| Abstract | U ovome radu ispitan je utjecaj procesnih uvjeta (broj plagova - P, masa kukuruzne silaže - m, pH i vrijeme fermentacije) biološke obrade kukuruzne silaže na ekstrakciju fenolnih spojeva (ukupnih fenolnih spojeva, ukupnih flavonoida i fenolnih kiselina: p-kumarinske, ferulične i kafeinske) metodom odzivnih površina prema Box-Behnkenovom planu pokusa. Biološka obrada uzoraka provedena je u uvjetima fermentacije na čvrstim nosačima, pomodu gljive bijelog truljenja Trametes versicolor. Biološki obrađeni uzorci osušeni su pri 45 °C tijekom 48 h, te su nakon toga podvrgnuti ekstrakciji (uvjeti ekstrakcije: 50% otopina etanola/80 °C/120 min/200 rpm).
U ekstraktima biološki obrađene kukuruzne silaže spektrofotometrijskim metodama analizirani su ukupni fenolni spojevi (Folin-Ciocalteuovom metodm - 9,47 mgGAE/gs.t. i Prussian-Blue metodom – 0,55 mgGAE/gs.t.) i ukupni flavonoidi (1,47 mgCE/gs.t.) te su HPLC metodom određene individualne fenolne kiseline (p-kumarinska: 0,36 mg/gs.t, ferulična: 0,27 mg/gs.t i kafeinska: 0,14 mg/gs.t.). Broj plagova gljive T. versicolor i masa kukuruzne silaže tijekom procesa biološke obrade imali su najvedi utjecaj na prinos fenolnih tvari.
Za opisivanje procesa biološke obrade kukuruzne silaže korišten je kvadratni polinom koji je dobro opisivao ispitivani proces s ciljem dobivanja maksimalnog prinosa analiziranih fenolnih tvari. Ipak, najbolja slaganja modelom predviđenih podataka i eksperimentalnih rezultata uočena su kod kafeinske kiseline. Metodom odzivnih površina određeni su optimalni uvjeti biološke obrade kukuruzne silaže s ciljem dobivanja maksimalnog prinosa ispitivanih spojeva. Kod kafeinske kiseline optimalni uvjeti su: 9 plagova, 40 g kukuruzne silaže, pH 9 i 10 dana fermentacije. Pri tim uvjetima predviđeni maksimalni prinos kafeinske kiseline koji bi se mogao ekstrahirati je 0,14 mg/gs.t. što je u skladu s eksperimentalno određenim maksimalnim prinosom kafeinske kiseline. |
| Abstract (english) | The influence of process conditions (number of plugs - P, mass of corn silage – m, pH and duration of fermentation) in biological treatment of corn silage on extractability of phenolic compounds (total phenols, total flavonoids and phenolic acids: p-coumaric acid, fenolic acid and caffeic acid) was investigated using response surface methodology (Box-Behneken design).
Biological treatment was performedin condition of solid-state fermentation with white-rot fungi Trametes versicolor. Extraction of phenolic compounds from dried (at 45 °C/ 48h by oven) biollogically treted samples was performed using 50% aqueous ethanol solution, 80°C during 120 min.
Total phenolic compounds (FC method – 9.47 mgGAE/gdb and PB method – 0.55 mgGAE/gdb) and total flavonoids (1.47 mgCE/gdb) from biological treated samples were determined by spectrophotometric methods, while individual phenolic acids (p-coumaric: 0.36 mg/gdb, ferulicacid: 0.27 mg/gdb i caffeic acid: 0.14 mg/gdb) were analyzed by HPLC device. Number of Trametes versicolor plugs and mass of corn silage had the highest impact on extraction yield of phenolic compounds.
Quadratic polinom was used to describe biological treatment of corn silage in order to maximize phenolic compounds yield. However, the best matching of predicted data and experimental results was noticed with caffeic acid.
Response surface methodology was used for determination of optimal conditions for biological treatment of corn silage in order to maximize the analyzed compounds yield. Optimal conditions for maximum caffeic acid yield were: 9 plugs, 40g of corn silage, pH 9 and 10 days of fermentation. However, in these conditions maximum caffeic acid yield that could be extracted is 0.14 mg/gdb, which is in accordance with maximum experimental caffeic acid yield. |
