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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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Srovnání antioxidačních vlastností a absorbce UV záření u extraktů vybraných bylin, Spiruliny a jejich směsí
Farinasso, Giulia
This study aimed to compare the antioxidant properties and UV radiation absorption of se-lected herbal extracts, blue-green algae spirulina extract and their mixtures. Extracts were ob-tained by ultrasound assisted extraction. The total polyphenol (TPC) and flavonoid contents (TFC) were determined, and the Trolox equivalent antioxidant capacity (TEAC) was meas-ured. The best antioxidant properties has been showed by C. officinalis individual extract and its mixture with spirulina. Additionally, the UV-absorbing substances at 355 nm were quanti-fied. The extracts from C. officinalis and S. nigra were further analysed for their rutin content by HPLC-DAD. The rutin content in S. nigra and C. officinalis extracts was found to be 1935,97 ± 98,39 μg.g-1 and 233,035 ± 8,839 μg.g-1 of dry weight of flos, respectively. The highest content of phenolic compounds was found in the S. nigra extract, and the highest total antioxidant capacity was determined for the C. officinalis extract. Pearson's correlation re-vealed that the overall antioxidant capacity and UV absorption results were significantly cor-related with the total phenolic compound content only for the elderflower extract. The syner-gistic effect of the herbs used in combination with spirulina was evaluated.
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Antioxidant system of tomato plants exposed to triazole fungicides
Žufić, Antoniana ; Hýsková, Veronika (advisor) ; Jaklová Dytrtová, Jana (referee)
Fungal pathogens cause severe crop losses worldwide. Recently, however, chemical fungicides have become dangerous environmental contaminants affecting non-target organisms. The aim of this study was to investigate the effect of triazole fungicides in the form of penconazole (P), tebuconazole (T) or their combination (PT) on tomato plants Solanum lycopersicum L. cv. Cherrola. No significant change in the activity of a key enzyme of the ascorbate-glutathione cycle, ascorbate peroxidase and activity of cytosolic peroxides, was detected in leaves, roots or fruits at the intervals studied, i.e. after two and five weekly treatments of P, T or PT, either as a foliar or a soil application. While slightly increased guaiacol peroxidase activity was found in roots due to T spraying and PT combination, the activity of this enzyme was reduced in leaves similar to catalase. The greatest changes in leaf antioxidant capacity correlated with increased phenolic and flavonoid content were observed after five treatments of penconazole (P) as a soil application both P alone and in combination as PT. The studied triazoles significantly affected the abundance of isoforms of superoxide dismutase and partially total peroxides in leaves, roots and fruits and of acorbate peroxidase in leaves. The highest content of HSP70 was found in...
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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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