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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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Extraction of bioactive substances from the pomace of red grapes
Jandrtová, Sabina ; Pořízka, Jaromír (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis deals with the research of chosen chemical characteristics in juice and in extracts of grapevine (Vitis vinifera L.). The theoretical part is divided into three parts. In the first part is described the botanical characteristic of grapevine, then its origin, morphology, chemical composition, species and uses. In the second part are characterized anthocyanin pigments, their occurrence and attributes. There are described methods of the investigation. In the third part are described extractions. The experimental part illustrates extractions of the pomace. The purpose of these extractions is to find out the total amount of anthocyanins and phenolics in the pomace, and which solvent gives the highest yield. Then the chemical characteristics, such as total and soluble solids, pH, the amount of titratable acids, reducing carbohydrates, phenolics and anthocyanins, are described in this section. All determinations are executed and results are compared among grapevine juice and two species (Cabernet Sauvignon and Zweigeltrebe). The most suitable solvent is selected a mixture of water and ethanol in a ratio 50:50. In the most effective hours are determined the chemical characteristics. The titratable acids are expressed as the amount of the tartaric acid. The amount of phenolics is expressed as gallic acid and the amount of anthocyanins as malvidin-3-glucoside.
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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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Extraction of bioactive substances from the pomace of red grapes
Jandrtová, Sabina ; Pořízka, Jaromír (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis deals with the research of chosen chemical characteristics in juice and in extracts of grapevine (Vitis vinifera L.). The theoretical part is divided into three parts. In the first part is described the botanical characteristic of grapevine, then its origin, morphology, chemical composition, species and uses. In the second part are characterized anthocyanin pigments, their occurrence and attributes. There are described methods of the investigation. In the third part are described extractions. The experimental part illustrates extractions of the pomace. The purpose of these extractions is to find out the total amount of anthocyanins and phenolics in the pomace, and which solvent gives the highest yield. Then the chemical characteristics, such as total and soluble solids, pH, the amount of titratable acids, reducing carbohydrates, phenolics and anthocyanins, are described in this section. All determinations are executed and results are compared among grapevine juice and two species (Cabernet Sauvignon and Zweigeltrebe). The most suitable solvent is selected a mixture of water and ethanol in a ratio 50:50. In the most effective hours are determined the chemical characteristics. The titratable acids are expressed as the amount of the tartaric acid. The amount of phenolics is expressed as gallic acid and the amount of anthocyanins as malvidin-3-glucoside.
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