Primjena visokonaponskog pražnjenja za ekstrakciju steviozida i rebaudiozida A iz stevije

master's thesis

• Title (english): Application of high-voltage discharges for extraction of stevioside and rebaudioside A from stevia
• Author: Mario Grđan
• Mentor: Zoran Herceg (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Food Engineering); (Laboratory for Food Processes Engineering); Zagreb
• Defense date and country: 2015-09-22, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Svrha ovog rada je utvrditi učinak plinske i tekućinske plazme na ekstrakciju steviozida i rebaudiozida A iz osušenog lišća stevije. Uzorci su tretirani uz tri nezavisne varijable - temperatura, protok i vrijeme kod plinske, odnosno temperatura, frekvencija i vrijeme kod tekućinske plazme, a za usporedbu je provedena ekstrakcija po Soxhletu. Eksperiment je dizajniran putem potpunog faktorijalnog plana, rezultati su obrađeni metodom odzivne površine (RSM), a steviozidi i rebaudiozidi su identificirani HPLC metodom. Oba tretmana plazmom ostvarila su u prosjeku 42% - 45% veći prinos od ekstrakcije po Soxhletu. Temperatura je kod plinske plazme imala značajan utjecaj na ekstrakciju dok drugi faktori kao i svi faktori kod tekućinske plazme nisu imali statistički značajan utjecaj. Došlo je do pada pH i porasta provodljivosti nakon obrade tekućinskom plazmom. Pretpostavlja se da mehanizam ekstrakcije uključuje elektroporaciju pod utjecajem pulsirajućeg električnog polja te oksidaciju biljnih stanica radikalima i vodikovim peroksidom uz djelovanje UV zračenja.

Abstract (english)

The purpose of this study is to determine the effect of gas-phase and liquid-phase plasma on extraction of stevioside and rebaudioside A from the dried leaves of Stevia. The samples were treated using three independent variables - temperature, flow, and time for gas-phase and temperature, frequency and time when using liquid-phase plasma. For comparison,Soxhlet extraction was carried out. The experiment was conducted using full factorial design, the results were analyzed with response surface methodology, and steviosides and rebaudiosides were identified by HPLC. Both plasma treatments achieved an average of 42% - 45% higher yield than the Soxhlet extraction. The temperature in the gas-phase plasma had a significant impact on the extraction while other factors as well all factors in liquid-phase plasma had no statistically significant effect. There was a drop in pH and an increase in conductivity after processing with liquid-phase plasma. It is assumed that the extraction mechanism includes electroporation under the influence of a pulsed electric field, oxidation of plant cells by radicals and hydrogen peroxyde , and UV radiation.

• Keywords: ekstrakcija; hladna plazma; visokonaponsko pražnjenje; steviozidi; stevija
• Keywords (english): extraction; cold plasma; high-voltage discharge; stevioside; stevia
• Language: croatian
• URN:NBN: urn:nbn:hr:159:425848
• Study programme: Title: Food Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka prehrambenog inženjerstva (magistar/magistra inženjer/inženjerka prehrambenog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-05-03 12:12:35