Ekstrakcija kofeina iz čajeva ekološki prihvatljivim otapalima

master's thesis

• Title (english): Caffeine extraction from different teas with eco-friendly solvents
• Author: Ivana Špiljak
• Mentor: Aleksandra Sander (mentor)
• Committee member: Aleksandra Sander (predsjednik povjerenstva)
• Committee member: Jasna Prlić Kardum (član povjerenstva)
• Committee member: Irena Škorić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2022-09-30, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Posljednjih se godina sve veća pozornost pridaje novim ekološki prihvatljivim alternativama konvencionalnim otapalima za ekstrakciju. Veliku pozornost u tom kontekstu privukla su niskotemperaturna eutektička otapala (DES-Deep eutectic solvents). Cilj ovog rada bio je pridonijeti boljem poznavanju djelovanja DES-ova i njihovih svojstava. U ovom radu istražena je efikasnost DES-ova u procesu ekstrakcije kofeina iz tri vrste čaja (crni, zeleni i yerba mate). Crni i zeleni čaj potječu od biljke Camellia sinensis, a yerba mate čaj se dobiva od lišća južnoafričke biljke Ilex paraguariensis. Navedene vrste čaja sadrže značajne količine kofeina koje se ekstrahiraju uz pomoć DES-ova. Pripravljena su četiri DES-a s različitim udjelima vode: DES1 na bazi kolin-klorida i limunske kiseline u molarnom omjeru 2:1 s 30 % vode; DES2 na bazi jabučne kiseline, glukoze i glicerola u molarnom omjeru 1:1:1 s 30 % vode; DES3 na bazi mliječne kiseline i glicerola u molarnom omjeru 2:1 s 10 % vode i DES4 na bazi kolin-klorida i jabučne kiseline u molarnom omjeru 1:1 s 30 % vode. Modelom COSMO-RS procijenjena je topljivost kofeina u navedenim otapalima te raste u slijedećem smjeru: DES2 > DES3 > DES 4 > DES1. Pomoću pripremljenih otapala provedena je šaržna ekstrakcija pri sobnoj temperaturi uz stalan maseni omjer listića čaja i otapala. Koncentracija kofeina u ekstraktima određena je primjenom UV/Vis spektroskopije. Otapalo DES2 pokazalo se kao najefikasnije za ekstrakciju kofeina zelenog i crnog čaja, a za yerba mate čaj najveću efikasnost je pokazalo otapalo DES1. Najmanje efikasnim pokazalo se otapalo DES1 za crni i zeleni čaj, a za yerba mate DES2. Eksperimentalno je određena i antimikrobna aktivnost (testom osjetljivosti) i toksičnost otapala (bakterijom Vibrio fischeri). Rezultati testova su pokazali kako je od svih ispitanih otapala DES3 najtoksičniji.

Abstract (english)

In recent years, increased attention has been focused on discovering environmentally acceptable alternatives to conventional extraction solvents. Among these environmentally friendly solvents, deep eutectic solvents (DES) are drawing the most attention. The aim of this work was to contribute to a better understanding of DESs and their properties. In this work, extraction efficiency of four DESs was investigated in the process of caffeine extraction from three types of tea (black, green and yerba mate). Black and green tea are derived from the Camellia sinensis plant, and yerba mate tea is obtained from the leaves of the South African plant Ilex paraguariensis. Four DESs with different water content were prepared: DES1 based on choline chloride and citric acid (2:1 molar ratio) with 30% water; DES2 based on malic acid, glucose and glycerol (1:1:1 molar ratio) with 30% water; DES3 based on lactic acid and glycerol (2:1 molar ratio) with 10% water and DES4 based on choline chloride and malic acid (1:1 molar ratio) with 30% water. The COSMO-RS model was used to estimate the solubility of caffeine in the solvents, and it increases in the following direction: DES2 > DES3 > DES 4 > DES1. Using the abovementioned DESs, batch extraction was carried out at room temperature with a constant tea leaves to solvent mass ratio. Caffeine concentration in the extracts was determined using UV/Vis spectroscopy. Solvent DES2 was the most effective for extracting caffeine from green and black tea, and DES1 for yerba mate tea. Solvent DES1 was the least efficient in extracting caffeine from black and green tea and DES2 for yerba mate. Antimicrobial activity of extracts and toxicity of solvents were experimentally determined with using sensitivity and Vibrio fischeri toxicity tests. The tests results showed that DES3 is the most toxic of all the solvents.

• Keywords: antimikrobna aktivnost; čaj; ekotoksičnost; ekstrakcija; kofein; niskotemperaturna eutektička otapala
• Keywords (english): antimicrobial activity; tea; ecotoxicity; extraction; caffeine; deep eutectic solvents
• Language: croatian
• URN:NBN: urn:nbn:hr:149:164019
• Study programme: Title: Environmental Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka ekoinženjerstva (magistar/magistra inženjer/inženjerka ekoinženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2023-03-31 10:02:44