Utjecaj duljine trajanja ekstrakcije i hidrolize na polifenolni sastav i antioksidacijska svojstva biljnih infuzija

master's thesis

• Title (english): The effect of extraction time and hydrolysis on polyphenolic composition and antioxidative properties of herbal infusions
• Author: Marija Berendika
• Mentor: Draženka Komes (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Food Engineering); (Laboratory for Chemistry and Technology of Carbohydrates and Confectionery Products); Zagreb
• Defense date and country: 2010-07-13, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Biljne infuzije su posljednjih godina postale najpopularnije piće upravo zbog svog kemijskog sastava te vezano uz njega brojnih pozitivnih učinaka na zdravlje. Biljne infuzije imaju dugu tradiciju primjene u narodnoj medicini, a njihovi brojni pozitivni učinci sve više se potvrđuju rezultatima znanstvenih ispitivanja. U ovom radu ispitan je utjecaj duljine trajanja ekstrakcije vodom (5 i 15 minuta) i kiselinske hidrolize na udjel polifenolnih spojeva i antioksidacijski kapacitet šest biljnih ekstrakata: melisa, majčina dušica, list kupine, cvijet lavande, kopriva i list masline. Udjeli ukupnih fenola, neflavonoida, flavonoida, flavan-3-ola i tanina određeni su spektrofotometrijskim metodama, dok je primjenom tekućinske kromatografije visoke djelotvornosti (HPLC-PDA) određen udjel pojedinačnih fenolnih kiselina, flavona i flavonola. Antioksidacijska aktivnost ispitana je primjenom dvije metode: reakcijom s 2,2'-azino-bis(3-etilbenzotiazolin-6-sulfonska kiselina) radikalom (ABTS metoda) te reakcijom s željezo(III)-tripiridiltriazinom kompleksom (FRAP-metoda). Najveći udjel ukupnih fenola određen je u hidroliziranom ekstraktu lista kupine te u nehidroliziranom petnaestminutnom ekstraktu melise. Hidrolizirani ekstrakti kupine i melise imaju najveći antioksidacijski kapacitet, dok nehidrolizirani ekstrakt lista masline pokazuje najmanji udjel fenolnih spojeva i najmanji antioksidacijski kapacitet. Najveći udjel ružmarinske kiseline, kao najzastupljenijeg fenolnog spoja, određen je u nehidroliziranom ekstraktu melise nakon 15 minuta ekstrakcije. Konzumiranje ispitivanih biljnih infuzija predstavlja značajan doprinos svakodnevnom unosu bioaktivnih sastojaka u organizam.

Abstract (english)

Herbal infusions became one of the most popular beverages of the world, mainly due to chemical compounds it contains and numerous positive effects on human health. The positive effects of various herbal teas are well known in traditional medicine, and that is confirmed by numerous scientific researches. In this study the efficiency of extraction time with water (5 and 15 minutes) and acidic hydrolysis of six herbal extracts (lemon balm, thyme, blackberry leaves, lavander, nettle and olive leaves) were investigated to determine the content of total polyphenols and antioxidant capacity.The content of total phenols, non-flavonoids, flavonoids, flavan-3-ols and tannins was determined by using spectrophotometric methods, while the composition of individual phenolic acids, flavones and flavonols were determined by using high performance liquid chromatography (HPLCPDA). The extracts were screened for their potential antioxidant activities using two different assays: reactions with 2,2`-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS assay) and Ferric reducing antioxidant power (FRAP assay). The highest content of phenolic compounds was determined in hydrolized extract of blackberry leaves and in the non-hydrolized (15 min) extract of lemon balm obtained after 15 minutes of extraction. They also exhibited the highest antioxidant capacity, while extracts of olive leaves were characterized with the lowest content of phenolic compounds and antioxidant capacity.The highest content of rosmarinic acid, as the most abundant phenolic compound, was determined in non-hydrolized extract of lemon balm, obtained after 15 minutes of extraction. Examined herbal infusions showed to be a valuable supplement to a daily intake of bioactive compounds.

• Keywords: antioksidacijski kapacitet; biljni čaj; polifenoli; tanini; HPLC
• Keywords (english): antioxidant capacity; herbal tea; polyphenols; tannins; HPLC
• Language: croatian
• URN:NBN: urn:nbn:hr:159:259468
• Study programme: Title: Food Technology; specializations in: Food Engineering; Course: Food Engineering; Study programme type: university; Study level: graduate; Academic / professional title: diplomirani inženjer prehrambene tehnologije; smjer prehrambeno inženjerstvo (diplomirani inženjer prehrambene tehnologije; smjer prehrambeno inženjerstvo)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-08-25 12:27:33