čas: 23.4.2021 01:45:46
Obnovit | RAW
Department of Food Analysis and Nutrition
List of available PhD theses
Biologically active compounds in Cannabis sativa and other natural resources
The doctoral thesis will focus on the effective isolation, purification, and analytical characterization of biologically active secondary metabolites, including minor ones, contained in Cannabis sativa plants and other plant sources using modern instrumental technologies. Within the interdisciplinary cooperation, biological activity will also be evaluated. The acquired knowledge will be reflected in the design of new products such as cosmetics or food supplements.
Biologically active compounds of plants and their changes during processing and storage
Plant biologically active compounds can have positive as well as negative effects on the human body. Levels of plant secondary metabolites depend on the type of plant or the growing conditions, but are also affected by processing and storage conditions Modern analytical methods, based mainly on the technique of ultra-performance liquid chromatography coupled with high resolution mass spectrometry detection, are applied for monitoring these compound levels and the assessment of individual compounds stability. For the assessment of the authenticity of vegetable raw materials, metabolomic fingerprinting / profiling technique with application of sophisticated statistical methods for the evaluation of obtained data is applied.
Critical assessment of potential of various gas chromatography - mass spectrometry platforms in food analysis
The doctoral thesis will focus on a critical assessment of performance characteristics of analytical methods employing various set-ups of gas chromatographic (GC) separation systems and various types of mass spectrometric analyzers. For separation of complex mixtures, the use of two-dimensional gas chromatography (GCxGC) will be tested, for detection, tandem time-of-flight (Q-TOF) high resolution and/or triple quadrupole (QqQ) mass analysers will be employed. The applications will be concerned with food quality, safety and authenticity evaluation. Special attention will be paid to approaches based on non-target screening (fingerprinting / profiling).
Development of analytical procedures for the determination of new per- and polyfluoroalkylated substances in foods and biological samples
This dissertation will be focused on the development of ultra-sensitive analytical methods for the determination of a wide range of per- and polyfluoroalkylated substances (PFASs) in foods, especially of animal origin, and in drinking water, which are the main dietary source of human exposure. The work will be firstly aimed on the extension of existing methods by new substances, e.g. short-chain carboxylic acids (C2-C3), telomeric compounds including their precursors. Liquid chromatography coupled with tandem mass spectrometry will be used for the analysis of targeted chemicals, based on their polarity and volatility, for some substances gas chromatography with mass spectrometry will also be applied, to achieve required performance characteristics. Subsequently, the new analytical procedures will be applied to assess the exposure of the population of the Czech Republic to these substances on the basis of their analysis in selected food commodities and drinking water. The dissertation will also include a study in the field of human biological monitoring, where the targeted PFASs will also be determined in human biological samples such as breast milk, blood serum and urine. Distribution of these substances in individual types of samples will be evaluated. This work will provide new data necessary for the complex risk assessment associated with the exposure of different population groups to these substances
Development of analytical procedures for the determination of new perfluoroalkylated substances in food and biological samples
This dissertation will be focused on the development of ultra-sensitive analytical methods for the determination of a wide range of perfluoroalkylated compounds (PFAS) in foods, especially of animal origin, and in drinking water, which are the main dietary source of human exposure. The work will be firstly aimed on the extension of existing methods by new substances, e.g. short-chain carboxylic acids (C2-C3), telomeric compounds including their precursors. Liquid chromatography coupled with tandem mass spectrometry will be used for the analysis of targeted chemicals, based on their polarity and volatility, for some substances gas chromatography with mass spectrometry will also be applied, to achieve required performance characteristics. The new analytical procedures will subsequently be applied to assess the exposure of the population of the Czech Republic to these substances on the basis of their analysis in selected food commodities and drinking water. The dissertation will also include a study in the field of human biological monitoring, where the targeted PFAS will also be determined in human biological samples such as breast milk, blood serum and urine. It will be evaluated for the distribution of these substances in individual types of samples. This work will provide new data necessary for the complex risk assessment associated with the exposure of different population groups to these substances.
Evaluation of food safety from the point of view of newly occurring groups of mycotoxins
Mycotoxins are toxic secondary metabolites of microscopic filamentous fungi occurring naturally on agricultural plants / crops. Today, hundreds of these substances are known, and their structure and biological effects differ depending on the type of their producer, the type of colonized plant, and environmental conditions. As chemically and thermally stable substances, they are being transferred into food and feed to a relatively large extent and can pose a health risk for consumers. Nowadays, the health risks of only a small fraction of these substances have been assessed, so data on the occurrence of new groups of mycotoxins, occurrence of which is related to ongoing climate change, are highly desirable and necessary for the risk assessment. The topic of the dissertation thesis reflects the need to obtain new information on the occurrence of mycotoxins (specified also by the European Food Safety Authority), and will include the development of new modern analytical methods based on liquid chromatography and mass spectrometry, and their implementation in screening and quantification of a wide range of mycotoxins in food and feed.
Evaluation of vitamins' levels in human biological samples
In this dissertation, analytical methods for the determination of lipophilic vitamins (A, D, E) and vitamin C in human biological samples such as breast milk and blood serum will be will be developed. The methods will be used to evaluate the levels of vitamins in breast milk. These vitamins are important for lung development and for brain development. According to published data, concentration of these vitaminas may be insufficiently in breast milk and it is often difficult to supplement the required vitamins in oral form in premature newborns. Therefore, in the next phase, substitution will be tested by oral intake to the mother and subsequent production into milk. The study will be carried out in cooperation with the hospital in České Budějovice. The project will monitor the concentration of vitamins A, D, E, C, omega 3 and omega 6 fatty acids in the mother's blood, milk and newborn's blood. Distribution of substances among these biological fluids will be evaluated. The study will provide very important data in the field of nutrition of premature babies.
Innovative strategies for food fraud detection
The doctoral thesis realized within the international project will focus on the use of modern instrumental methods, especially high-resolution mass spectrometry, for the analysis of food raw materials, foods and food supplements. To recognize a fraud / verify authenticity of investigated samples, a strategy of comparing measured ‘fingerprints´ and profiles of selected biomarkers with records in a database constructed on the basis of fully characterized, authentic samples, will be employed. Advanced multi-dimensional chemometric strategies will be used for data processing. The project will also assess the potential health risks to consumers related to fraud.
Investigation of the stability and changes of food products using direct spectral methods
The dissertation is focused on the application of selected direct spectral methods such as infrared spectrometry (ATR-FTIR) or mass spectrometry (DART-MS) in order to investigate the stability and changes of food products during storage and conventional culinary treatments. The aim of this work is to develop analytical procedures suitable for their characterization for various materials with a focus on key components such as lipids or carbohydrates so that they can be used to authenticate or differentiate them according to the origin or degree of technological processing.In addition to the applied analytical methods, advanced statistical methods, including multivariate data analysis, will be used for data processing, which allows sorting into characteristic groups.
Metabolomics as a tool illustrating the interactions between a plant and its microbiome
Microbial consortia present on agricultural plants have a major impact on their prosperity (growth, resistance to pathogens, yields, chemical composition, etc.). An important role is played by the microbial species inhabiting the plant itself (bacteria, micromycetes, yeast), as well as the relationship between the microorganism and the plant (endophyte vs. pathogen). The topic of the dissertation will include the characterization of (bio)chemical changes taking place in the system of plants and microorganisms using metabolomics, as a complex analysis of endogenous and exogenous metabolites with low molecular weight up to about 1500 Da. Attention will be focused on Vitis vinifera L. (vine) and Hordeum vulgare L. (sown barley), as one of the most important agricultural plants grown in the Czech Republic.
Monitoring of the assessors sensitivity to selected tastes
Taste is a sensory modality that leads organisms to identify and consume nutrients and avoid toxins and indigestible materials. How taste (taste perception) works has not yet been fully explored, because the perception of the taste of food and drink results from complex interactions between individual sensory systems. In addition to the hitherto recognized basic tastes, a fatty taste which lies at the interface between somatosensory and taste perception can also be detected by means of dedicated receptors through taste cups. For many years, the recognition of fat in food has been considered primarily a function of its structure, and thus of somatosensory origin. Because specific membrane receptors have been described on taste bud cells for the detection of free fatty acids, a fatty taste is likely to be considered another basic taste. The work will be realized mainly in the sensory laboratory, which is equipped according to the relevant international standard ISO 8589. Part of the work will be monitoring the sensitivity of the assessors to selected tastes. Attention will be paid especially to the fatty taste and the effect of fatty acids on the taste perception, the sensitivity of the assessors to the metallic taste of zinc salts and substances that mask individual tastes.
Nutraceuticals and foods that reduce oxidative and carbonyl stress
The subject are components of food and nutraceuticals that are able to reduce the redox potential and the amount of reactive carbonyl compounds formed as products of sugars transformation. The active components can act as reducing agents (or different antioxidants) and reagents able to scavenge reactive carbonyl species (RCS) in both food and in vivo. RCS are formed during non-enzymatic browning reactions in food (Maillard reaction) and in vivo (glycation) as well as due to lipid oxidation. The goal is finding foods and nutraceuticals that may significantly suppress the above-mentioned kinds of stress promotors and identifying active compounds, which are behind these effects.
Physiologically beneficial substances formed de novo during food processing
The subject are physiologically desirable substances formed by complex non-enzymatic browning reactions during food processing. The research is focused on the products contributing to increased redox stability and decreased levels of oxidative stress-inducing carbonyl compounds, in both food and human body. The goal is finding the optimum conditions for the formation of these protective substances in processed foods and designing a procedure for the production of functional foods by the addition of suitable precursors before processing.
Reactivity of chloropropanediol and glycidol esters in foods
The discovery of ester-bound 3-chloropropane-1,2-diol (3-MCPD), 2-chloropropane-1,3-diol (2-MCPD) and glycidol in refined edible oils and other foods has initiated their monitoring in many European Union countries. The work will be focused on the study of yet insufficiently investigated reaction mechanisms leading to the formation and degradation of these compounds. Study will take place in model systems as well as in food. Knowledge of mechanisms, products and reaction kinetics of formation and decomposition under various conditions (water activity, pH, temperature) can help to predict concentrations of these process contaminants in real matrices and help to find suitable detoxification processes.
Study of plastic additives used in agriculture
This dissertation will be implemented within the EU project PAPILLONS - Plastic in Agricultural Production: Impacts, Lifecycles and LONg-term Sustainability. Plastics are a very important commodity in agriculture that improves crop protection and yield. In Europe, between 3 and 4 million tons of agricultural plastics are currently used, which generates 1 million tons of waste. During use and at the end of their life, some plastics degrade and form fragments, including micro- and nanoplastics, which may temporarily or permanently accumulate in the soil, which can then be transferred to agricultural crops and some animals. These plastics contain various additives, such as substances used as antioxidants, antistatics, flame retardants, plasticizers, pigments, heat stabilizers and UV stabilizers. This work will focus on the development of analytical methods for the determination of various plastic additives in fragments of plastics, agricultural plants and selected animals. The methods will be used to analyze samples taken in different regions of the EU, thus obtaining data for a comprehensive assessment of the risks associated with the use of these plastics in agriculture.