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1.
RAZVOJ PRODUKTOV NA OSNOVI ANTIOCIANINOV
Tünde Vatai, 2009, dissertation

Abstract: Antocianini so skupina polifenolov, ki so odgovorni za barvno raznolikost cvetov in sadežev, od rumene, oranžne, rdeče, roza, do modre. V primerjavi s sintetičnimi barvili so nestabilni, kar predstavlja glavni problem pri njihovi uporabi in se lahko pokaže kot sprememba barve med procesiranjem in skladiščenjem. Glavni cilj doktorske disertacije je bil razviti produkt, naravno barvilo na osnovi antocianinov, ki bo ustrezno stabilen in bo predstavljal alternativo sintetičnim barvilom za uporabo v prehrambeni in farmacevtski industriji. Raziskovalno delo zajema študij ekstrakcije antocianinov iz grozdnih tropin, ki so stranski produkt v proizvodnji vina in predstavljajo potencialni vir naravnih barvil. V raziskavah smo uporabili tropine treh tradicionalnih sort rdečega grozdja, ki se pridelujejo v Sloveniji. Za primerjavo so bili eksperimenti narejeni tudi z uporabo svežega materiala – bezgovih jagod. Namen raziskav je bil določiti optimalne ekstrakcijske pogoje. Izvedla se je študija vpliva naslednjih parametrov: vrste in koncentracije topila za ekstrakcijo ter temperature. Študirali smo vpliv pH topila za ekstrakcijo na izkoristek in degradacijo antocianinov. Opazovali smo stabilnost dobljenih ekstraktov med skladiščenjem. Raziskali smo vpliv predobdelave naravnega materiala s superkritično ekstrakcijo s CO2. Poznano je, da ko-pigmenti vplivajo na stabilnost in barvo antocianinov, zato smo v dobljenih ekstraktih analizirali tudi vsebnost nekaterih flavonoidov. Drugi sklop raziskav v okviru doktorske disertacije zajema študij stabilizacije in formulacije antocianinov z uporabo visokotlačnih tehnologij s superkritičnimi fluidi (SCF). Raziskali smo naslednje SCF tehnike za formulacijo produkta: CPF™ (Concentrated Powder Form; Koncentrirana praškasta oblika), PGSS™ (Particles from Gas Saturated Solution; Delci iz raztopin nasičenih s plinom), SAS (Supercritical Antisolvent Precipitation; Prekristalizacija z antitopilom). V raziskavah smo uporabili različne materiale na osnovi antocianinov (ekstrakte, sokove in koncentrate) ter različne nosilce, ki so uporabni v prehrambeni industriji. Izvedli smo analize barvnih lastnosti in stabilnosti barve med skladiščenjem dobljenih praškastih produktov.
Keywords: ekstrakcija, superkritični ogljikov dioksid, formulacija produktov, PGSS™, CPF™, SAS, naravna barvila, antocianini, stabilnost
Published: 12.03.2009; Views: 3940; Downloads: 296
.pdf Full text (5,77 MB)

2.
Extraction of phenolic compounds from elder berry and different grape marc varieties using organic solvents and/or supercritical carbon dioxide
Tünde Vatai, Mojca Škerget, Željko Knez, 2009, original scientific article

Abstract: Optimal operating conditions for the extraction of phenolic compounds from grape marc and elder berry have been investigated. The aim was to obtain extracts with high anthocyanin content, which show stability during storage and would be potentially interesting for commercial applications as natural colorants. For this purpose three varieties of grape marc, native to Slovenia (Refošk, Merlot and Cabernet), were studied. The results were compared with the extraction of elder berry, which is known for its high anthocyanin content. Single-step batch extractions were performed with ethanol, ethyl-acetate and acetone in different ratios with water. Temperatures of 20 °C, 40 °C and 60 °C were applied. Influence of the change in pH values of the extraction media was investigated regarding the yield and degradation of anthocyanins. Two-step extractions, combining supercritical fluid extractions (SFE) and conventional batch extractions, were applied. The most efficient conventional solvents in single-step extractions were mixtures of organic solvent and water at 60 °C. Pre-treatment of the natural material with supercritical CO2 (with or without ethanol as co-solvent) improved the extraction of polyphenols from the grape marc. This method provides an alternative to the pre-treatment of the plant materials, replacing toxic organic solvents (e.g. hexane). Acidified extraction media resulted in higher anthocyanin content in the extracts. However, the degradation of the anthocyanins during storage was higher, which led to the loss of the intensive colour. The addition of a commercially available rosemary extract to the extraction solvent improved the stability of the grape marc extract during storage.
Keywords: extraction, organic solvents, supercritical CO2, anthocyanins, grape marc, elder berry, natural colorant
Published: 01.06.2012; Views: 1050; Downloads: 73
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