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Determination of the effect of dog rose (Rosa canina L.) on the oxidative stability in fresh juices
Borová, Šárka ; Mikulíková, Renata (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis aimed to determine the content of bioactive substances and antioxidant activity in ethanolic extracts of rose hips fruits (Rosa Canina L.). This work verified the possibility of using the rosehip ethanolic extract as an antioxidant to inhibit the oxidation of fresh pear juice. The ethanolic extracts were prepared by extracting rose hips fruits in various ratios of fruits to the volume of 40% ethanol for 7-28 days. After determining the total content of carbohydrates, polyphenols, flavonoids and vitamin C, it was found that, in principle, the range of the defined substances increases with the ratio of rosehip fruit to the volume of ethanol solution as well as with the extraction time. Ethanol rosehip extracts have also been shown to possess significant-high antioxidant activity. The stabilizing effect of rosehip fruit extract against the oxidation of fresh pear juice was determined spectrophotometrically. It was found that rosehip fruit extracts could inhibit the oxidation of fresh pear juice and have the potential as a natural stabilizer of fresh fruit juices.
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Bacterial cellulose based facial mask with antioxidant property
Borová, Šárka ; Hoová, Julie (referee) ; Kovalčík, Adriána (advisor)
This final thesis deals with the preparation of a cosmetic facial mask based on bacterial cellulose. The motivation of this work was to prepare a cosmetic mask with antioxidant properties. To obtain bioactive substances with antioxidant activity, extracts from the rosehip fruits (Rosa Canina L.) with different weight dosages of rosehips and different preservatives were prepared. These rosehip extracts were subjected to spectrophotometric methods, thanks to which the total contents of polyphenols, flavonoids and total antioxidant activity were determined. It was proven that the content of the determined substances increases with the proportion of weighted rose hips and the highest contents of antioxidant substances were measured in extracts with a weight of 25 g of rose hips. Subsequently, these selected extracts were modified into several samples of bacterial cellulose. After the modification of the substances, it was demonstrated that bacterial cellulose is a suitable material for absorbing bioactive substances into the structure of individual analyzed samples. It was found that bacterial celluloses in the form of hydrogel and lyophilized bacterial cellulose were able to absorb the largest amount, of bioactive substances with antioxidant properties. On the other hand, the samples of dry bacterial cellulose and bacterial cellulose with an alginate component absorbed active substances the least. Furthermore, analysis using a Visioscope device revealed that the facial cosmetic mask based on bacterial cellulose in the form of hydrogel could potentially have not only antioxidant but also hydrating effects on the skin.
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Determination of the effect of dog rose (Rosa canina L.) on the oxidative stability in fresh juices
Borová, Šárka ; Mikulíková, Renata (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis aimed to determine the content of bioactive substances and antioxidant activity in ethanolic extracts of rose hips fruits (Rosa Canina L.). This work verified the possibility of using the rosehip ethanolic extract as an antioxidant to inhibit the oxidation of fresh pear juice. The ethanolic extracts were prepared by extracting rose hips fruits in various ratios of fruits to the volume of 40% ethanol for 7-28 days. After determining the total content of carbohydrates, polyphenols, flavonoids and vitamin C, it was found that, in principle, the range of the defined substances increases with the ratio of rosehip fruit to the volume of ethanol solution as well as with the extraction time. Ethanol rosehip extracts have also been shown to possess significant-high antioxidant activity. The stabilizing effect of rosehip fruit extract against the oxidation of fresh pear juice was determined spectrophotometrically. It was found that rosehip fruit extracts could inhibit the oxidation of fresh pear juice and have the potential as a natural stabilizer of fresh fruit juices.
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