EXTRACTION OF PHENOLIC COMPOUNDS FROM MULBERRY FRUIT

Namen magistrske naloge je bil izvesti ekstrakcijo sadežev različnih sort murve in določiti kako procesni parametri vplivajo na antioksidativno aktivnost ekstraktov in vsebnost fenolnih spojin, antocianinov ter proantocianidinov. V raziskavah smo uporabili dve sorti murve, in sicer belo murvo (Morus alba) in črno murvo (Morus nigra). Za izvedbo ekstrakcije smo uporabili konvencionalni postopek in eksperimente načrtovali po Box-Behnkenovem eksperimentalnemu načrtu, ki je metodologija odzivne površine (Response Surface Methodology, RSM). V našem eksperimentalnem načrtu, ki smo ga načrtovali v programu Designe-Expert 7.0 smo spreminjali tri procesne parametre, in sicer razmerje aceton:voda (topilo), razmerje material:topilo in temperaturo. Vsaka izmed ekstrakcij je potekala 2 uri. Vsebnost celokupnih fenolov, proantocianidinov in celokupnih monomernih antocianinov smo v ekstraktih določevali s spektrofotometričnimi metodami. Glede na zahteve posameznih metod smo raztopinam ekstraktov izmerili absorbanco pri določeni valovni dolžini in nato iz umeritvene krivulje na podlagi izmerjene absorbance določili koncentracijo, ki smo jo podali kot maso na gram ekstrakta oz maso na gram materiala. Antioksidativno aktivnost ekstraktov smo podali kot % inhibicije in smo jo določili z DPPH prostoradikalsko metodo, kjer smo merili absorbanco raztopine vzorca in referenčne raztopine. Rezultati analiz so pokazali, da ima črna murva višjo vsebnost antioksidativnih komponent kot bela murva.The purpose of the master thesis was to implement extraction of different mulberry fruit species and to study the influence of different process parameters on antioxidant capacity of extracts, total phenolic, anthocyanin and proanthocyanidin content. Two species of mulberry fruit were used in the research, white mulberry (Morus alba) and black mulberry (Morus nigra). Conventional extraction process was used for the fruit extraction and Box-Behnken experimental design, which is response surface methodology, was used for the design of extraction experiments. Three different process parameters were warried in our experimental design, namely solvent composition (acetone/water ratio), material/solvent ratio and temperature, respectively. Each of the extraction experiments was carried out for two hours. Total phenolic, anthocyanin and proanthocyanidin content in the extracts were determined by spectrophotometric methods. Depending on the method, absorbance of the extract solution at certain wavelength was measured and concentration of the components was determined from calibration curve, which was expressed as mass per gram of extract or mass per gram of material. Antioxidant capacity of the extracts was expressed as % of inhibition of DPPH radical and was determined by DPPH free radical method, where absorbance of sample solution and reference solution were measured. The results show, that white mulberry has higher antioxidant components content as black mulberry