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Determination of selected chemical parameters of fruit of new currant varieties
Pelikánová, Blanka ; Diviš, Pavel (referee) ; Vespalcová, Milena (advisor)
Presented diploma thesis is dedicated to the determination of selected chemical parameters of fruits of new currant varieties. The theoretical part is focused on the characteristics of currant, the biologically active substances of its fruits and also the utilization of current in the food industry. Further part of the theory deals with the main chemical parameters which were examined: polyphenols, anthocyanins, ascorbic acid and antioxidant activity. In the practical part there were determined selected chemical parameters in six white, twelve red and thirteen black varieties of currant. Anthocyanins and polyphenols have been determined spectrophotometrically. The content of ascorbic acid in selected varieties of currant was determined by HPLC. As a technique for the determinationof the antioxidant activity was selected the method of free radical DPPH.
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Pretreatment of hops for further processing in beer technology
Tichá, Anna ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deals with pre-treatment of hops for further processing in beer technology. In the experimental part of the work, the effect of low temperatures, as pre-treatment of hops, on the monitored parameters was observed. Three types of cold pretreatment were used. In two cases, the hop material was frozen using a freezer at -25 ° C and in the second case at -70 ° C. In the third case, the hop material was treated by contact with liquid nitrogen in combination with mechanical treatment. The variety of hop materiál was Žatecký poloraný červeňák, which were in the form of pellets or pressed hop cones. The total bitterness of the samples, the total content of phenolic substances, the total content of flavonoids, the antioxidant activity and the concentration of essential oils, specifically myrcene humulene and geraniol, were examined. The effect of pre-treatment was investigated during conventional worth boiling as well as dryhopping. The experimental part includes descriptions of the hopping process, descriptions of individual analytical methods. A parallel measurement was performed on each sample. Significant advantages or disadvantages of some of the pretreatments were not demonstrable, however, the most significant differences were observed in samples hopped with hops pretreated by freezing at -70 ° C, which had a positive effect on the amount of extracted essential oils during cold hops.
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Study of qualitative parameters of fruit juices and possibilities of their modification via technological modifications
Fajtl, Zdeněk ; Omelka, Ladislav (referee) ; Polovka, Martin (advisor)
Ovocné šťávy jsou celosvětově nejoblíbenějšími nealkoholickými nápoji. Kromě vitamínů a minerálů jsou také bohatým zdrojem polyfenolů, které jsou považovány za látky přispívající k celkové antioxidační aktivitě. Zvyšující se požadavky konzumentů na kvalitu a bezpečnost potravin nutí výrobce k zvyšování výrobních a kvalitativních standardů potravin. Nedávné inovace ve výrobě ovocných šťáv vedly k modifikacím výrobních podmínek, které zahrnují změny ve složení šťávy (např. přídavek ovocné dužiny nebo malých ovocných kousků), vylepšování vlastností obalových materiálů a modifikace produkční atmosféry. Cílem diplomové práce bylo pomocí metod EPR a UV-VIS spektroskopie posoudit vliv různých výrobních postupů na vybrané kvalitativní znaky (antioxidační aktivita, změna barvy a koncentrace vybraných fytochemikálií) pomerančových šťáv s dužinou a ananasových šťáv, a charakterizovat jejich změny v průběhu dlouhodobého skladování. Získané výsledky byly zpracovány metodami multivariační statistické analýzy s cílem posoudit vliv původu suroviny, roku produkce a použitých výrobních podmínek na sledované parametry a celkovou kvalitu ovocných džusů. Výsledky jasně prokázaly, že pasterizace ovlivňuje kvalitu výrobku; ačkoli byla použita „šetrná“ pasterizace, byl u těchto vzorků pozorován mírný pokles prakticky všech monitorovaných parametrů v porovnání s čerstvými – nepasterizovanými šťávami. Avšak pokud jde o po-pasterizační změny, byl prokázán významný vliv produkční atmosféry na monitorované kvalitativní parametry šťáv, prokazující, že náhrada kyslíku inertními plyny může výrazně prodloužit trvanlivost šťáv. Kinetické studie změn sledovaných parametrů na době skladování ukazují, že ve většině případů dochází k postupnému zhoršování všech monitorovaných parametrů, a to bez ohledu na technologii zpracování šťávy. Ve vzorcích vyrobených použitím modifikované atmosféry bylo, v závislosti na typu inertního plynu, pozorováno zpomalení poklesu jednotlivých kvalitativních parametrů šťáv jako výsledek aplikace inertní atmosféry. Tento trend byl zřejmý především pro delší skladovací období, zatímco na začátku skladování (6 - 7 týdnů po výrobě dané šťávy) byly pozorované trendy nejednoznačné. Lze proto předpokládat že tento „ochranný“ efekt inertní atmosféry je ovlivňován fyzikálně-chemickými vlastnostmi jednotlivých plynů, zejména jejich rozpustností v kapalném médiu. Výsledky také prokázaly že vlastnosti šťáv jsou ,bez ohledu na druh ovoce, výrazně ovlivňovány také sezónními vlivy a původem surové šťávy. Z výsledků statistické analýzy vyplývá, že rok výroby je silným diskriminačním faktorem. Na základě všech monitorovaných charakteristik, bylo dosaženo absolutní diskriminace vzorků pomocí kanonické diskriminační analýzy. Pokud jde o původ surovin, byla dosažena pouze částečná diferenciace, i když s poměrně vysokým klasifikačním skóre. Pokud jde o technologii výroby, byla dosažena pouze částečná diferenciace vzorků podle typu použitého inertního plynu. Získané poznatky pomohou výrobcům ovocných šťáv s optimalizací výrobních podmínek s cílem získat výrobek s maximem prospěšných vlastností, které by si udržel po celou dobu expirace, jejíž délka může být také optimalizovány na základě prezentovaných výsledků.
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Study of natural antimicrobial mixtures and their stabilization
Vejrostová, Petra ; Veselá, Mária (referee) ; Márová, Ivana (advisor)
Present diploma thesis is focused on natural antimicrobial substances. The aim of the experimental part of thesis was testing of antimicrobial activity of selected natural substances in free and encapsulated forms, preparation of particles and monitoring of their long-term stability. Various teas extracts (aqueous, ethanoic and DMSO) and aqueous herbs extracts were used as plant antimicrobial substances. Liposomes and chitosan particles with encapsulated aqueous teas extracts were prepared by ultrasonication. Encapsulation efficiency, size, stability and antioxidant activity for all particles were specified. Consequently, within a two months period, long-term stability for these particles was monitored. Spectrophotometric method for determining total polyphenols was used for evaluating encapsulation efficiency as well as for monitoring of long-term stability. The DLS method was used for determination of size and stability of particles. Antioxidation activity was monitored by using spectrophotometric method using ABTS. For testing antimicrobial activity of various types of teas, herbs extracts and their mixtures and combianitons with lysozyme and antibiotics, broth dilution methods were used while using both Gram positive and Gram negative bacterial test strains. Antimicrobial activity of prepared particles was also monitored, the antimicrobial activity was especially significant with the chitosan particles. Suitable combinations of natural substances whatever with antimicrobial or antioxidation effect either in free or encapsulated form could be used for applications for example in cosmetics industry, food processing or in medicine.
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Analysis of biologically active substances in apricot oil
Valasová, Denisa ; Márová, Ivana (referee) ; Němcová, Andrea (advisor)
The Master’s thesis is focused on the analysis of biologically active substances in apricot kernel oil. Apricot oil has recently begun to be widely used in the cosmetics industry, particularly as a part of massage oils or as part of moisturizing creams. The aim of this thesis is to characterize and assess the quality of apricot oil, determination of the content of selected active ingredients, through a series of analytical methods, and subsequent use of this oil in cosmetics and food industry. The thesis is based on the comparison of the quality of pure apricot oil and the oil after the fermentation process. It has been found that apricot kernel oil actually contains large amounts of unsaturated fatty acids. The excellent antioxidant activity of apricot kernels was proven too, especially those after fermentation. In addition to antioxidant activity, the samples contain a relatively large amount of tocopherol after the fermentation. Tocopherol is important for the uptake of free radicals in lipid bilayers, thus slowing down aging, protect the membranes and also prevent from possible cardiovascular and oncological diseases. Furthermore, in the Master’s thesis there were confirmed not only the hydration effects of creams with apricot oil, but also their ability of inhibic transepidermal loss of water from the epidermis. Creams were tested on five probands, aged 23–24, with different skin types. After the application of creams to their skin, these properties greatly improved, the skin has been regenerated and hydrated for 24 hours after the treatment.
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Biological effects of various hemp fractions
Vacková, Hana ; Skoumalová, Petra (referee) ; Němcová, Andrea (advisor)
Cannabis is the only plant which contains cannabinoids and thanks to these compounds it has enormous potential. This thesis deals with the analysis of technical hemp. Effects of cannabinoids and methods used for cannabis analysis are discussed in the theoretical part. The experimental part includes spectrophotometric characterization of cannabis, it´s antimicrobial effects and thin layer chromatography analysis. Three sorts of Cannabis sativa L. were analyzed, namely Finola, Fedora and Kompolti. Firstly, the content of polyphenols, flavonoids and antioxidant activity in prepared tinctures were determined. Moreover, antimicrobial test were performed using disk test and turbidity determination. Gram-positive and Gram-negative bacteria and yeast organism were tested. It was found that cannabis tinctures possess good antimicrobial effects. Some of them are comparable with synthetic antibiotics. Finally, thin layer chromatography enabled visualization of cannabinoids in prepared tinctures.
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Characterization of blackthorn products
Červinková, Zuzana ; Veselá, Mária (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis deals with the preparation and the chemical characterization of ethanolic extracts and products from the blackthorn (Prunus spinosa L.) fruit. The theoretical part of the work contains the characterization of the blackthorn and describes the chemical composition of the fruit. Furthermore, the theoretical part states possible effects and possible uses of the Prunus spinosa L. fruit in the food industry, folk medicine and pharmacy. The experimental part describes the preparation of the extracts (40% ethanol) and the products (i.e., homemade sloe wine and homemade blackthorn liqueur). The content of reducing sugars, polyphenols and flavonoids was quantified in samples of wine, liqueur, juice and ethanol extracts. Furthermore, the antioxidant activity of individual samples was determined. Two spectrophotometric methods for the determination of reducing sugars were used and compared, namely the Somogyi-Nelson (SN) assay and the 3,5-dinitrosalicylic acid (DNS) assay. The DNS assay provided slightly overestimated results, while the results from the SN assay were closer to the actual content of reducing sugars. Polyphenols and flavonoids are substances that have antioxidant properties. A strong correlation was observed between antioxidant activity and the concentration of flavonoids.
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Study of the antioxidative potential of selected fruit marcs
Havlíčková, Barbora ; Zemanová, Jana (referee) ; Vespalcová, Milena (advisor)
Subject of this bachelor thesis was antioxidant activity of selected kind of fruits. Among selected kinds were the marc of red and white grapes, moldings from red elderberry and aronia. Two species of made capsules from marcs of white grapes and aronia were also subjected to analysis. Results of this bachelor thesis are summarized to four chapters. The first chapter compares the water content of drying at 40 ° C and 105 ° C. In the second chapter, the results of extraction in different proportions of solvent mixture ethanol - water and results of extraction in prepared artificial gastric juice are discussed. As a result, the water – ethanol mixture was a more effective solvent than artificial gastric juice. The third chapter deals with the results and discussion of the determination of the total content of phenolic substances. For the solvent mixture, the largest amount of polyphenols in the red vine marc was determined to be 43,56 mg.g-1, while in gastric juice the largest content in the elderberry was determined to be 11,89 mg.g-1. Capsules were also extracted in gastric juice, and 2,53 mg.g-1 was found in aronia tablets, while 5,93 mg.g-1 in white grape tablets. The last chapter compares the results of TAA measurements using the TEAC and EPR methods. The EPR method was more suitable for much diluted solutions than the TEAC method. The results of this work show that there is a large number of polyphenols and other antioxidants in the moldings that affect the overall antioxidant activity. Marcs have great potential for use as natural dyes or can be used to make a food supplement.
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Isolation and characterizaation of oil from some types of coffee
Vašků, Barbora ; Hoová, Julie (referee) ; Skoumalová, Petra (advisor)
Coffee, extract, oil, phenolic compounds, flavonoids, antioxidant capacity, SPF, critical wavelenght.
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In vitro study of antioxidant activity of food supplements
Vopelková, Dominika ; Pořízka, Jaromír (referee) ; Omelka, Ladislav (advisor)
Bachelor thesis deals with the determination of antioxidant activity of food supplements in vitro. The theoretical part focuses on legislative requirements of food supplements, their characteristic and classification. Further, the attention is also devoted to antioxidants, their properties, effects, importance and utilization. Separate chapter describes herbs, which are an essential component of researched supplements, their effects and properties. For experimental part several food supplements in various forms (capsule, tea, juice, dried fruits) were chosen and total content of polyphenols was determined using the UV-VIS spectroscopy. Further, the total antioxidant activity is characterized by electron paramagnetic resonance involving DPPH method.
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