| Abstract | U radu je ispitivan utjecaj temperature ekstrakcije (30, 60 i 90 °C), sastava otapala (30, 60 i 90% etanol, v/v) i vremena ekstrakcije (10, 40 i 70 min.) te njihova interakcija na ekstraktibilnost ukupnih fenolnih tvari i flavonoida iz brašna cjelovitog zrna pšenice. Istraživanja su provedena na slijedećim uzorcima pšenice: Kutjevo d.d.(PK), Čakovečki mlinovi (PČM) i Belje (PB). Metodom odzivnih površina određeni su optimalni uvjeti ekstrakcije u vodenoj kupelji za fenolne tvari: otapalo 58%-tni etanol, temperatura 83 °C i vrijeme 70 minuta. Pri navedenim optimalnim uvjetima modelom predviđen maksimalni prinos ukupnih fenolnih tvari iznosio je: za PK 3,7 mgGAE/gs.t., za PČM 3,26 mgGAE/gs.t. te za PB 3,35 mgGAE/gs.t.. Određeni optimalni uvjeti ekstrakcije za flavonoide su: otapalo 90%-tni etanol; temperatura 44 °C i vrijeme 70 minuta, pri kojima je modelom predviđen maksimalni prinos ukupnih flavonoida iznosio: za PK 2,42 mgCE/gs.t., PČM 2,2 mgCE/gs.t. te PB 2,63 mgCE/gs.t.. Ekstrakcijom fenolnih spojeva u vodenoj kupelji (pri optimalnim uvjetima radi provjere uspješnosti optimiranja) dobiveni su maseni udjeli ukupnih fenolnih tvari: PK 3,67 mgGAE/gs.t., PČM 3,33 mgGAE/gs.t. i PB 3,33 mgGAE/gs.t, a udio flavonoida je iznosio: PK 2,36 mgCE/gs.t., 2,55 mgCE/gs.t., PČM i 2,65 mgCE/gs.t. PB. Ekstrakcija na univerzalnom sustavu za ekstrakciju (Büchi-LSV) je provedena standardnom Soxhlet metodom (s ciljem prevođenja ekstrakcije u veće mjerilo) pri čemu je udio ukupnih fenola bio: PK 2,42 mgGAE/gs.t., PČM 2,24 mgGAE/gs.t. i PB 2,32 mgGAE/gs.t., a udio flavonoida: PK 2,82 mgCE/gs.t., 2,54 mgCE/gs.t., PČM i 2,53 mgCE/gs.t. za PB. Eksperimentalni rezultati dobiveni pri navedenim optimalnim uvjetima ekstrakcije pokazali su dobra slaganja s podacima predviđenim kvadratnim modelom. |
| Abstract (english) | The effects of extraction temperature (30, 60 i 90°C), ethanol/water solution (30, 60 i 90%, v/v) and the duration of the extraction (10, 40 i 70 min) as well as their interaction on total phenolic and flavonoid compounds extractability from wholegrain wheat flour were studied. Studied samples were collected from different locations in Croatia (Kutjevo (PK), Čakovečki mlinovi (PČM) and Belje, Beli Manastir (PB)).
The optimal conditions for extraction of the total phenolic compounds were determined by response surface methodology based on Box-Bhenken experimental design as follows: solvent 58% v/v ethanol/water, temperature 83 °C and time 70 min. The maximum yield of total phenolic compounds predicted by the quadratic model was for PK 3.7 mgGAE/gdb, PČM 3.26 mgGAE/gdb and PB 3.35 mgGAE/gdb. Determined optimal conditions for extraction of the flavonoids compounds were: solvent 90% v/v ethanol/water; temperature 44 °C and time 70 minutes and the model predicted maximum yield of total flavonoid compounds were: PK 2.42 mgCE/gdb, PČM 2.2 mgCE/gdb and PB 2.63 mgCE/gdb. Optimization efficieny of the extraction process is estimated by implementation of extraction in certain optimal conditions in a water bath and on the universal extraction system Büchi-LSV with an aim to convert extraction in a bigger scale. Results obtained in a water bath for total phenolic compounds were: PK 3.67 mgGAE/gdb, PČM 3.33 mgGAE/gdb and PB 3.33 mgGAE/gdb and for flavonoid compounds were: PK 2.36 mgCE/gdb, 2.55 mgCE/gdb, PČM i 2.65 mgCE/gdb PB. Extraction at the universal extraction system (Büchi-LSV) is carried out by standard Soxhlet metodology and content of total phenolic compounds were: PK 2.42 mgGAE/gdb, PČM 2.24 mgGAE/gdb, PB 2.32 mgGAE/gdb and for flavonoids: 2.82 mgCE/gdb PK, 2.54 mgCE/gdb PČM, 2.53 mgCE/gdb PB. Results indicate that experimental results obtained under the above optimum extraction conditions showed good agreement with the data provided by quadratic model. |
