National Repository of Grey Literature 199 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Analyses of inverted repeats localization in bacterial genomes
Šedý, Michal ; Zemanová, Jana (referee) ; Brázda, Václav (advisor)
Inverted repeats (IR) are common part of DNA of all living prokaryotic and eukaryotic organisms. Inverted repeats plays an important role in the regulation of basics cells processes. They are responsible for formation of cruciform structures. Inverted repeats also cause genomic instability and can be a source of numerous mutations. Cruciform structures can be recognized by DNA-binding proteins and can also act as a transcriptional regulators. Using the Palindrome Analyser tool, the frequency of IR and localization of inverted repeats in bacterial genomes was analyzed. The frequency of IR across the bacterial genome is variable. The frequency of short inverted repeats shows an approximately quadratic dependence on the %GC content in the genome with a minimum of about 50% of GC content. The localization of inverted repeats with respect to “annotated features” show a non-random distribution. The frequency of IR for most features is higher “outside” than “inside”.
Production and characterization of cheese with the addition of plant extract
Kučerka, Štefan ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This master´s thesis deals with production and characterization of fresh cheese with addition of herb extracts, specifically extracts from Plectranthus amboinicus and Echinacea purpurea. The purpose of this thesis was to prepare samples with higher sensory quality and nutritional value. Produced cheeses were characterized in terms of volatile (aroma) substances, fatty acid content, total phenolic substances, antioxidant activity and sensory quality. Cheese sample with added extract from E. purpurea reached the highest value of total phenolic compounds (0,172 ± 0,019 mgGAEg-1 of cheese) and antioxidant activity (91,2 ± 2,2 gTEACg-1 of cheese). Cheese sample with added extract from P. amboinicus, compared to standard cheese sample (without added extract) also reached higher values of total phenolic compounds and antioxidant activity. 43 volatile (aroma) compounds were identified in both samples with added extracts (P. amboinicus, E. purpurea), in standard cheese sample it was 33. In sample with E. purpurea camphor was present in high amount (15,23 %) responsible for the camphor aroma, camphor was also identified in small amount in sample with P. amboinicus. Highest volatile matter content was identified in sample with P. amboinicus. Standard cheese sample was rated as the best from the sensory perspective. Addition of extracts had negative effect on color, taste, and aroma perception of cheese. Strongest herbal taste was identified in sample with E. purpurea, brownish color of this sample manifested in lower pleasantness of color. Obtained results show, that extract addition increases the nutritional value of cheese (higher content of aromatic substances and phenolic compounds, higher antioxidant activity), but lowers sensory quality and overall consumer acceptability.
Use of insect flour for food and feed purposes
Árendásová, Veronika ; Zemanová, Jana (referee) ; Němcová, Andrea (advisor)
Insect meal has excellent potential as food or feed. There is a need to provide enough food for the growing population, which is linked to the increasing demand for livestock production. Meat and fish have always been the staple of the human diet as a rich source of proteins and fats for human nutrition. Fish is a good source of animal protein and fat for humans, which forms the basis of the diet of a large number of people who generally live in coastal areas. The increasing demand for fish is associated with a growing interest in high-quality and affordable fish feed. Nowadays, the main ingredient in fish feed is fishmeal, and the price is constantly increasing. The sustainability of the aquaculture industry depends on finding a substitute for fishmeal with the same nutritional value and availability. Recently, there has been a growing interest in animal protein from insects for fish fattening. This thesis focused on analysing insect meal from mealworm larvae (Tenebrio molitor) and its use for food and feed purposes. The theoretical part describes the mealworm, the use of insect meal for human nutrition, and fish fattening. It also describes the requirements of fish for individual nutrients and the characterisation of insects for feeding purposes, focusing on the mealworm used as an alternative feed ingredient in fish. The individual major nutrients, namely protein, lipids, fatty acids, amino acids, fibre, chitin, and selected minerals, were determined in the experimental part. The experimental part was divided into two parts, and the first part was divided into two phases. The first phase was used to determine the nutritional components in two fractions of insect meal from Tenebrio molitor larvae. The first fraction contained the fine fraction, and the second fraction the coarse fraction of insect meal. In the second phase, the content of nutritionally significant components was only determined in the insect meal from dried larvae without fractionation. A fish feed was designed from the analyses results. In the second part, the effect of the addition of insect meal from Tenebrio molitor for food purposes was investigated; specifically, the sensory properties of muffins were monitored. From the results, it can be observed that the nutritional composition of the insect meal suggests the possibility of using the mealworm larvae as an ingredient in the fish diet. The insect meal contains a high proportion of valuable proteins and lipids necessary for fish farming and a low proportion of carbohydrates, which unlike humans, fish do not need in their diet. The sensory analysis results indicate that consumers are not prepared to eat foods with added insects.
Production and characterization of cheese analogues with the addition of vegetable oil
Babištová, Lucie ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This thesis deals with the production and characterization of cheese analogues, ie products in which some of the dairy components are mutually or completely replaced by a non-dairy component. Model samples of fresh cheese and analogues of fresh cheese (standard) with the addition of linseed and rapeseed oil were produced by a standard technological procedure in MENDELU Brno. The content of bound and free fatty acids, volatile (aroma) substances and sensory quality was monitored in the samples. The main focus was to evaluate the effect of added vegetable oil on the monitored parameters. The fats from the sample were extracted with a mixture of diethyl ether and petroleum ether. Fatty acids were converted to methyl esters by boron trifluoride-catalyzed acid esterification and subsequently identified by GC-FID. The analysis found a higher content of fatty acids in cheese analogues in comparison with the control sample, also the content of unsaturated fatty acids increased. The HS-SPME-GC-MS method was used for the identification and semi-quantification of volatile substances (aromatic substances). 56 volatile compounds were identified in the samples; The percentage of individual chemical groups differed significantly, the highest content was found in the control sample. Sensory evaluation was performed using a scale and a serial test. In all of monitored indicators (apparence, color, consistency, smell and taste) the control sample was evaluated as best. As for the analogues the taste and smell of used oils were detected, which was unpleasant for the evaluators. The obtained results show that the addition of vegetable oils increases the nutritional value of cheeses (higher content of unsaturated fatty acids), but reduces their sensory quality and overall consumer acceptability.
Production and evaluation of fermented dairy products
Jasimová, Zahraa ; Vítová, Eva (referee) ; Zemanová, Jana (advisor)
This bachelor thesis deals with the production of fermented dairy products and their sensory evaluation. As a model sample a kefir, more precisely, kefir milk, was chosen, which is a product made by using a combination of lactic acid bacteria and yeast (so-called kefir culture). In the theoretical part, milk cultures used for production of fermented products; as well as technology of individual fermented dairy products are characterized. Furthermore, their requirements for sensory quality and the specifics of sensory evaluation are described. In the experimental part, two suitable methods of sensory analysis were selected to compare three samples, two of them were commercial and served as a comparative samples and one was a manufactured sample. The task of the evaluators was to evaluate the color, appearance, taste, smell, consistency and overall acceptability of individual samples using a five-point scale. The model sample of a kefir milk manufactured in laboratory, was evaluated as the worst (least sensory acceptable) mainly due to the lumpy consistency, the taste and the smell reminded to some evaluators sheep's milk.
Biologically active substances of the Gotu kola plant
Šumberová, Michaela ; Nábělek, Jakub (referee) ; Zemanová, Jana (advisor)
The Bachelor thesis focuses on the preparation and characterization of the extract of Gotu kola (Centella asiatica). The theoretical part summarizes commonly analyzed groups of biologically active compounds of herbs and introduces potential applications of the extract in food industry. Moreover, an overview of possibly used extraction methods and analytical methods for the evaluation of biologically active compounds of the extract are presented. As for the experiment, the extract of the fresh Centella asiatica herb was prepared by maceration in ethanol and then analyzed by three chosen methods. The total phenolic content of the extract analyzed by the Folin-Ciocalteu test was 0.74 ± 0.08 mgGAE·g-1. As for the quantification of antioxidant activity, the TEAC test was performed and the antioxidant activity of the extract was 289 ± 81 µg·ml-1. The volatiles present in the extract were identified by gas-chromatography mass-spectrometry in combination with solid-phase micro-extraction. Sesquiterpenoid hydrocarbons were the most dominant group of the extract, in which -farnesene (33.28 %), -caryophyllene (25.01 %), and -humulene (20.91 %) were the major compounds.
Study of selected vegetable oils from nuts
Lovásová, Kristína ; Kovalčík, Adriána (referee) ; Zemanová, Jana (advisor)
The bachelor´s thesis deals with the characterization of the selected nut oils. The theoretical part concentrates on the topic of vegetable oils, their composition and properties. It also focuses on the nuts, the specification of the selected nut oils and their use in different industries. It includes an overview of analytical methods suitable for assessing the quality of oils. The experimental part compares the results of the oil characterization using the selected methods. Based on the results, the differences between the samples were evaluated. The properties of the oils were determined on the basis of fat characteristics. These were subsequently specified by the determination of fatty acid composition. Fatty acids were determined using gas chromatography with a flame-ionization detector after conversion to methyl esters by acid esterification with boron trifluoride. The determination of volatile compounds was performed through solid-phase microextraction with gas chromatography separation and mass spectrometry detection. According to the fat characteristics, in particular the peroxide value, it was found that both oils were partially oxidatively degraded, even though they were stored in the refrigerator (4 °C). A total of 13 saturated, 7 monounsaturated and 4 polyunsaturated fatty acids were detected. The total content of fatty acids varied, the higher content was detected in the walnut oil. Significant differences occurred in the composition of unsaturated fatty acids; the hazelnut oil had a higher content of monounsaturated oleic acid, the walnut oil had a high content of polyunsaturated linoleic and -linolenic acids. A total of 29 volatile compounds were identified, the number and content of volatile compounds in samples differed. 20 volatile compounds were identified in the walnut oil, and 19 compounds in the hazelnut oil. The higher content was in the hazelnut oil, the quantitatively most important group were aldehydes in both oils.
Antimicrobial activity of selected natural extracts
Šandová, Lucie ; Veselá, Mária (referee) ; Zemanová, Jana (advisor)
The aim of the bachelor thesis was to determine antimicrobial activity of selected natural extracts, specifically three model extracts made from purple coneflower (Echinacea purpurea) and four commercial extracts – true lavender (Lavandula angustifolia), lemon balm (Melissa oficinalis), echinacea herbal drops (Echinacea purpurea) and echinacea extract (Echinacea purpurea) with ginger, against selected microorganisms. Theoretical part is focused on description of bioactive substances that are found in plants. It also describes extraction methods used for obtaining extracts from plant materials, methods for determining antimicrobial activity and then the use of natural extracts in food and cosmetic industry. In experimental part, antimicrobial effect of the extracts was tested against gram-negative bacteria Escherichia coli, gram-positive bacteria Bacillus cereus and yeast Candida glabrata. For determination of the antimicrobial activity, two methods (hole method and disc diffusion method) were used and compared. The highest antimicrobial activity against selected microorganisms was showed by commercial extract of lemon balm, which contains lot of geraniol and citroneloll. Significant antimicrobial activity had also been shown by commercial extract of true lavender. On the contrary, extracts from Echinacea had not shown any antimicrobial activity against selected microorganisms.
Modern vegetable oils useful in food and cosmetics
Plachtová, Kateřina ; Mravcová, Ludmila (referee) ; Zemanová, Jana (advisor)
The aim of this Bachelor’s thesis was to make a literary research of currently most used vegetable oils in food technology, cosmetics and pharmaceuticals focusing on health benefits, possibilities of use. Two selected modern vegetable oils were specified that are currently a subject of research in respektive fields. The selected modern oils were carrot seed oil and raspberry seed oil. A literary recherche was drawn up dealing with these oils from the perspective of their composition, charakteristics, properties and use in food technology, cosmetics and pharmaceuticals. In the experimental part of the thesis the fatty characteristics of carrot seed oil and raspberry seed oil were determined: acid value, saponification value, ester number, iodine value, peroxide value. Also fatty acids present in the oils were identified and quantified using gas chromatography with flame ionization detector. Fatty acids were analysed as their methylesters. Derivatization was was performer by alkalic esterification using methanolic solution of potassium hydroxide. In conclusion, selected oils were compared in terms of fatty characteristics and fatty acid profiles. Fatty acid composition was also compared to fatty acid composition found in literature sources.
Influence of early and late drought on grain proteins content and composition in early and late variety of wheat
Vojteková, Vanesa ; Zemanová, Jana (referee) ; Hrstka, Miroslav (advisor)
In this bachelor thesis, the influence of early and late drought on grain protein content and composition in an early and late variety of winter wheat was studied. The varieties used were Avenue and Tobacco.One part of the plants was cultured under the conditions of early drought (bloom season), another part was grown under the conditions of late drought (grain filling season), the last part was grown under the conditions of natural irrigation. Half of the plants were fertilized using nitrogen fertilizer (200 kg N/ha), the second half of plants were without nitrogen fertilizer (0 kg N/ha). Wet gluten, crude protein content, gliadin and glutenin content were determined from flour samples. Results were evaluated by analysis of variance. Drought resistance depends on the genotype. Tobak genotype is more tolerant to climatic conditions, but the drought had a more significant effect on gliadin and glutenin ratio than on the Avenue genotype. Late drought increased wet gluten content in both genotypes and both types of fertilization. On the other hand, the early drought did not affect wet gluten content. Early drought decreased gliadin content, with the exception of Avenue genotype without fertilization. Early drought also increased glutenin content. Late drought increased glutenin content only in the unfertilized variant. Early drought increased glutenin content which leads to decreased gliadin content, especially for nitrogen fertilization. Late drought caused a decrease of gliadin and glutenin ratio, except for Tobak genotype with fertilization. Late drought increased crude protein content, except for Tobak genotype without fertilization. Early drought decreased crude protein content, especially for the unfertilized variant.

National Repository of Grey Literature : 199 records found   1 - 10nextend  jump to record:
See also: similar author names
14 ZEMANOVÁ, Jana
2 ZEMANOVÁ, Jitka
2 ZEMANOVÁ, Jiřina
1 Zemanová, Jana Bc.
2 Zemanová, Jiřina
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