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Analysis of selected biologically active substances in cereal products
Skutek, Miroslav ; Kočí, Radka (referee) ; Márová, Ivana (advisor)
Presented diploma thesis was focused on study of biologically active compounds, especially some sugars in cereal products. In experimental part the total of 29 different cereal materials, food industry waste products and natural complex matrixes (microbial polysaccharide, honey, beer) were used. As a part of this work optimization of analytical methods suitable for analysis of simple sugars, oligo- and polysaccharides was done. In cereal samples reduced and neutral sugars were analyzed spectrophotometrically and individual sugars were detected by chromatography. For HPLC/RI analysis optimal mobile phase composition and chromatography conditions were proposed. For mono- a oligosaccharides C18-NH2 sorbent, mixture acetonitril:water 75:25 as mobile phase and flow 1 ml/min were verified as suitable separation parameters. Thin layer chromatography of mono- and oligosaccharides was optimized too. Introduced chromatography and spectrophotometry methods were then applied to analysis of cereal samples. As a model sugar natural microbial polysaccharide pullulan was used to analytical method testing. In cereal products and food matrixes total neutral and reduced sugars as well as products of their acid and enzyme hydrolysis were measured. Detailed analysis of some glycoside composition was tested too. As the most usable method for both qualitative and quantitative analysis of cereal sugars HPLC/RI method was found. To detailed identification of malto-oligosacharides tandem LC/MS/MS technique using derivatization by 1-phenyl-3-methyl-5-pyrazolon was tested too.
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Application of capillary electrophoresis in analysis of saccharide component of glycopeptides
Šimonová, Alice ; Křížek, Tomáš (advisor) ; Kubíčková, Anna (referee)
The aim of this thesis was the development of the method for the determination of eight monosaccharides commonly found in glycoproteins by capillary electrophoresis. Namely, it was determination of glucose, galactose mannose, N-acetylglucosamine, N-acetylgalactosamine, fucose, N-acetylneuraminic acid and xylose. Total length of silica capillary with inner diameter of 10 m was 50.0 cm and effective length was 35.0 cm. Background electrolyte was compound of sodium hydroxide of 50 mmol/l concentration, disodium phosphate of 22.5 mmol/l concentration and cetyltrimethylamoniumbromide of 0.2 mmol/l concentration. Samples were injected hydrodynamically with pressure of 5 kPa for 70 s, driving voltage was -30 kV and the pressure of 270 kPa was applied to the outlet vial during the separation; capacitively coupled contactless conductivity detector was used to detect the analytes. The limits of detection were between 5 and 7 mg/l and the limits of quantification were between 16 and 22 mg/l. Repeatability of peak areas and migration times related to 4-(2-hydroxyethyl)-1-piperazinethanesulfonic acid as an internal standard showed values of relative standard deviation lower than 4 %. Conditions for hydrolysis of oligosaccharides to monosaccharides were determined as 4M hydrochloric acid and 100 řC, hydrolysis...
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The effect of water stress on the content of monosaccharides in potato tubers
Podhorecká, Klára ; Orsák, Matyáš (advisor) ; Hnilička, František (referee)
Bachelor thesis is focused on monitoring of influence on selected metabolites, especially monosaccharides. The first part is devoted to short characterization of potatoes, therefore the importance of this crop, morphology, cultivation and also are described demands of potatoes on environment and nutrition.
In the next section is detailed discussed problems of the chemical composition of tubers with a focusing on carbohydrates. Potatoes are globally consumed and are popular source of carbohydrates. Potatoes are rich in vitamins also, especially in vitamin C, B3 and B6. Potatoes contain a high content of minerals, especially potassium and magnesium, too. As another substances are in potatoes colorants, antioxidants, phenolic and related substances, proteins, and small amount of lipids. It is noted that proteins of the potato tuber are ranked among nutritionally valuable proteins of vegetable origin. Among this proteins is ranked Patatin, which is considered to be a major reserve protein and it is placed in the vacuoles. Substances, which has a negative effect on the human body are called Glycoalkaloids the opposite. Glykoalkaloids are synthesized by plants of the family Solanaceae. The most significant substances in potatoes are alfa-solanine and alfa-chaconine. Value of tubers is primarily determined by their chemical composition, which forms food and raw materials. The contents of sugars in the tubers are relatively low (0,5 % of the original mass), and even though their contents are important both in aspect of manufacturing and in sensory aspect. The main reducing monosaccharides are ranked glucose and fructose, typically with a concentration of 0,15 - 1,5 %. The sugar content significantly affects internal and external quality characteristics especially fried products. Several studies confirm that the accumulation of carbohydrates might help resist extreme stress conditions, especially low temperatures, salinity and water deficiency.
In the next chapter is created summary of stress conditions effects on plants with focusing on potatoes. In plants we can talk about stress, if variability of negative environmental factors exceeds a certain limit. The main theme and also the most limiting factor is deficiency of water in other words water stress. Also were mentioned other factors abiotic and biotic factors marginally.
By effects of stress reaction is created a specific level of adaptive skills. Temporarily it can lead to acclimatization, which increasing the resistance to abiotic stressors. Most of plants are trying to establish the tolerance to stress. In this Chapter were also described changes during storage and during heat treatments of potato, which leads to an undesirable darkening of the tubers. Excessive levels of reducing sugars cause unacceptable browning of fried products.
In the last chapter is described selected methods of determining carbohydrates. These methods are based on reducing properties of sugars, on their condensing reactions by color, measurement of optical activity, measurement of refractive index, separation methods and others.
The methodic of work clarifies the determination of reducing monosaccharides (glucose, fructose), sucrose by the high performance liquid chromatography (HPLC) in four selected varieties of potatoes from harvest of 2015.
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Analysis of selected biologically active substances in cereal products
Skutek, Miroslav ; Kočí, Radka (referee) ; Márová, Ivana (advisor)
Presented diploma thesis was focused on study of biologically active compounds, especially some sugars in cereal products. In experimental part the total of 29 different cereal materials, food industry waste products and natural complex matrixes (microbial polysaccharide, honey, beer) were used. As a part of this work optimization of analytical methods suitable for analysis of simple sugars, oligo- and polysaccharides was done. In cereal samples reduced and neutral sugars were analyzed spectrophotometrically and individual sugars were detected by chromatography. For HPLC/RI analysis optimal mobile phase composition and chromatography conditions were proposed. For mono- a oligosaccharides C18-NH2 sorbent, mixture acetonitril:water 75:25 as mobile phase and flow 1 ml/min were verified as suitable separation parameters. Thin layer chromatography of mono- and oligosaccharides was optimized too. Introduced chromatography and spectrophotometry methods were then applied to analysis of cereal samples. As a model sugar natural microbial polysaccharide pullulan was used to analytical method testing. In cereal products and food matrixes total neutral and reduced sugars as well as products of their acid and enzyme hydrolysis were measured. Detailed analysis of some glycoside composition was tested too. As the most usable method for both qualitative and quantitative analysis of cereal sugars HPLC/RI method was found. To detailed identification of malto-oligosacharides tandem LC/MS/MS technique using derivatization by 1-phenyl-3-methyl-5-pyrazolon was tested too.
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Validace nutričních parametrů uvedených na obalech vybraných potravin
Pláteníková, Markéta
The main purpose of this diploma thesis was to study legislative requirements about marking food products with nutrition labels and summarize the activities and procedures of supervising organizations connected to problematic of goods marking. One of the goals was to briefly describe technological and producing methods of selected food - ham, cheese, kephir milk, baby food with fruit, wafer, bread, wholemeal puffed bread and chocolate. Next goal was to evaluate the risks of food consumption with deceptive nutrition labels. In the practical part of this thesis I have determined quantity of saccharides, lipids, proteins and salt in selected food products by standard methods. Simple saccharides were determined by Schoorl's method and starch volume by Ewers's method. Lipids were determined by Soxhlet's extraction and after put through derivatization. In gas chromatograph (GC) were detected fatty acids. Apart from the Soxhlet's extraction was made also extraction according to Hara and Radin (1987) for comparison. Proteins were determined by method using nitrogen according to Kjehdal with adjustments according to Winkler. The amount of salt was detected analytically by argetometric precipitating titration. Determination the volume of nutritive parameters was made in three ranks of selected products. From obtained results were evaluated possible risks, which might be caused by consumption of food products with deceptively stated nutritive labels.
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