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Representation of biologically active substances in the grape seeds (Vitis vinifera L.)
Horníčková, Štěpánka ; Hejtmánková, Alena (advisor) ; Vlastimil, Vlastimil (referee)
Seeds of 41 white and 22 blue vine varieties cultivated on six vine-growing areas were assessed as a by-product after winemaking on the contents of total polyphenols (TP) and phosphorus (P) spectrophotometrically, total tocols (TC) including individual tocols by HPLC-FLD, and metals (Ca, Mg, Na, K, Fe, Zn, Cu, and Mn) by FAAS. Remaining TP and TC levels were mainly affected by the variety, while levels of microelements (Cu, Mn, and Zn) and P or K by the vine-growing area. The highest TC and TP levels were found in the seeds of white varieties. Varieties of grape seeds have significant impact on the gamma-tocotrienol content. The color of grape varieties has significant impact on alpha-tocotrienol content. Grape seeds from grape cultivated on the Czech growing area contained higher levels of macroelements except P, however no significant differences between growing areas have been found. The crop year has significant influence on TP, Fe and Cu content. Results herein revealed the considerable potential of grape seeds, a by-product of the vinification process, as a valuable inexpensive source of high added value of nutritionally beneficial compounds - polyphenol and tocol antioxidants and macro- and microelements for use as feed additives in animal nutrition.
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Determination of different forms of casein in milk
Kaňková, Veronika ; Hejtmánková, Alena (advisor) ; Markéta, Markéta (referee)
Casein proteins are important escpecially for cheese making. In addition to technology and other factors, casein concentration in milk and relative representation of individual casein fractions influence cheese yield. Majority fractions are alfa-casein, beta-casein and kappa-casein. For the determination of proteins in the milk can be used electrophoretic techniques or near infra-red spektrometry. High performance liquid chromatography (HPLC) is going to be used. HPLC is widely used analytical method, which is based on differential affinity of the substances to the mobile and the stationary phase.
The thesis has introduced the method of determining the casein fractions by HPLC. The method was partially optimized using cow milk and calibrated to the standard solutions, which were purchased casein fractions derived from the bovine milk. Real samples of cow, sheep and goat milk were analyzed. The goat milk was available in several variants: Sanski goat milk and white shorthair goat from domestic or farm breeding. All milk samples were analyzed for casein and casein fractions proportions. Chromatograms show that the casein formula is different in cow, sheep and goat milk. Different concentrations of the casein fraction in the milk of various animal species have been statistically detected in almost all cases. The exception was the concentration of beta-casein in the milk of white shorthair goat from the domestic and the farm breeding and cow milk. In these types of milk there was no statistically significant difference in the concentration of beta-casein. Analysis of individual samples of white shorthair goat milk from the farm breeding shown that casein content in the milk of different animals reared under the same conditions may be different. Ratios of beta-casein to alfa-casein, beta-casein to kappa-casein and alfa-casein to kappa-casein were evaluated in all samples. Interspecific comparisons proved that ratios were statistically significantly different in all milks. In the milk of Sanski goat, there was found the stable ratio of beta-casein to alfa-casein during lactation. For all goat milk there were typical higher values of the ratio of beta-casein to kappa-casein. The ratio of alfa-casein to kappa-casein was highest in the sheep milk. Despite some shortcomings, it is possible to use the HPLC method possible for these purposes, but it is necessary to continue with its optimization.
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The importance of legumes in the human diet
Střelková, Tereza ; Hejtmánková, Alena (advisor) ; Martina, Martina (referee)
Legumes are part of human diet since Early Years and they have important role. In Czech Republic the most commonly consumed legumes are beans, peas and lens and in recent years even cicer (commonly chickenpea) and soya. Yearly consumption of legumes in human diet in Czech Republic is about 2,5 kg per person, which is less than in other countries but the consumption is slightly increasing.
Being very good source of protein, legumes as source of non-complete protein should be combined with other sources of protein preferably those based on cereal. Legumes are also source of carbohydrates, from which big part is favourable mix of starch and fiber. Present minerals are e.g. calcium, phosphorus, magnesium, iron and zinc. From vitamins mostly B complex can be found.
Legumes, especially soya, also contain phytoestrogens and other biologically active substances. Phytoestrogens emulate behaviour of human estrogenes and raise interest in areas of research. There are series of scientific foundations for their potential to be used as part of
a treatment for worldwide spread disease like cancer or diabetes, or other common health difficulties e.g. post-menopausal symptoms.
Legumes are often refused in human diet, because of antinutrients they contain. Those are mostly oligosaccharides that are fermented in large intestine which causes flatulence and indigestion. Antinutrients are e.g. enzyme inhibitors or phytic acid.
Antinutrients can be removed by variety of culinary treatments. The easiest are soaking or boiling. The harder, yet very effective treatments, mostly because of time consumptions are e.g. germination or fermentation, or because of technological demands - extrusion. However, heat treatment can degrade proteins and thus lower their usefulness and also reduce biological activity.
Biologically active substances are nowadays intensively researched and studies bring new perspective advantages of consuming legumes.
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The importance of milk and diary products in human nutrition
Maroušková, Nela ; Hejtmánková, Alena (advisor) ; Michlová, Tereza (referee)
Milk and dairy products become integral part of human nutrition and belong to common food. Milk is very valuable because it contains complete proteins. Its disaccharide lactose is a source of energy. Butterfat is easily digestible. Besides potassium, sodium, magnesium, chlorine and sulfur milk contains also dietary elements like calcium and phosphorus.
Milk also contains many trace elements like iron, zinc, iodine, selenium, manganese, fluorine, chromium, cobalt, and molybdenum. Milk is an important source of vitamins. It contains significant amounts of water soluble B and C vitamins alongside fat soluble vitamins E and A and smaller amounts of vitamins K and D.
Milk and dairy products are an important source of calcium. Lack of calcium is the main cause of osteoporosis. Regular consumption of milk and dairy products may reduce the risk of cancer. Nevertheless disproportionate consumption of dairy products containing unsaturated fats can lead to higher incidence of certain types of cancer, higher risk of cardiovascular diseases and metabolic syndrome. Milk contains also compounds that prevent aforementioned diseases.
Milk is the only source of nutrients for newborn children and suckled infants. It is convenient source of nutrients in times of higher nutrient demands especially during pregnancy, nursing and senescence.
Milk, milk cream, fermented milk products, buttermilk, cheese, whey, curd cheese, whey proteins, frozen creams, cream, condensed and powdered milk belong to most important products. Fermented milk products are very beneficial to human health. Those products are sources of complete proteins, calcium, phosphor and vitamins, especially B vitamins. Lactose is decreased making fermented milk suitable for lactose-intolerant subjects. The fermentation process increases the shelf-life of the product while improving the digestibility and microbiological safety.
Milk and dairy products consumption can also have negative impact on human health. Lactase deficiency or lactase insufficient activity in small intestine results in lactose intolerance. Milk can also cause food allergy to the cow's milk.
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The importance of vitamin D and calcium in the human diet
Bártová, Magdaléna ; Hejtmánková, Alena (advisor) ; Michlová, Tereza (referee)
Vitamin D refers to a group of fat soluble steroids. The most important forms are
cholecalciferol occurring in foods of the animal origin and ergocalciferol of the plant origin. Human
accept them in the diet; the fatty fishes, fish liver, and some other foods like milk, eggs or yeasts are
rich resources of vitamin D. Unlike the other vitamins, the synthesis of vitamin D can also take place
in the living body. Cholecalciferol is formed in the skin from its precursor 7 - dehydrocholesterol by
the effect of UVB radiation. The conversion efficiency depends on various factors.
Two successive reaction steps are necessary for the activation of vitamin D. The first step of
hydroxylation occurs in the liver to be formed calcidiol. Calcidiol is the principal form of vitamin D in
the blood acting also as the indicator of body supplies. The second one takes place in the kidneys
where calcidiol is transformed to calcitriol. Calcitriol is assumed as the active hormonal form of
vitamin D binding to the receptor for vitamin D - VDR. The best known and the most explored
function is the effect of vitamin D on the calcium and phosphorus homeostasis. Consequently, vitamin
D also influences the proper functions of muscles and the immune system. It reduces the risk of the
cancer and cardiovascular diseases by various mechanisms as well. However, there are assumed
another effects of vitamin D on the human body, which are not fully yet understood and are the subject
for further research.
Calcium constitutes the major mineral component of bones and teeth. It is an essential nutrient
and therefore it is necessary to supply it with food. Its content in foods is various as well as its
usability from these. The major resources of calcium are milk and dairy products. Calcium is also
present in eggs, mineral waters, certain fishes and food of plant origin. Especially, the plant resources
usability of calcium is limited because of the insolubility of some calcium complexes. Calcium is
essential for the composition structure of bones and teeth. Besides of structural function, it has a main
role in the blood coagulation, neuromuscular transmission or muscle contraction.
Vitamin D has an influence on the usability of calcium because of the efficiency increase of
calcium absorption in the intestine. The lack of both micronutrients leads to skeletal diseases -
osteoporosis, osteomalacia and rickets. The adequate intake of both essential part of food, vitamin D
and calcium, is important especially for the growing children, elderly people, and pregnant and
lactating women.
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The most important dietary sources of lipophilic vitamins
Šafránková, Simona ; Hejtmánková, Alena (advisor) ; Táborský, Jan (referee)
Basic piece of knowledge about nutrition and its need should be integral to every mans general knowledge. One of the vital nutritions ensuring a full-functioning organism are vitamins. Vitamins are essential ingredients, which play an important role in the human body and also in the processes of absorption and the exchange of substances between the external environment and living organism. They were discovered recently during the 20th century. The researches on their effects on the human body are still ongoing.
The vitamins are divided into two basic groups, water soluble vitamins, the so called hydrophilic (vitamins B and C), and fat soluble vitamins, the so called lipophilic (vitamins A, D, E and K).
The vitamin A is important to ensure good vision and recognizing colors. It support the quality and growth of bones, affects the egg and sperm and is needed for proper fetal development.
Vitamin A is found in foods of animal origin, such as dairy products, milk, meat and liver. In the food of plant origin, the vitamin A is replaced with many provitamins, of which most important is the beta carotene. A very rich source of these provitamins are leafy greens such as spinach or cabbage.
The recommended daily intake of vitamin A is 800 microgram, according to the standards of Czech republic. This need depends on the gender and age of each individual. The lack of vitamins A causes photophobia and impaired vision. The excess of vitamin A may be toxic for the organism. The interesting fact is that the beta carotene is not considered to be toxic.
Vitamin A is one of the labile vitamins. It is sensitive to heat, light and oxygen. At a gentle meal preparation and usual diet, the losses are around 20 %.
The vitamin D is consisted of group of several biologically active substances, of which the most important are vitamin D2, ergokalciferol, to be found in foods of plant origin, and vitamin D3, cholekalciferol, to be found in foods of animal origin.
In the human body, vitamin D acts as a hormone, it is formed at one point of the organism, but affects a different part of the body. The vitamin D ensures the intake and absorption of calcium and phosphorus and maintain their balance. It supports the immune system and may help in the psoriasis treatment.
The recommended daily intake of vitamin D is about 2,5 to 10 microgram. Pregnant and lactating women have a greater need for it, as well as infants and children. The lack of vitamin D disturbs the homeostasis of calcium and phosphate metabolism. The excess of vitamin D causes hypercalcaemia.
The most important foods source of vitamin D are liver, oil from fish liver, oil sea fish, fortified margarine and milk.
Vitamin D is sensitive to oxygen and light, its activity is not significantly affected by food storage or preparation.
Vitamin E is a major antioxidant. It is important to maintain the healthy cell wall and skin, muscles, nerves, erythrocytes, heart, and it is also responsible for the proper function of blood circulation.
The recommended daily intake of vitamin E is 8 to 20 mg. Its need is increased during exposure to sunlight and harmful influences, during increased physical exertion and when receiving large amounts of unsaturated fatty acids. The lack of vitamin E almost does not occur in healthy people, since it is present in nearly all basic kind of foods. The hypervitaminosis of vitamin E occurs only rarely, because there is no risk of overdose when receiving a normal diet.
The most important foods source of vitamin E are vegetal oils (such as sunflower and rapeseed), nuts, corn, pea, corn products, dark green leaf vegetables, eggs, liver and viscera.
Vitamin E is considered the most stable lipophilic vitamin. There is only a minimal loss of tocopherol during food processing, these losses are approximately 10 %.
The vitamin K supports blood clotting in the human body and, along with the vitamin D, is involved in the constant bone development and remodeling.
Both foods of plant and animal origin are sources of vitamin K, such as meat, liver, milk, vegetables and fruit. The recommended daily intake of vitamin K is around 0,01 to 0,14 mg. The infants and children up to three years have lower need of vitamin K intake. The most common cause of vitamin K hypovitaminosis is disruption of intestinal microflora caused by various drugs, e.g. antibiotics. Too high doses of vitamin K can accumulate in the body and lead to the breakdown of erythrocytes, damage the liver and cause jaundice in children.
There is not much information known about the stability of vitamin K yet. It has been found that vitamin K decomposes rapidly in the light, however its losses during food processing are minimal.
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The importance of nuts in the diet
Suchá, Martina ; Hejtmánková, Alena (advisor) ; Táborský, Jan (referee)
Dry shell fruits - the nuts; are among in fruits. The most important representatives of this group are walnuts and hazelnuts, almonds, pecans, Brazil nuts, pistachios, pine nuts and cashews.
In nuts are the most fats, the average proportion of fat constitutes is about 55%. Important is also the proportion of high quality proteins (20%) and carbohydrates that are present particularly in the form of dietary fiber (12%). Also important is the presence of vitamin E, which is an important antioxidant for the body and prevents spoilage of fats. Dry shell fruits are rich in vitamin B and folic acid. With regular consumption of even small amounts of nuts is ensured adequate intake of minerals, which are located in nuts in a very significant amount. Nuts are particularly important source of magnesium, potassium, calcium, iron, zinc, copper and selenium.
Due to the high proportion of fat are nuts spoils quickly. Specific spoilage of the nuts is caused omnipresence of atmospheric oxygen it is very difficult to stop this process.
The lower storage temperature retards spoilage of nuts as well as vacuum packaging, packaging in a protective atmosphere, which prevent the access of oxygen or packaged in packaging that transmit less light.
To maintain the quality of the nuts is very important the proper drying and storage. At high water content below a shell is develops toxigenic mildew, which producing the mycotoxins. Mycotoxins are among the important natural toxins in food. The most dangerous mildew is Aspergillus flavus during their growth produces a toxin called aflatoxin. Dry shell fruits should be stored in a dry and cool place. After shelling the fruits out of the shells must be followed by rapid consumption.
Often are the nuts regarded as unhealthy for its high fat content. Recent epidemiological and clinical studies have shown that regular consumption of nuts reduces the risk of ischemic heart diseases, cardiovascular diseases, myocardial infarction, atherosclerosis and other chronic disorders.
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Determination of vitamin E in wheat different grain discoloration types
Veverková, Markéta ; Hejtmánková, Alena (advisor) ; Faměra, Oldřich (referee)
The diploma thesis deals with the determination of vitamin E in grains of wheat kernels with unusual coloring. In the theoretical part is mentioned botanical characterization of wheat, barley and tritordeum, vitamin E and its chemical and biological aspects and basics of chromatography with a focus on the high performance liquid chromatography (HPLC).
The analysis to quanify vitamin E was performed in the experimental part of the thesis. The analysis was conducted with samples of winter and spring wheat, spring barley and spring tritordeum from harvests of 2014 and 2015. These were varieties with unusual coloring of the grain. The evaluation was conducted by variety (winter wheat, spring wheat, spring barely, spring tritordeum) and by the color of the kernels (blue aleuron, purple pericarp, yellow pericarp). Subsection part of the thesis is dedicated to a quantification of vitamin E during long-term storage.
Based on the determination of total vitamin E amount in all analyzed varieties of cereal grains with a different color is not statistically significant difference in the values of the total amount of vitamin E. The difference between the content of vitamin E in the samples of the same varieties of different cereals harvest from a year 2014 and a year 2015 were not statistically significant. All varieties of wheat were quantified four vitamers: alpha-tocopherol, beta-tocopherol, alpha-tocotrienol and beta-tocotrienol. The amount of other vitamers was below the limit of detection. The total content of vitamin E and contents of individual vitamers coincide with the data given in the literature for wheat varieties with standard color of grain. Spring barley contained a slightly higher average levels of total vitamin E amount in comparison with varieties of spring and winter wheat. The total average amount of vitamin E in varieties of spring tritordeum was also slightly higher than in varieties of winter and spring wheat. From the long term storage point of view, it is clear that the total amount of vitamin E in both varieties is relatively stable and shows no clear trend in function of storage time.
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Biologically active substances contained in tea, coffee and cocoa
Marková, Kristýna ; Hejtmánková, Alena (advisor) ; Jadrná, Petra (referee)
This bachelor thesis deals with the effects and chemical structures of selected biologically active substances contained in tea, coffee, and cocoa. The tea plant (Camellia) belongs to the family Theaceae. Several varieties are cultivated, but all of them are referred to as the Camellia sinensisvariety. The main products of the tea plant are leaves from which tea is produced. Catechins (8 - 18 %) are the most meaningful substances in tea, they belong to the group of polyphenolic substances, which have strong antioxidant properties.
The coffee plant (Coffea) belongs to the family Rubiaceae. The most significant varieties from this family are Coffeaarabica and Coffearobusta; their beans are used for the production of coffee. Coffee is a sought-after stimulating beverage. Caffeine (0.7 - 2.5 %) is the most important substance, it is included in the group of alkaloids. Itis a central nervous system stimulant, affecting the heart beat and the cardiovascular system.
The cocoa tree (Theobroma) belongs to the family Sterculiaceae. A significant representative of this family is Theobroma cacao and its groups Criollo, Forastero, and Trinitario. Cocoa is particularly rich in flavonoids (20 %) which also belong to the group of polyphenolic substances. They are strong antioxidants; in adequate quantity, they have positive effects on health.
Tea, coffee, and cocoa also contain vitamins and minerals. In the organism, they may form part of a structure of somatic cells and enzymes, some of them are activators of enzymes, and they also act as molecule transporters in metabolic reactions. Vitamin C and vitamin E are most frequently present; minerals potassium and phosphorus have the highest content in these stimulating products.
The total concentration of biologically active substances is primarily affected by the family of the relevant type and form of processing. Raw materials that have not undergone fermentation or roasting contain more biologically active substances than those that have been treated.
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Monitoring the quality of fats in Czech bakery products
Pávová, Eva ; Táborský, Jan (advisor) ; Hejtmánková, Alena (referee)
The paper focuses on the quality of fats in Czech bakery products, such as bread. Even though bread contains very little fat, it plays an important role as a component of a typical Czech diet. Research has found out that there may be a correlation between the consumption of certain groups of fatty acids and an increased risk of some diseases, especially coronary heart disease. The correlation has been found to be the highest when trans fatty acid are included in the diet. Polyunsaturated fatty acids, on the other hand, have been claimed to have a positive effect on human health. It has been recommended by the World Health Organization that especially foods containing beneficial n-3 polyunsaturated fatty acids should be incorporated into the diet more. Twenty samples of different kinds of bread were used for the analysis, half of them being samples of fresh bread, the other half containing samples of thaw-and-serve goods. The study focused on analyzing the composition of the fatty acids using gas chromatography. In addition to that, the total amount of fat in the samples was estimated based on the amount of extracted fat.
27 fatty acids were analyzed in all samples. These composed over 99 % of all fatty acids in almost all samples. Monounsaturated fatty acids were found in the greatest abundance in comparison with other groups of fatty acids. The most abundant of these were linolic acid and oleic acid. All samples contained very small amounts of trans fatty acids. The levels of these were in amounts of the order of hundreds or tens of 1 %. Very different ratios of n-3 to n-6 fatty acids were observed, ranging from 0,06 - 1,74. There were no apparent differences in the data between the two groups of samples. The total amount of extracted fat was small in the majority of samples. The values for most samples were around 5 %. One sample contained over 10 % of fat after the extraction, and three samples contained less than 1 % of fat.
A conclusion can be drawn from the study that even though the amount of fat in bread is usually small, Czech bread can be a good source of high quality fat rich in unsaturated fatty acids. In addition to that, in some cases high amounts of n-3 fatty acids are present.
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