Novi hidrogel sistemi na bazi alginata i proteina za kontrolisano otpuštanje etarskih ulja
Novel hydrogel systems based on alginate and protein for controlled release of essential oils
Докторанд
Volić, Mina M.Ментор
Bugarski, BrankoЧланови комисије
Knežević-Jugović, ZoricaĐorđević, Verica B.
Pećinar, Ilinka
Balanč, Bojana
Метаподаци
Приказ свих података о дисертацијиСажетак
Etarska ulja predstavljaju smeše aromatičnih i lako isparljivih jedinjenja koja su poznata po
svojim lekovitim svojstvima, zbog čega se mogu primeniti u lečenju raznih bolesti.
Antimikrobna svojstva određenih vrsta etarskih ulja svrstavaju ih u alternativne izvore
antimikrobnih lekova. Međutim, izazov koji se odnosi na stabilnost ovih ulja u toku
proizvodnje i skladištenja ograničava njihovu širu primenu. Dodatno, usled promene pH
vrednosti u gastrointestinalnom traktu može doći do gubitka biološke aktivnosti ulja. U skladu
sa tim, velika pažnja se posvećuje zaštiti etarskih ulja u cilju obezbeđivanja njihove efikasnosti
na mestu delovanja.
U doktorskoj disertaciji prikazan je postupak pripreme novih hidrogel sistema na bazi
alginata i proteina soje za inkapsulaciju i kontrolisano otpuštanje etarskog ulja timijana
(Thymus vulgaris L.). Najpre je urađena karakterizacija emulzionih sistema, ispitivanjem
stabilnosti, odnosno praćenjem promene zeta potencijala (laserska difrakciona tehnika...),
određivanjem reoloških svojstava emulzija, a zatim i analizom strukturne organizacije
molekula na ulje/voda granici faza (Ramanova spektroskopija).
U drugom delu rada sintetisani su hidrogel sistemi sa inkapsuliranim etarskim uljem,
primenom tehnike elektrostatičke ekstruzije, a dodatno je urađena optimizacija postupka
inkapsulacije variranjem koncentracija alginata i proteina soje (SPI). Zatim, ispitivani su
dobijeni hidrogel sistemi u cilju određivanja interakcija između komponenata nosača, kao i
nosača i inkapsuliranog ulja. Takođe, analizirani su profili bubrenja, veličina i oblik (optička
mikroskopija) i površinska morfologija uzoraka (skenirajuća elektronska mikroskopija).
Primenom metode kompresije testirana su mehanička svojstva hidrogel sistema, pri čemu je
pokazano da povećanje koncentracija alginata i SPI ima pozitivan efekat na mehaničke
karakteristike hidrogelova. Analizom uticaja temperature na hidrogel sisteme, u opsegu 50 -
100 ℃, uočeno je značajno povećanje termičke stabilnosti inkapsuliranog ulja. Hidrogelovi na
bazi alginata i proteina su zatim ispitani u cilju procene efikasnosti inkapsulacije ukupnih
polifenola (spektrofotometrijskom metodom) i timola (tečnom hromatografijom pod visokim
pritiskom). Poseban deo rada posvećen je karakterizaciji sa aspekta potencijalne primene
dobijenih sistema za kontrolisano otpuštanje etarskog ulja u simuliranim uslovima
gastrointestinalnog trakta (pH, T, enzimi, soli), kao i analizi uticaja pomenutih uslova na
reološko ponašanje hidrogelova. Takođe, određena je antioksidativna (ABTS i CUPRAC
metode) i antimikrobna (mikrodiluciona metoda) aktivnost inkapsuliranog ulja.
Treći deo rada obuhvata optimizaciju i karakterizaciju alginat/protein/lecitin sistema.
Naime, sinergistički efekat proteina soje i lecitina na granici faza, potvrđen analizom stabilnosti
emulzija, obezbedio je povećanje efikasnosti inkapsulacije i sporije otpuštanje timola usimuliranom želudačnom fluidu. Dodatno, mehanička i termička stabilnost hidrogel sistema
su poboljšane dodatkom lipidnog emulgatora.
Dobijeni rezultati ukazuju na veliki potencijal alginat/SPI i alginat/SPI/lecitin sistema za
primenu u prehrambenoj i/ili farmaceutskoj industriji, sa posebnim akcentom na stabilnost i
kontrolisano otpuštanje etarskog ulja.
Essential oils are mixtures of aromatic and highly volatile compounds, which are known for
their healing properties, and therefore can be used to control infectious and non-infectious
diseases. The antimicrobial properties of some essential oils classify them as alternative sources
of antimicrobial drugs. However, the challenge regarding the stability of these oils during
production and storage limits their wider use. In addition, changes in pH values in the
gastrointestinal tract may lead to a loss of biological activity of oils. In recent years, increasing
attention has been paid to the protection of essential oils in order to ensure their efficiency at
the site of action.
The presented doctoral thesis offers an approach for the formulation of novel hydrogel
systems based on alginate and soy protein for encapsulation and controlled release of thyme
essential oil (Thymus vulgaris L.). Firstly, the emulsion characterization was performed by
examining the stability (Laser Difraction Tec...hniques) and rheological characteristics of
emulsions, as well as by analyzing the structural organization of molecules at the oil/water
interface (Raman spectroscopy).
In the second chapter of the dissertation, the hydrogel systems with encapsulated essential
oil were synthetized using electrostatic extrusion technique. The encapsulation technique was
further optimized using different concentrations of alginate and soy protein isolate (SPI). The
hydrogels were characterized to show the interactions between carrier components and/or
carrier-encapsulated oil (Fourier Transform Infrared spectroscopy). In addition, swelling
behavior, particle size and shape (optical microscopy) and surface morphology (scanning
electron microscopy) were analyzed.
The particular emphasis was put on mechanical properties of hydrogels, where an increase in
the concentration of alginate and soy protein had a positive impact on the mechanical
properties of the hydrogel systems. The analysis of the temperature effect on hydrogel systems,
in the range 50 - 100 ℃, showed a significant increase in the thermal stability of the
encapsulated oil. Hydrogels based on alginate and protein were further tested for
encapsulation efficiency of total polyphenols (spectrophotometric method) and thymol (liquid
chromatography under high pressure). Subsequent analyses were focused on monitoring of
the release kinetics in simulated conditions of the gastrointestinal tract (pH, T, enzymes, salts)
and influence of the mentioned conditions on the rheological behavior of hydrogels. The
antioxidant (ABTS and CUPRAC methods) and antimicrobial (microdilution method) activities
of the encapsulated oil were also examined.
The third chapter of the thesis was dedicated to the optimization and characterization of
alginate/protein/lecithin systems. Namely, the synergistic effect of soy protein and lecithin on
the interface, which was confirmed by analysis of emulsion stability, has improved carrierencapsulation efficiency and enabled slower release of thymol in the simulated gastric fluid. In
addition, the mechanical and thermal stabilities of the hydrogels are improved by the addition
of a lipid emulsifier.
Overall, the results of this study indicate a great potential of alginate/SPI and
alginate/SPI/lecitin systems for application in the food and/or pharmaceutical industry, with
special emphasis on the stability and controlled release of oils in simulated conditions of the
gastrointestinal tract.
Факултет:
Универзитет у Београду, Технолошко-металуршки факултетДатум одбране:
29-12-2020Пројекти:
- Развој нових инкапсулационих и ензимских технологија за производњу биокатализатора и биолошки активних компонената хране у циљу повећања њене конкурентности, квалитета и безбедности (RS-MESTD-Integrated and Interdisciplinary Research (IIR or III)-46010)