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Master's Thesis
Author of thesis: Bc. Vendula Šmídová
Acad. year: 2025/2026
Supervisor: doc. Ing. Eva Vítová, Ph.D.
Reviewer: Ing. Jana Zemanová, Ph.D.
The aim of this Master’s thesis was to optimize the production process of jelly confectionery with the addition of grape pomace flour (Vitis vinifera) and its extract and subsequently characterize these products in terms of volatile organic compound content, total phenolic and anthocyanin content, antioxidant activity, and sensory quality. The determination of volatile compounds was performed using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. Bioactive compounds were determined using standard spectrophotometric methods. The total phenolic content was determined using the Folin-Ciocalteu reagent, antioxidant activity was determined by the TEAC method, and total anthocyanin content was determined by the pH differential method. Sensory analysis utilized unstructured graphical scales and ranking test. Based on the optimization of the grape pomace flour extraction process, which was guided by the total phenolic content, the following optimal conditions were selected: a temperature of 50 °C, 30 minutes of ultrasound assisted extraction, and a total of 75 minutes of maceration in a 75% ethanol solution with solid-to-solvent ratio of 1 g of grape pomace flour per 5 mL of solvent. Sensory analysis revealed that a 4% addition of the extract to jelly confectionery was the most suitable application of the plant material. This confectionery sample exhibited the same overall acceptability as the confectionery sample containing synthetic additives. In the confectionery sample with a 4% extract addition, 6 volatile compounds were identified. The highest proportions were represented by furfural (48,31%), 2-ethylhexan-1-ol (19,60%), ethyl-lactate (18,91%), nonanal (6,65%), and furfuryl alcohol (6,53%). Regarding bioactive compounds, the following values were determined: TPC 5222,99 ± 451 μgGAE g-1 ; TAA 1351,86 ± 218 μgTEAC ⸱ g-1; TAC 675,07 ± 53,18 μgC3G ⸱ g-1. In the confectionery sample with synthetic additives, 11 volatile compounds were identified. The highest proportions were represented by methyl anthranilate (73,18%) and propylene glycol (20,00%). The bioactive compound content was: TPC 1970,57 ± 206 μgGAE ⸱ g-1; TAA 390,97 ± 56 μgTEAC ⸱ g-1; TAC 20,81 ± 33,44 μgC3G ⸱ g-1. The addition of the extract to the confectionery, as well as direct addition of grape pomace flour, had a significant impact on both the bioactive and volatile compound content of the confectionery.
jelly confectionery, Vitis vinifera, volatile compounds, antioxidants, sensory analysis, SPME, GC-MS
Date of defence
29.05.2026
Result of the defence
Defended (thesis was successfully defended)
Grading
C
Process of defence
1. Studentka seznámila členy komise s náplní a cílem diplomové práce. 2. Byly přečteny posudky na diplomovou práci. 3. Studentka akceptovala všechny připomínky oponentky a na všechny otázky odpověděla v plné šíři. Diskuse: prof. RNDr. Ivana Márová, CSc. Zmiňujete metodu CCD, můžete ji objasnit? Jaké by byly podmínky skladování? Máte představu, jaká je skladovatelnost? K čemu slouží moučka z výlisků? prof. RNDr. Iva Burešová, Ph.D. Bylo by možné jednotlivé parametry extrakce vzájemně kombinovat? Jak byly zvolený optimální podmínky? Jsou tyto rozdíly významné? Jaké látky se používají jako konzervanty do želé cukrovinek? prof. Mgr. Václav Brázda, Ph.D. Jak jste získávali moučku z výlisků? Jedno se o komerční produkt? Studentka odpověděla na všechny doplňující otázky členů komise, které byly v průběhu diskuse k dané problematice vzneseny. Diplomantka prokázala dobré odborné znalosti i schopnost samostatné prezentace dosažených výsledků.
Language of thesis
Czech
Faculty
Fakulta chemická
Department
Institute of Food Science and Biotechnology
Study programme
Chemistry of Natural Products (NPCP_CHPL)
Composition of Committee
prof. RNDr. Ivana Márová, CSc. (předseda) prof. Ing. Stanislav Obruča, Ph.D. (místopředseda) doc. Ing. Pavel Diviš, Ph.D. (člen) doc. Ing. Eva Vítová, Ph.D. (člen) prof. RNDr. Iva Burešová, Ph.D. (člen) prof. Mgr. Václav Brázda, Ph.D. (člen)
Supervisor’s reportdoc. Ing. Eva Vítová, Ph.D.
Grade proposed by supervisor: C
Reviewer’s reportIng. Jana Zemanová, Ph.D.
Grade proposed by reviewer: B
Responsibility: Mgr. et Mgr. Hana Odstrčilová