Stabilnost kurkuminoidov v subkritični vodi

določanje mehanizmov in hitrost reakcij razgradnje

Tina Zorec (Author), Mojca Škerget (Mentor), Željko Knez (Co-mentor)

Abstract

Kurkuma je začimba, zlato rumene barve, ki se pridobiva iz korenine rastline Curcuma longa L. Po tradicionalni vzhodni medicini so zdravilni učinki kurkume čiščenje krvi in prebavil, pomaga pri težavah z jetri in žolčnikom in pri hepatitisu. Ščiti jetra pred raznimi strupi in kemikalijami, je učinkovita pri zdravljenju virusnega hepatitisa in izboljšuje izločanje zaščitnih snovi v želodcu, ki ščitijo želodčno steno. Deluje protivnetno, kot antioksidant ter kemopreventivno. Kurkuma vsebuje fenolne spojine imenovane kurkuminoide, kateri dajejo rumeno oranžno barvo kurkumi in prav to naj bi bilo njena glavna zdravilna učinkovina. Kurkuma se v veliki meri uporablja tudi v živilstvu, kot barvilo ali začimba. Namen diplomskega dela je bil preučiti vpliv temperature na razgradnjo kurkuminoidov v subkritični vodi. Pri izvajanju eksperimentalnega dela diplomske naloge nas je zanimala maksimalna temperatura pri kateri so kurkuminoidi še stabilni. Preučili smo hitrost razgradnje posameznih kurkuminoidov v tem mediju. Prav tako smo preučili tudi reakcijski mehanizem razgradnje, torej razgradne produkte kurkuminoidov ter le te skušali kvantificirati. Eksperimente smo izvajali v laboratorijskem visoko-tlačnem visoko-temperaturnem avtoklavu (Andreas Hofer Hochdrucktechnik) pri subkritičnih pogojih vode. Spremljali smo vpliv temperature pri različnih reakcijskih časih. Ugotovili smo da se z višanjem temperature pri reakciji stabilnost kurkuminoidov manjša. Rezultati kažejo da so kurkuminoidi stabilni pri višjih temperaturah, pri temperaturi 180 °C pa močno razpadejo. Spremeni se njihova barva in s tem predvidevamo da razpadejo tudi zdravilne učinkovine ter nastaja vse več produktov razgradnje. Vzorce iz reaktorja smo analizirali s HPLC metodo in skušali kvalitativno kot tudi kvantitativno določiti produkte hidrotermične degradacije. V diplomskem delu je prikazan mehanizem degradacije kurkuminoidov in njihovih produktov. Naprej razpadejo na hidroksicinamične kisline, nato na vanilin, 4-hidroksibenzaldehid in še različne druge produkte, katerih nismo posebej obravnavali. Topnost kurkuminoidov v vodi je zelo slaba, zato prihaja tudi do manjših odstopanj in nihanj pri prikazu kinetičnega modela in časovne odvisnosti koncentracije komponent. Pri temperaturi 100 °C ni bilo mogoče prikazati kinetike razgradnje zaradi zelo slabe topnosti v vodi. Pri analizah smo uporabili kinetični model 1.reda in ugotovili, da je degradacija kurkuminoidov pri višjih temperaturah hitrejša kot pri nižjih.

Keywords

kurkuminoidi;subkritična voda;hidrotermična degradacija;visokotlačna tekočinska kromatografija;diplomske naloge;

Data

Language:	Slovenian
Year of publishing:	2016
Typology:	2.11 - Undergraduate Thesis
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher:	[T. Zorec]
UDC:	543.544.5:547.979.4(043.2)
COBISS:	20371990
Views:	1062
Downloads:	144
Average score:	0 (0 votes)
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Other data

Secondary language:	English
Secondary title:	Stability of curcuminoids in subcritical water: Determination of mechanisms of degradation and degradation rate
Secondary abstract:	Turmeric is a spice of golden yellow colour, which is extracted from a root plant Curcuma longa L. In traditional eastern medicine turmeric is known for healing effects in blood cleaning and digestive system, it helps with liver and gall bladder problems and with hepatitis. It protects liver against various poisons and chemicals, it is efficient in healing of the viral hepatitis and it improves secretion of protective substances that protect stomach wall. It has anti-inflammatory effect as antioxidant and has chemo preventive effect. Turmeric consists of phenolic compound so called curcuminoids which give yellow orange pigment in turmeric and exactly this is supposed to be the main healing effect. Turmeric is broadly used in food technology as pigment or as a spice. The aim of diploma thesis is to study the influence of temperature on curcuminoids decomposition in subcritical water. The objective is to determine the maximum temperature, where curcuminoids are still stable. Furtheremore, the decomposition speed of the individual curcuminoids in this media has also been studied. The reaction mechanism of decomposition has been studied as well and the main decomposition products were quantified. Experiments were carried out in laboratory high-pressure high-temperature autoclave (Andreas Hofer Hochdrucktechnik) at subcritical water conditions. The influence of temperature at different reaction times was observed. It was observed that with temperature rise the stability of curcuminoids is decreasing. Curcuminoids are stable at higher temperatures, however at 180 °C they disintegrate firmly. Its colour is changed and we predict that consequently the healing effects disappears, more decomposition products are formed and the healing effects disappears samples were submitted to HPLC analysis and the products of hydrothermal degradation were analysed qualitatively and quantitatively. Degradation mechanism of curcuminoids and its products is presented in the thesis. First they degrade into hydroxy cinnamic acid, then into vanillin, 4-hydroxybenzaldehyde and then into other products, which were not treated separately. Solubility of curcuminoids in the water is very low; therefore it comes to slight deviations of kinetic model and concentration dependence of compounds on time. It was not possible to show kinetic of decomposition at the temperature of 100 °C due to very low solubility in the water. Kinetic model of the 1st order was used in the analysis and we found out that degradation of curcuminoids is faster at higher temperatures than at lower.
Secondary keywords:	curcuminoids;subcritical water;hydrothermal degradation;high pressure liquid chromatography;
URN:	URN:SI:UM:
Type (COBISS):	Bachelor thesis/paper
Thesis comment:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages:	X, 44 str.
ID:	9161619