CH3CH2CH2)3NO • Mengaktivasisubstrat dehidrogenasedalamselbakteri • SejumlahsenyawaberperansebagaisumberHidrogen CH3CHOHCO2H + TMAO  CH3COCO2H + TMA + H20 AsamlaktatAsampiruvat CH3COCO2H + TMAO + H2O  CH3CO2H + CO2+TMA+H20 Asamasetat

9. The origin and synthetic pathways of TMAO are actively debated • TMAO stimulates the anaerobic growth of bacteria in fish muscle extracts • TMAO, like most methylamines, is derived from the trimethylammonium group of choline. Dietary choline may be oxidized to trimethylamine by bacteria in the gut of marine animals. • The accumulation of TMA in rotting fish as a result of bacterial degradation of choline, as well as the reduction of TMAO to TMA, is responsible for their characteristic ‘fishy’ odor (Hebard et al., 1982; Sotelo and Rehbein, 2000).

10. Menjagakesegarandankualitasikan ??? • Antibiotik ? • Antimikroba ? • Antimikotik ? • Bahankimia ? • Temperatur ? • Mengontrolbakteri  modified atmosphere ? TMA diproduksi  suhu 0 – (-6)°C

11. Hebarda, C.E. G.J. Fillick and R.E. Martin. Occurance and Significance of TMAO and Its Derivataves in Fish and Shellfish. AVI Publishing Company • Regenstin, J.M., M. A. Schlosser, A. Samson and M. Fey. Chemical changes of TMAO During Fresh and Frozen Storage Fish. AVI Publishing Company • STR~MA,. R. 1971. Bakterielleomsetninger I anaerobtsilde-ekstrakt. Lic. techn. thesis, Norwegian Institute of Technology, University of Trondheim, Norway • Seibel, B.A and Patrick J. Walsh. 2002. Trimethylamine oxide accumulation in marine animals: relationship to acylglycerol storage. The Journal of Experimental Biology 205, 297–306

12. Next week • Mekanismepembentukan TMAO • Oksidasienzim (?) • Oksidasimikroba (?) • Reduksi TMAO menjadi TMA dan DMA dan FA • Perananbakteri ? (bakteripembusuk, bakteripenghasil TMA, pengaruhlingkungan) • Secaraenzimatik / non enzimatik • Histaminpadaikan