The objective of this thesis was to investigate the content of polyphenols in these juices: apple from concentrate, apple produced by direct compression, orange with pulp, orange without pulp, grapefruit from concentrate, juice from red grapes, pomegranate and purple carrots. The measurement was taken by high performance liquid chromatography and mass spectrometry. The polyphenol with the highest overall value and also the most important of polyphenols in citrus juices was hesperidin. Significant content of cryptochlorogenic acid and hyperoside was in apple juice. Apple juice produced by direct compression also contained a lot of catechin. Epigallocatechin, epicatechin and gallic acid were substances with the highest value measured in the juice of the pomegranate. Catechin, epicatechin and epigallocatechin were most prevalent in the grape juice. Quantitatively the most important compounds of juice from purple carrots were caffeic and cryptochlorogenic acid.

This diploma thesis was focused on study of low-molecular antioxidants present in various kinds of fruits, namely berries. In theoretical part detailed characterization of antioxidants studied in presented work and their biological effects are introduced. Further, principals of processing and storage of specified species of fruits are discussed. Changes observed during storage of specific fruits are described too. In practical part changes in content of selected antioxidants in berries were followed. As studied material strawberries, raspberries, blueberries, red and black currants were used. All kind of these fruits was stored in fridge for six months using several different kind of processing. Berries were stored as whole fruits, whole osmotically processed fruits by sucrose, raw pulp and sweetened pulp. At first, starting values of selected antioxidant parameters were measured in fresh fruits (ascorbate, total antioxidant activity, total phenolics, catechins and individual flavonoids). After freezing the same parameters were measured regularly in two month periods. As the most suitable method of fruit processing, with regard to antioxidant content, storage of the whole fruits or pulp can be recommended. Content of ascorbate decreased in all forms and species of the processed fruits during all the time of storage. Oppositely, the content of other studied antioxidants exhibited fluctuations or increasing trend. Sensory analysis was proved for the whole fruits and also for whole sweetened fruits.

Introduction: This thesis investigates the effect of isolated epigallocatechin-3-gallate on weight reduction in the adult population. An overview of Czech and foreign literature was provided on topics of obesity, the possibility of using green tea in its treatment and the positive effects of green tea on human health, followed by a systematic review and meta-analysis. Methodology: Using a three-phase systematic search strategy, published studies were searched in the Scopus database using predefined keywords. The aim of the search was to find randomized placebo-controlled studies lasting at least 8 weeks, which examined the effect of isolated EGCG in the absence of other active substances on the change of body parameters. The extracted data from the primary studies were then evaluated using meta-analysis and forest plot. As a result, a standardized mean difference with a 95 % confidence interval was calculated using a random effect model. Results: Six1 studies met the inclusion criteria, one2 of which was excluded due to insufficient evaluation in the critical appraisal of methodological quality. The remaining 5 studies provided a total sample of 325 participants who were diagnosed with a change in BMI induced by EGCG consumption. The result was a standardized average difference of -0.01, 95 % CI:...

In theoretical part of this diploma thesis the basic properties of antioxidants, especially anthocyanins and phenolic compounds are described, as well as the basic features and principles of free radicals formation. The theoretical part also describes some possible ways of encapsulation of antioxidants into polysaccharide and lipid particles. In the experimental part basic characteristics of extracts from selected lyophilized fruits and vegetables (carrots, apples and mixed berries) are described. As group parameters of plant extracts the total antioxidant activity, content of flavonoids and phenolics, carotenoids, anthocyanins and ascorbic acid were determined. In experimental part also various encapsulation techniques were tested, encapsulation effectiveness of each technique was evaluated and the stability and size of the created particles were determined. As the best encapsulation method in terms of encapsulation efficiency in most of samples/parameters ethanol injection was found. On the other hand the particles prepared by ethanol injection are relatively unstable in terms of zeta potential, which is followed by their tendency to aggregate. As the most stable particles prepared by thin layer evaporation (TLE) and reverse phase thin layer evaporation (RP-TLE) were evaluated. Particles prepared by TLE, RP-TLE and chitosan-alginate particles exhibited a negative charge, while particles prepared by ethanol injection stayed uncharged and chitosan particles have a positive charge.