Presented diploma thesis is focused on analysis of phenolic compounds in various types of beers. The aim of this work was to find possible differences among several types of beers and also between Czech beers and beers of foreign production. Theoretical part contains detailed description of beer technology, review of important analytical methods for determination of phenolic compounds and total antioxidant activity. The main attention is focused on instrumental technique LC/MS. In the experimental part values of total phenolics and total flavonoids and results of antioxidant status in analyzed beers were determined spectrophotometrically. Basic brewing characteristics were determined by pycnometry. On-line liquid chromatography with photo diode array detection and mass spectrometry detection was used for identification and quantification of individual phenolic compounds. Spectrophotometric analysis of phenolic and flavonoid levels seems to be less specific, that is consistent with findings in accessible literature. It was proved, that iso- bitter compounds exhibit about 65.44 – 90.93 % of the total bitter substances. These components are responsible for the main part of beer bitterness. The HPLC/PDA/ESI-MS was necessary to use for determination of characteristic phenolic compounds in individual types of beer. Within our measurement three columns were tested, the most favourable results were obtained using the column Restek C18. When compared with foreing beers, in Czech beers higher level of majority of phenolic compounds was detected and specific distribution of individual derivatives was found as well.

The thesis deals with lignin and soluble phenolic determination in Norway spruce foliace using hyperspectral data. A literature overview is focused on the analysis of lignin and soluble phenolics. The practical part focuses on the determination of wavelenghts intervals which are suitable for the detection of lignin and soluble phenolics. There is applied regression analysis for the determination of relationship between the foliage spectra and the content of biochemical substances for the chosen spektrum intervals. Indexes NDLI, mNDLI and RLI were than calculated. HyMap hyperspectral airborne images from 2009 and 2010 for the area of Sokolov, spectral curves of dry matter and fresh branches of Norway spruce and laboratory determination of lignin and soluble phenolics content were the inputs for the analyses. Maps of lignin content in Norway spruce are the final output of the work. Keywords: Norway spruce (Picea Abies), lignin, soluble phenolics, PLS (partial least square) method, multiple Stepwise regression, NDLI

Kudzu (Pueraria lobata) is an edible vine from the legume family native to China but growing prolifically throughout the southeastern United States. Legumes are abundant in the beneficial compounds phytoestrogens, specifically isoflavones. This research analyzed Mississippi-grown kudzu roots, leaves, and flowers for antioxidant activity and total phenolic content and evaluated consumer acceptability of food products containing kudzu. Results indicated kudzu flowers, roots, and leaves contained phenolic compounds and the antioxidant activity amounts in flowers, roots, and leaves were 77.9%, 75.7%, and 56.5%, respectively. The dip products that were developed and evaluated were mayonnaise- and sour cream-based dips that contained either dried kudzu leaves or dried spinach and other seasonings. Healthier versions of dip products were developed using light mayonnaise and light sour cream and omitting salt. Consumer sensory panels evaluated appearance, aroma, flavor, texture, and overall acceptability of the dip samples using a 9-point hedonic scale. A randomized complete block design with three replications was used to determine if differences (p<0.05) in consumer acceptability existed among treatments. On average, the regular spinach dip was moderately liked and preferred (p<0.05) over the other dips. The regular kudzu dip was moderately liked and preferred (p<0.05) over the healthier kudzu and spinach dips. Cluster analysis partitioned consumers into five groups based on preference and acceptability of vegetable dips. Results indicated 39% of panelists rated the dips at like very much and did not differ (p>0.05) in their liking of dips, 42% preferred (p<0.05) the regular spinach dip and 50% liked all vegetable dips. A kudzu blossom jelly product was developed using kudzu flower liquid, sugar, pectin, and lemon juice. Consumer sensory panels evaluated the prepared jelly product, a purchased kudzu jelly, and a purchased scuppernong jelly. A randomized complete block design with three replications was used to determine if differences (p<0.05) in consumer acceptability existed among jellies. The purchased kudzu jelly was preferred (p<0.05) for overall acceptability (like moderately) compared to the prepared kudzu and scuppernong jelly, which were rated similarly between like slightly and like moderately.

This study evaluated the nutritional and antioxidant properties of Sesamum indicum, Cucumeropsis edulis and Cucurbita pepo seeds by determining proximate composition and mineral composition by atomic absorption spectroscopy and antioxidant assays. C. pepo had the highest protein (28.31%), S. indicum had the highest fat (52.53%) and C. edulis had the highest fiber content (6.23%), and highest total antioxidant capacity (199.75 mg AAE g−1 dry weight of ethanol extract). Magnesium, potassium, iron, calcium, sodium and zinc were the most abundant mineral elements present in these seeds.

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Flavonoids are plant secondary metabolites that play diverse roles in plants and human health. These compounds in most part exist in the glucosylated form. Grapefruit accumulates high levels of glucosylated flavonoids. Plant secondary product glucosyltransferases (GTs) catalyze the glucosylation reaction, but due to low homology at both the nucleotide and amino acid sequence level of different GTs, it is not possible to ascribe function based on sequence only. The hypotheses that PGT clones 9 and 11 are plant secondary product GTs and are biochemically regulated were tested. PGT 9 has been cloned into Pichia pastoris using the pPICZA and pPICZAα vectors, expressed, enriched, and screened for GT activity with a variety of phenolic substrates. Initial screens show catechol, gentisic acid, vanillin, and p-hydroxylphenylacetic acid as potential substrates for the PGT 9 protein. PGT 11 has been successfully cloned into pPICZA for transformation into yeast, expression, and subsequent characterization.

The grapefruit plant, Citrus paradisi, tends to accumulate high levels of flavonoid glycosides such as flavanones and flavones. Flavonoids have a vast array of important functions in plants and also in humans. Glucosyltransferases (GTs) are enzymes responsible for glucosylation reactions. In our pursuit to study the structure and function of flavonoid GTs, we have used molecular approaches to identify, clone, express, and functionally characterize the enzymes. This research was designed to test the hypothesis that PGT3 is a flavonoid glucosyltransferase and is subject to biochemical regulation. PGT3 has been tested for GT activity with compounds representing subclasses of flavonoids as well as some simple phenolics. Results indicate GT activity with 6 substrates, p-hydroxybenzoic acid, vanillin, vanillic acid, p-hydroxyphenylpyruvate, gentisic acid, and catechol. A second project designed to clone putative PGT8 into the Pichia expression system has been completed.

In response to increasing interest in greenhouse production and difficulties imposed by adverse environmental conditions in the southeastern United States, two studies were conducted with green and red-leaf lettuce cultivars. The first study analyzed effects on yield and quality of green and red-leaf lettuce subjected to increasing nutrient solution electroconductivity (EC) across three growing seasons. Results indicated that the interaction between season and cultivar had the greatest effect on growth, flavonoids and phenolics, and leaf mineral content. The second study analyzed effects on yield and quality of increasing solution potassium (K) in red Lollo lettuce at two temperatures. The results suggested that temperature is a stronger regulatory factor than increasing K in the determination of lettuce yield and quality. However, increasing K concentrations to 234.6 mg·L-1 results in higher concentrations of leaf mineral concentrations without compromising lettuce yield and quality.

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