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Džiovintų ir šviežių vynuogių odelių fenolinių junginių kiekio ir antiradikalinio aktyvumo nustatymas
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| dc.contributor.author | Venckus, Justinas | |
| dc.date.accessioned | 2019-06-20T07:31:47Z | |
| dc.date.available | 2019-06-20T07:31:47Z | |
| dc.date.issued | 2019-06-14 | |
| dc.identifier.uri | http://dspace.kaunokolegija.lt//handle/123456789/1642 | |
| dc.description | Grapes have been one of the most popular fruits in the world for many centuries. The increasing demand for these berries is linked to phenols which give the grapes particular antioxidant properties. This is the reason why there is an evident focus on the industrial wastes, containing residual phenolic compounds from the plant materials. A lot of grape pomace is produced in the course of wine-making and grape peels make up a major portion of the marc. In order to evaluate the health benefits of eating grape skins, it seems plausible to determine whether the colour of different grape varieties, the freshness and the drying process of grape peels affect the amount of phenolic compounds and the antioxidant activity of grape skins. The aim of the research is to determine the amount of phenolic compounds and the antiradical activity of dried and fresh grape peels. The objectives of the research: to describe the active phytochemicals found in grape peels, to determine the total amount of phenols of dried and fresh grape peels, to evaluate the antioxidant activity of dried and fresh grape peels. The methodology of the research: the phenols from the fresh and dried grape skin samples of different grape varieties (white – Himrod, red – Red globe, blue – Merlot) were extracted by maceration over different time intervals (5, 10, 15, 20, 25, 30 min.) using distilled water. The total amount of phenolic compounds of fresh and dried grape peels was analyzed by Folin-Ciocalteu‘s colorimetry using a spectrophotometer and expressed in gallic acid equivalents (GAE) per one gram of grape peels. The antioxidant activity of fresh and dried grape skins was evaluated by DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging method. The results of the research: the smallest presence of phenols and the antioxidant activity were determined in the Himrod grape skin samples. The total amount of phenols in fresh white grape peels ranged from 1,87 to 2,20 mg/g. The antioxidant activity of white grape peels ranged from 50,92 to 56,83 percent. The largest total amount of phenolic compounds was found in the fresh Merlot grape skin samples and ranged from 2,91 to 3,33 mg/g. Moreover, these samples had the largest antioxidant activity which ranged from 66,90 to 71,52 percent. The total amount of phenols in the dried samples of white Himrod grape skins decreased on average by 18,54 percent (Red globe – 19,34 percent; Merlot – 15,17 percent). The antioxidant activity of dried white grape peels decreased on average by 5,03 percent (Red globe – 4,91 percent, Merlot – 6,14 percent). The conclusion: the main phenolic compounds found in grape peels are anthocyanins, myricetin, quercetin, kaempferol, resveratrol, ellagic acids, which act as chelants, inhibits certain oxidases and protects other active compounds from oxidative stress. It was established that dried grape skins had a smaller amount of phenols as well as an antioxidant activity than fresh grape peels | en_US |
| dc.description.abstract | Darbo turinį sudaro įvadas, literatūros analizė, empirinio tyrimo metodika ir rezultatų analizė, išvados, rekomendacijos, literatūra, priedai. Darbo apimtis – 42 psl., jame pateikta 13 paveikslų, 4 lentelės, 94 literatūros šaltiniai, 21 priedas (paskutinis priedas – akademinio sąžiningumo deklaracija). Analitinėje darbo dalyje atskleidžiama mokslinės literatūros analizė išskiriant vynuogių odelėse esančius fitokomponentus, aprašant jų biologinį aktyvumą, poveikį žmogaus sveikatai. Bendras džiovintų ir šviežių vynuogių odelių fenolinių junginių kiekis nustatytas Folin-Ciocalteu kolorimetriniu metodu, o antiradikalinis aktyvumas – 2,2-difenil-1-pikrilhidrazilo radikalo surišimo metodu. Nustatyta, kad džiovintos vynuogių odelės pasižymėjo mažesniu fenolinių junginių kiekiu ir antiradikaliniu aktyvumu nei švieži egzokarpai. Mažiausią fenolinių junginių kiekį ir antiradikalinį aktyvumą turėjo žaliųjų, o didžiausią – mėlynųjų vynuogių odelės | en_US |
| dc.language.iso | other | en_US |
| dc.subject | Vynuogės, odelė, fenoliniai, antiradikalinis, aktyvumas | en_US |
| dc.title | Džiovintų ir šviežių vynuogių odelių fenolinių junginių kiekio ir antiradikalinio aktyvumo nustatymas | en_US |
| dc.title.alternative | Determination of Phenol Compounds Content and Antiradical Activity of Dried and Fresh Grape Skins | en_US |
| dc.type | Other | en_US |
