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Study of the quality of oilseeds in bread products
Fučík, Jiří ; Pořízka, Jaromír (referee) ; Vespalcová, Milena (advisor)
This bachelors thesis focuses on analysis of crude oils pressed from oil seeds commonly used in bread products. Analysis of oils is made on different heat treated samples of seeds and commercial available oils. In the theoretical part is described the bread-making technological steps and processes, characterized oil seeds used in bread-making and oils from these seeds. In addition there is a description of experimental techniques and used types of quantitative analysis: saponification number, acidic number, ester number, iodine number and peroxide number. In the experimental part was analysed in total three samples of commercial available oils (flaxseed, sesame, sunflower) and three samples of oils pressed from fresh oil seeds (flaxseed, sesame, sunflower). Seeds were also baked in the bread, pressed and analysed. Results of each sample preparation phase was compared and possible change justified.
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Influence of beer protein on foam stability
Benda, David ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This bachelor thesis deals with the influence of beer proteins, phenolic compounds, bitterness and selected metal ions on beer foam stability. The theoretical part describes beer foam from the physical aspect, beer foam stability and its measurement and the factors that positively or negatively influences the stability and quality of the beer foam. In the theoretical part are described selected proteins that influence beer foam. In theoretical part is described the origin and technological significance of proteins. The experimental part is dedicated to the measurement of beer foam stability with the NIBEM method, the analysis of total protein content, the analysis of total phenolic content, bitternes and element analysis of beer samples. Measured data indicated correlations between protein content, phenolic compounds content, bitterness and metal ions with the beer foam stability. The results show that proteins and phenolic compounds as isolated parameters don’t essentialy affect the beer foam stability. It was found out, that bitterness as isolated parameter influences the beer foam stability the most.
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Production and characterization of protein isolates from different kinds of bran
Vybíral, Lukáš ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deals with the use of various types of bran as a by-product in the milling of cereals. Mills create a huge amount of this material per year. The most common way of processing bran is mostly incineration and to a lesser extent it is used as feed for livestock. Depending on the type of cereal, bran contains 10-20% of protein, which disappears from the food chain due to combustion. Within the framework of sustainability and valorisation of waste, which has recently been largely discussed, great emphasis is placed on waste minimization whether in the field of its production or further processing. Due to the relatively high protein content, bran appears to be a suitable starting material to produce protein supplements. Proteins can be extracted from bran based on their different solubility at different pH. In the alkaline method, the proteins are first dissolved in an alkaline pH and then precipitated in an acidic medium. Lyophilization is followed by characterization of the extract in terms of yield, protein content, moisture, amino acid profile and digestibility. The highest yield was obtained with the oat bran isolate (13,5 ± 0,6 g of isolate per 100 g of bran). In terms of protein content, the best protein isolate was also obtained from oat bran (95,2 ± 0,4% protein in the isolate). Another determination was the analysis of the amino acid profile, in which a high content of arginine was found in all analyzed protein isolates from bran. Determination of digestibility showed very good digestibility of all produced protein extracts from bran.
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Development and characterization of new dairy products with increased fiber and protein content
Smatana, Igor ; Punčochářová, Lenka (referee) ; Pořízka, Jaromír (advisor)
The bachelor thesis was focused on the production and characterization of new dairy products with increased protein and fiber content. Ground wheat bran was used as the fiber source and wheat bran protein extract was used as the protein source. From an ecological point of view, it would be ideal if 100% of the raw material was used and nothing was left as waste. We tried to approach this by using the waste (by-product) that arises during the production of flour as an additive to dairy products. The theoretical part focused on the characterization of fermented and unfermented dairy products and their production, the nutritional value of proteins and fiber and the composition and benefits for human health of wheat bran, protein isolation from wheat bran and common analytical methods to determine rheological properties, viable cell numbers. water binding and sensory acceptability. Two basic dairy products were created, one fermented and one unfermented, and subsequently fortified with a source of fiber (wheat bran) and a source of protein (protein concentrate from wheat bran). All products were subsequently characterized for characterization. Water binding, rheological and sensory properties were determined. The fermented dairy product was also subjected to cytometric analysis to determine the number of viable cells. The experimental part describes the methods we use to prepare and characterize new products. After evaluating the measured data, options for optimizing the acceptability of products by consumers were proposed. The results showed that the organoleptic properties were negatively affected by the addition of wheat bran and protein concentrate.
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Study of the chemical processes during kombucha technology
Chludilová, Markéta ; Obruča, Stanislav (referee) ; Pořízka, Jaromír (advisor)
The kombucha drink is referred to as leavened tea with added sponge called a scobie. In this way, a low-alcohol beverage is obtained, which gains considerable popularity, especially due to the alleged beneficial properties for human health. The microbial composition of this beverage is very rich, consisting of bacteria and yeasts living in a beneficial symbiosis [11]. The microbial composition of the drink and its beneficial effects on human health are very closely related. This work deals with the analysis of the chemical composition of the commodity beverage, especially with regard to the content of major components such as organic acids, carbohydrates and ethanol. These analytes are among the most common and most profoundly found substances in the carbohydrate beverage and are very closely related to the microbial composition of the scoby itself [3]. Combo beverage samples were supplied by RebornFood, one of which is the commercial production of this drink on the Czech market. At the same time, this company bases itself on purely natural fermentation of beverages, and therefore it is not particularly involved in the production process. The results of this diploma work point to the effect of the scoby used and the associated occurrence of analytes in the beverage, as well as the production process associated with the formation of analytes, which is described in several articles. It is expected that this work will provide information both on the production conditions and on the chemical properties of the beverage related to the condition of the scoby, which will be used further, both for RebornFood and the material used to solve the technical problems of this beverage production.
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Analysis of wine by modern analytical methods
Škařupa, Přemysl ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
This work is dedicated to the analysis of wines using modern analytical methods. The theme is divided into two chapters. The first part deals with the chemical composition of wine from major components to the elements in trace amounts. The second part gives an overview of the most important modern analytical methods used for analysis of individual compounds in the wine and evaluated these methods in term of various parameters.
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Beer foam stabilization using biosurfactants
Jandrtová, Sabina ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis focuses on a research of the foam stability of the beer. We specifically observed the influence of ethanol and surface tension on the foam stability, and influence of ethanol and surface tension on the height of the foam. It was observed the influence of the hop acids in non-alcoholic beers. Furthermore, different biosurfactants were added into to the beer to observe better stability of the foam. The theoretical part of this work describes the foam from the physical aspect. There are described fourth key events involved in foam formation. Then it focuses on the beer foam – its structure, substances that influence its behavior and measurement of the foam stability. In this part there are described biosurfactants as well – their characteristics, qualities, distribution and applications. The experimental part is dedicated to the influence of ethanol, surface tension, the amount of iso- acids on foam stability in beer. There is observed the influence of biosurfactants of the foam stability and surface tension, which are added into to the beer. For the measurement of the foam stability was used the Rudin method. Liquid chromatography with DAD detector was used for the measurement the amount of the hop acids. The surface tension was determined by tensiometer. According to the results addition of ethanol changed the characteristics of the foam stability, but it’s not easy to find correlation between the increasing amount of ethanol and its stability. It was found out, that there is connection between the amount of ethanol and surface tension. On the other hand, there is not much connection between the surface tension and foam height. Within the framework of addition of biosurfactants was observed, that these foaming agents interacted the surface tension of the beer (lowering), however these agents accelerated the fall of the beer foam.
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Determination of sweeteners and preservatives in energy drinks by HPLC
Zídková, Anežka ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
This master´s thesis is focused on simultaneous determination of sweeteners and preservatives in energy drinks by liquid chromatography coupled with DAD and ELSD detection. The method was optimized for determination of aspartame, acesulfame K, saccharin, sucralose, steviol glycosides, benzoic acid and sorbic acid. Analyses were carried out on the Poroshell 120 EC-C18 column (4.6 x 150 mm, 2.7 m, Agilent) using mixture of methanol, acetone and water with formic acid and trimethylamine as a gradient mobile phase at a flow rate 0,5 mL•min-1. Validation parameters were determined (limit of detection, limit of quantification, repeatability and recovery). The validated method was applied on real samples.
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Developement and optimization of the method for the extraction of ferulic acid from wheat bran
Hubačová, Klára ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
Bachelor thesis is considering usage of wheat bran for an extraction of ferulic acid. Wheat bran is a large-scale by-product of milling industry which is produced during milling of cereals (wheat) into flour. This low-cost product is usually used as a livestock feed. An initiative is raised for some other potential applications, because too large quantity produced every year can not be consumed just as a feed. There is a significant amount of phenolic acids from which ferulic acid is the most abundant one. It was found out after examination of structure of the wheat bran. This acid is connected with polysaccharides of a cell wall. The alkaline hydrolysis was used to disrupt a linkage between ferulic acid and polysaccharides. Then ethanol was added to precipitate the polysaccharides and the mixture was filtered. The filtrate contains ferulic acid which has great health benefits such as anti-inflammatory, antioxidant, anti-carcinogenic, antimicrobial effect etc. It plays an important role as an agent against UV radiation in the cosmetic products.
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The ecological grape and wine production
Kalábová, Jana ; Pořízka, Jaromír (referee) ; Omelková, Jiřina (advisor)
Bachelor´s thesis is focused on technological processes of production of wine and now very mature producing organic wines. It describes the principles of organic farming and organic way of growing grapes. It provides basic information about grape wine, which is an important raw material for wine production. It refers also to the modern protection of ecologically grown plants from fungal diseases and pests. The aim of experimental part was to examine the effects of aqueous extract of dried sage to the growth of microorganisms. Sage contains protective substances effective in preventing of pests. The results showed, that the extract from the stems showed inhibitory effect on some selected microorganisms, but the extract from the leaves did not show inhibition.
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