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Isolation of lignin from grape seeds and its application as filler for polyhydroxyalkanoates (PHA)
Vostrejš, Pavel ; Vítová, Eva (referee) ; Kovalčík, Adriána (advisor)
This diploma thesis deals with 1) the preparation of biodegradable polymer films based on polyhydroxyalkanoates (PHA) and 2) their modification by lignin as an active additive. The motivation for this work was to prepare active packaging material for food packaging. Polymer films were prepared by blending of neat crystalline poly(3hydroxybutyrate) (P3HB) and amorphous polyhydroxyalkanoate (PHA). The lignin was isolated from grape seeds derived from grape pomace. The solubility of lignin in chloroform was improved by acetylation. The properties of the isolated lignin were determined by elemental analysis, ash content, and infrared spectroscopy (FTIR). Lignin was used as an active additive for the modification of polymeric films prepared by solution casting of P3HB or P3HB blended with amorphous polyhydroxyalkanoate. The effect of different concentrations of lignin in the range of 1 to 10 % was tested. The lignin type and concentration had a different influence on the final thermal and mechanical behaviour of polymeric films. Lignin increased the values of the Young modulus and tensile strength of the prepared films. Differential scanning calorimetry data confirmed that lignin positively modified crystallization kinetics of P3HB. Thermogravimetry was used to analyse the thermal stability of PHA films. Lignin markedly increased the thermal stability of PHA films. However, acetylated lignin harms the mechanical properties of films. Moreover, this work showed that lignin isolated from grape seeds and added into PHA films proved its high antioxidant capacity. PHA films with lignin displayed much better gas barrier properties compared with PHA films without lignin. The prepared bioactive PHA films fulfil the requirements for sustainable food packaging with high antioxidant capacity and excellent gas barrier properties.
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Impact of nitrogen fertilization and drought on glutenins content in winter wheat
Vostrejš, Pavel ; Vítová, Eva (referee) ; Hrstka, Miroslav (advisor)
In this bachelor thesis the effects of nitrogen fertilization and drought stress on glutenin fraction of winter wheat (Triticum aestitivum L.) were studied. Winter wheat cultivar Tiguan was grown under different rainfall mode, on the one hand in drought (DRY), on the other hand in normal downfall (WET). Part of the samples was treated with nitrogen fertilization at a dose of 140 kg / ha (N140), the other part remained without fertilization (N0). After the gliadins were separated, the glutenins from the samples were extracted with 50% isopropanol with 1% DTT. Individual glutenin fractions were separated by SDS-PAGE and quantified by computer densitometry. The drought did not have a statistically significant effect on any of the glutenin subunits. Nitrogen fertilization caused an increase in the total amount of glutenin as well as the amount of individual subunits. Interaction of water regime treatment and fertilization has not led to an increase in glutenin levels in HMW 3 GS and LMW 5 GS in DRY conditions.
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Isolation of lignin from grape seeds and its application as filler for polyhydroxyalkanoates (PHA)
Vostrejš, Pavel ; Vítová, Eva (referee) ; Kovalčík, Adriána (advisor)
This diploma thesis deals with 1) the preparation of biodegradable polymer films based on polyhydroxyalkanoates (PHA) and 2) their modification by lignin as an active additive. The motivation for this work was to prepare active packaging material for food packaging. Polymer films were prepared by blending of neat crystalline poly(3hydroxybutyrate) (P3HB) and amorphous polyhydroxyalkanoate (PHA). The lignin was isolated from grape seeds derived from grape pomace. The solubility of lignin in chloroform was improved by acetylation. The properties of the isolated lignin were determined by elemental analysis, ash content, and infrared spectroscopy (FTIR). Lignin was used as an active additive for the modification of polymeric films prepared by solution casting of P3HB or P3HB blended with amorphous polyhydroxyalkanoate. The effect of different concentrations of lignin in the range of 1 to 10 % was tested. The lignin type and concentration had a different influence on the final thermal and mechanical behaviour of polymeric films. Lignin increased the values of the Young modulus and tensile strength of the prepared films. Differential scanning calorimetry data confirmed that lignin positively modified crystallization kinetics of P3HB. Thermogravimetry was used to analyse the thermal stability of PHA films. Lignin markedly increased the thermal stability of PHA films. However, acetylated lignin harms the mechanical properties of films. Moreover, this work showed that lignin isolated from grape seeds and added into PHA films proved its high antioxidant capacity. PHA films with lignin displayed much better gas barrier properties compared with PHA films without lignin. The prepared bioactive PHA films fulfil the requirements for sustainable food packaging with high antioxidant capacity and excellent gas barrier properties.
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Impact of nitrogen fertilization and drought on glutenins content in winter wheat
Vostrejš, Pavel ; Vítová, Eva (referee) ; Hrstka, Miroslav (advisor)
In this bachelor thesis the effects of nitrogen fertilization and drought stress on glutenin fraction of winter wheat (Triticum aestitivum L.) were studied. Winter wheat cultivar Tiguan was grown under different rainfall mode, on the one hand in drought (DRY), on the other hand in normal downfall (WET). Part of the samples was treated with nitrogen fertilization at a dose of 140 kg / ha (N140), the other part remained without fertilization (N0). After the gliadins were separated, the glutenins from the samples were extracted with 50% isopropanol with 1% DTT. Individual glutenin fractions were separated by SDS-PAGE and quantified by computer densitometry. The drought did not have a statistically significant effect on any of the glutenin subunits. Nitrogen fertilization caused an increase in the total amount of glutenin as well as the amount of individual subunits. Interaction of water regime treatment and fertilization has not led to an increase in glutenin levels in HMW 3 GS and LMW 5 GS in DRY conditions.
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