National Repository of Grey Literature 115 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Characterization of minor fruit varieties in terms of use in the food industry
Jurečková, Zuzana ; Vítová, Eva (referee) ; Golian, Jozef (referee) ; Diviš, Pavel (advisor)
The thesis deals with one group of small fruits, the genus Ribes, ie currants, and gooseberries. It assesses their physical and chemical parameters with respect to the possibility of use in these properties for the design of a new type of product – beverages. Titration, spectrometric and other methods were used for the evaluation of these properties. A total of fifteen of these methods were available (total juice yield, juice pH, total dry matter, soluble fruit dry matter, titratable acidity, formolic number, reducing carbohydrate content, D-glucose, D-fructose and sucrose content, total polyphenolic substance content, anthocyanins, vitamin C and total antioxidant capacity) and a total of nine analytes (copper, iron, magnesium, phosphorus, zinc, manganese, potassium, calcium and sodium) were selected for the determination of mineral elements. For two years (harvest 2014 and 2015), these parameters were monitored for color variants of currants (white, red and black) and gooseberries (green-fruited, yellow-fruited and red-fruited). A total of six white varieties were tested in the group of currants - Olin, Jantar, Primus, Blanka, Viktoria and Orion, eleven varieties of red currants - Junnifer, Jesan, Detvan, Rovada, Rubigo, J.V.Tets, Tatran, Losan, Kozolupský raný, Stanca, NŠLS 11/6 and eleven varieties of black currant varieties - Ometa, Démon, Triton, Ben Hope, Ruben, Ben Gairm, Ben Lomond, Moravia, Ben Conan, Fokus and Ceres. A total of five varieties of green-fruited gooseberries were tested - Zebín, Mucurines, Rixanta, Rodnik and Prima. Yellow-fruited gooseberries were available in four varieties - Lemon Giant, Invicta, Golden Fig and Darek. The red-fruited gooseberries included varieties - Rolonda, Alan, Karat, Karmen, Krasnoslawjanskij, Himnomacki Rot, Remarka, Tamara and Black Neguš. Using Tukey's test, an analysis was performed and by scoring individual varieties based on the results of individual analyzes, a list of recommended varieties was compiled for further work on the development of a new beverage. Unfortunately, in 2015 there were very few fruits of green-fruited and yellow-fruited gooseberries, so it was decided that the volume of fruit will fall on the testing of bioactive substances. Therefore, at the end of the work, it is not possible to objectively evaluate these varieties of gooseberries in the whole range of analyzes. Therefore, the point evaluation of varieties was based on the averages of individual varieties. The red-fruited varieties were available in full, and therefore a full evaluation could take place. The most significant differences between red gooseberry varieties were in the content of bioactive substances (the content of polyphenolic substances, anthocyanin dyes, and vitamin C) and antioxidant capacity. These results were provided to the food subject, which continued to work with these values. Based on this project, utility model No. PUV 2016-33171 and the resulting combined drink based on wine and fruit juice were developed.
The factors influencing sensory quality of processed cheese analogues
Sůkalová, Kateřina ; Kráčmar, Stanislav (referee) ; Diviš, Pavel (referee) ; Buňka,, František (advisor)
The presented thesis deals with the monitoring sensory quality of processed cheese analogues, focusing mainly on the taste (flavour) and related content of volatile (aroma active) substances. Model samples of analogues were produced by a standard procedure at Tomas Bata University in Zlín. The experimental part was divided into two experiments, which differed in the composition of model samples of analogues. In the first experiment, the traditional fat (butter) was completely replaced by selected vegetable fats (palm, coconut, mixed), in the second experiment only a part (1% w/w - expressed on the total weight of the sample) of butter was replaced by vegetable oils (apricot, flax seed, currant, grape seed). Solid phase microextraction in conjunction with gas chromatography with flame ionization detection was used to determine volatiles. Methods based on valid international standards were used to evaluate the sensory quality of samples, focusing mainly on flavor, namely evaluation using scales (ISO 4121), profile test (EN ISO 13299) and ranking test (ISO 8587). The aim of the work was to assess the effect of the addition of various vegetable fats/oils on the above parameters, at the same time their changes were monitored during 6 months of storage (at 6 ° C). The results showed that the vegetable oil used affects both the sensory quality and the content and composition of volatile substances of analogues. Significant differences between samples were mainly in taste, aroma and overall acceptability. The decreasing overall acceptability of the samples can be expressed in experiment I by the order: product with butter coconut palm mixed fat; in the case of experiment II: product with butter apricot = flax = grape currant oil. Mixed fat, currant and grape seed oil proved to be unsuitable for the production of analogues, on the contrary, analogues with coconut fat and apricot oil were evaluated best. Based on the results of sensory analyses, it was shown that the samples maintain a good sensory quality min. for 3 months while maintaining a low storage temperature ( 6 ° C). An analogue with coconut fat, whose taste, aroma and acceptability were rated as very good, and apricot oil, whose taste, aroma and acceptability were even rated as excellent, could enrich the food offer on the market.
Analysis of onion and garlic samples of different geographical origin
Korček, Jakub ; Mikulíková, Renata (referee) ; Diviš, Pavel (advisor)
Presented master thesis dealt with the analysis of garlic and onion samples and tried to find correlations between chemical composition and country of origin. The parameters examined were dry content, crude protein content, concentration of phenolic compunds, carbohydrate content (fructose, glucose), alliin content and concentration of selected elements (P, Mg, Ca, Na, K, Fe, Zn). Average content of dry matter of fresh samples was 35,84 ±2,12 g/100 g and of dehydrated samples was 90,61 ±2,90 g/100 g. Concentration of phenolic compounds was measured spectrophotometrically with Folin-Ciocault reagent. Average phenolic compounds content of samples was 0,1840 ±0,1286 GAE g/100 g. Crude protein content was measured by Kjeldahl method, and calculated from total nitrogen content. Carbohydrates were measured by HPLC-ELSD after hydrolysis of fructans. Average content of fructose of garlic samples was 57,014 ±0,863 g/100 g, of onion samples was 33,718 ±1,168 g/100 g. Average content of glucose of onion samples was 22,633 ±0,405 g/100 g. Alliin content was measured by HPLC-DAD method. Average alliin content of fresh samples was 4,644 ±0,446 g/100 g and of dehydrated samples was 1,962 ±0,180 g/100 g. Elemental analysis was conducted by ICP-OES method. Average concentration of selected elements was: P 2,15 ±0,11 mg/g, Mg 0,638 ±0,03 mg/g, Ca 1,246 ±0,05 mg/g, Na 0,550 ±0,08 mg/g, K 7,49 ±0,41 mg/g, Fe 79,3 ±6,16 mg/kg, Zn 11,4 ±3,33 mg/kg. Obtained data were statistically processed on significance level 0,05. Based on the principal components analysis, it was found, that the best parameters to differentiate samples from Czechia, Poland and Ukraine from other countries were content of nitrogen, phosphorus, magnesium, sodium and calcium. It was also discovered, that genus differences between onion and garlic have greater significance than geographical differences.
Determination of microelements by ICP-OES after extraction by DGT technique
Habartová, Aneta ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
This thesis is focused on determination of microelements (Cd, Co, Cu, Fe, Mn, Ni, Pb a Zn) in milk by optical emission spectrometry with inductively coupled plasma (ICP-OES) after extraction by Diffusion Gradients in Thin films technique (DGT) containing Chelex 100 resin gel and agarose diffusion gel. The optimalization of DGT in model metal solutions was verified by recommended basic tests. The performance of the DGT technique in the diluted milk matrix was verified. By DGT technique was determined only Zn in real milk matrix with concentration 3,74 ± 0,02 mg/l. The other microelements in the prepared eluate were at or below the limit of detection of the instrumental method. The obtained results were compared with the analysis of milk after microwave digestion by ICP-OES. However, these results were below the detection limit of the device too, only Zn with concentration 3,91 ± 0,16 mg/l was measured. For the future analysis of the selected microelements in milk by DGT technique, further optimization of the preconcentration technique is required, or use of a more sensitive instrumental method.
Monitoring of chemical changes in ground coffee stored in different ways
Lajtman, Roman ; Vítová, Eva (referee) ; Diviš, Pavel (advisor)
This diploma thesis deals with the monitoring of chemical changes in ground coffee stored in various containers and then it deals with the determination of water, moisture and aromatic profile of coffee in individual containers, namely a can, a paper bag, a bag with a polyethylene liner, a bag from low density polyethylene with aluminium liner (LDPE + Al) and a glass container. At the beginning of the experiment it was found that the water content in the coffee was 4.72 ± 0.10 % and the moisture content was 9.47 ± 0.01 %. After the original sample was measured, the coffee was poured into 5 packages. At the end of the experiment, a can was chosen as the most suitable package where the lowest water content was measured. The water content was determined to be 6.51 ± 0.11 % and the moisture content was 9.93 ± 0.01 %. However, the differences between the other packages, apart from the paper bag, were very small, and thus in general it can be said that the can, the LDPE + Al package, the bag with the PE liner and the glass container are suitable for storing ground coffee. A total of 44 aromatics were identified when determining the aromatic profile in coffee by HS-SPME-GC-MS. The most represented groups of substances were furans and pyrazines. During storage, there was some loss of substances due to 2 mechanisms. The first of them is evaporation and the second one is the oxidation reactions themselves. Most aromatic substances have evaporated / degraded in paper packaging, where this large decrease is related to its barrier properties. A glass container was chosen as the most suitable packaging with the least loss of aromatic substances.
Analysis of sweet peppers of different geographical origin
Fiala, Petr ; Mikulíková, Renata (referee) ; Diviš, Pavel (advisor)
The diploma thesis is focused on the determination of basic nutritional properties of 26 samples of ground pepper from different countries and evaluates, whether the chemical composition of ground pepper is affected by the geographical origin. The amount of 19 nutritional properties were determined by advanced analytical methodes (ICP-OES, HPLC DAD, HPLC ELSD) together with other laboratory techniques. Final results were statistically processed by the methods of analysis of variance (ANOVA), cluster analysis, principal component analysis (PCA) and discriminant analysis (DA). Statistical evaluation confirmed, that the chemical composition is affected by the geographical origin. Analysis of variance (ANOVA) determined 14 parameters to statistically differ (p
Preparation and characterization of protein concentrates from wheat bran
Hubačová, Klára ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
The diploma thesis deals with usage of wheat bran as a source of high-quality proteins. Every year mill industry produces large amounts of by-products. These by-products are constituted by wheat bran. There is a big effort to use these type of materials within a circular economy. Wheat bran contains about 14–18 % proteins which appears to be a good component for valorisation. It is possible to extract proteins from bran according to their behaviour in the range of pH. Proteins are soluble in alkaline pH and can be precipitated around their isoelectric point. The final treatment of precipitated proteins is lyophilisation. The next step is characterisation of the product. There are a few parameters to analyse: purity of the isolate, amino acid profile, composition of minerals, water contain etc. Interest in nutrition is on the rise not only by professional sportsman. This isolated product could serve as a potential protein supplement.
Study of geographical authenticity of Moravian white wines
Horáková, Kristýna ; Křikala, Jakub (referee) ; Diviš, Pavel (advisor)
The aim of this bachelor thesis was to verify geographical autenticity of Moravian white wines based on elemental analysis. This data were completed with the analysis of organic acids, fenolic compounds and atioxidants in wines. There were used two spektrometric methods for the elemental analysis (ICP-MS and ICP-OES). The concentration of organic acids was mesured by Ion chromatography. To determine the concentration of phenolic compounds in wines there was used the high performance liquid chromatography (HPLC-DAD), the content of antioxidants and the total content of phenols was measured on spectrophotometer. In total there were 33 samples of wine from 4 Moravian subregions. For the purpose of determination the samples in groups the dataset was firstly corrected by Grubbs test for remote results. From those data the box plots were created which represents the minimal, maximal and mean concentrations of each measured component. Furthermore the analysis of variance was applied, which picked up 12 statisticly valuable parameters from the whole 47. By appliyng the multidimensional statistical methods (Pearson correlation analysis (PCA) and discriminant analysis (DA)) were compiled mathematical models for the division of Moravian wines according to geographical origin. The success rate of the discrimination test was 96,97%. The cross-validation test showed an 81,82% success rate for classifying unknown samples.
Monitoring of chemical composition changes in wine during the wine making process
Orságová, Marie ; Punčochářová, Lenka (referee) ; Diviš, Pavel (advisor)
The Chardonnay wine variety was harvested in the region of Znojmo on the wine rout Načeratický kopec. In connection with the entire winemaking process of this particular variety, research was focused on mineral concentration changes during the maturation process. The theoretical part characterizes the technology of wine production, as well as the classification and chemical composition of wine. In the experimental part, the analytical technique of inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the determination of minerals (K, Ca, P, Mg, Na, Zn, Cu, Fe and Mn) in wine. The data show the differences in the concentrations of all macroelements and microelements during the whole wine production technology.
Characteristics of Moravian wines of the Pálava variety
Horáková, Lenka ; Divišová, Radka (referee) ; Diviš, Pavel (advisor)
This bachelor thesis deals with the chemical characterization of Palava wines from the Moravian region and the possibility of using chemical analysis of wines to verify the geographical origin of the Palava variety. The theoretical part of the bachelor thesis describes the wine-growing areas in the Czech Republic and the origin of the Palava variety. The theoretical part discusses the chemical composition of wine and the issue of wine adulteration and methods used to check the authenticity of wines. The experimental part of the bachelor thesis is focused on elementary analyses, analyses of selected phenolic compounds, organic acids, total phenolic compounds and antioxidant activity of wines. The measured data were evaluated using statistical analysis techniques. Analysis of variance, principal component analysis and discriminant analysis were used. The results of this work showed that with the help of chemical analyzes and statistical techniques it was not possible to distinguish samples of Pálava wines according to individual Moravian subregions. However, this study proved that the wines of the Pálava variety have a characteristic chemical composition and it can be distinguished on the basis of chemical analysis from other white wines from the wine-growing region of Moravia.

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2 Diviš, Patrick
3 Diviš, Petr
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