Extraction of essential oils from ginger (Zingiber officinale)

Namen diplomske naloge je bil raziskati potencialne protimikrobne in antioksidativne učinke različnih ekstraktov, pridobljenih iz ingverja (Zingiber officinale), s ciljem potencialne uporabe naravnih izvlečkov v prehrambeni, farmacevtski, živilski in kozmetični industriji. Ekstrakte smo pridobili z različnimi metodami ekstrakcije s Soxhletovo metodo, ultrazvočno metodo in superkritično ekstrakcijo s CO2. Vse ekstrakcije smo izvajali dve uri. Pri Soxhletovi in ultrazvočni ekstrakciji smo uporabili različna topila, s ciljem prepoznati razliko med ekstrahiranimi komponentami s pomočjo polarnega in nepolarnega topila. Različne metode ekstrakcije in različna topila vplivajo na količino pridobljenega ekstrakta in na vsebnost komponent, ki jih ekstrakt vsebuje. Zanimal nas je izkoristek ekstrakcij in kvaliteta pridobljenih ekstraktov. Uporabili smo dve spektrofotometrični metodi radikalsko metodo DPPH za določanje antioksidativne aktivnosti ekstraktov in metodo za določanje vsebnosti totalnih fenolov. Za določevanje protimikrobnega učinka smo uporabili difuzijsko metodo z diski, protimikrobno delovanje smo testirali na grampozitivni bakteriji Staphylococcus aureus, gramnegativni bakteriji Escherichia coli in kvasovki Candida albicans. V diplomskem delu so prikazani rezultati ekstrakcij in analiznih metod, ki smo jih izvedli. Iz rezultatov je vidno, da je uporaba Soxhletove ekstrakcije in topila aceton najboljša izbira za dosego najvišjega izkoristka ekstrakcije. Antioksidativni potencial smo ovrednotili z DPPH metodo, s katero smo najvišji odstotek inhibicije opazili pri ekstraktu, pridobljenem s superkritično ekstrakcijo pri 135 bar. Najnižji odstotek inhibicije smo opazili pri obeh ekstraktih, pridobljenih s topilom heksan. Pri določevanju vsebnosti totalnih fenolov smo opazili najvišjo vsebnost v ekstraktu, pridobljenem z ultrazvočno ekstrakcijo, kjer smo kot topilo uporabili mešanico acetona in vode v razmerju 1:1. Najnižji delež vsebnosti totalnih fenolov smo opazili pri ekstraktoma, pridobljenima s topilom heksan kar sovpada z najnižjim antioksidativnim potencialom. Nekateri pridobljeni ekstrakti so delovali protimikrobno proti C. albicans in S. aureus, medtem ko proti E.coli noben ekstrakt ni pokazal protimikrobnega učinka. The purpose of the thesis was to research potential antimicrobial and antioxidant effects of different extracts from ginger (Zingiber officinale) with the aim of potential use of natural extracts in nutritional, pharmaceutical, food and cosmetic industry. The extracts were obtained by different extraction methods Soxhlet extraction, ultrasound extraction and supercritical CO2 extraction. Each extraction lasted two hours. We used different solvents by Soxhlet extraction and ultrasound extraction with the aim to get know the difference among extracted components by using polar and nonpolar solvent. Different extraction methods and different solvents have impact on the quantity of obtained extract and the content of extract components. We were interested in extractions efficiency and the quantity of obtained extracts. We used only two spectrophotometric methods DPPH radical method to determine antioxidant activity of extracts and the method to determine total phenolic content. We used disk diffusion method for determining antimicrobial efficiency, antimicrobial activity was tested on gram positive bacteria Staphylococcus aureus, gram negative bacteria Escherichia coli and Candida albicans yeast. In the thesis we show the results of extractions and analytical method that we derived. It is proved by the results that Soxhlet extraction and acetone as a solvent are the best choice to obtain the highest extraction efficiency. Antioxidant potential was determined by DPPH method which revealed the highest percentage of inhibition extract that has been obtained by supercritical extraction at 135 bar. The lowest percentage of inhibition was noticed in both extracts obtained by hexane as a solvent. By determining total phenolic content we noticed the highest content in the extract which was obtained by ultrasound extraction, there we used acetone-water mixture in the ratio 1:1. The lowest percentage of total phenolic content was in extracts obtained by hexane as a solvent, the reason lies in the lowest antioxidant potential. Some obtained extracts were antimicrobial against C. albicans and S. aureus, on the other hand no extract did not have antimicrobial effect on E.coli.