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Changes of enzyme activities in fruits during long-term storage
Ferdová, Jitka ; Melounová,, Jitka (referee) ; Márová, Ivana (advisor)
This study is focused on study of changes of enzyme and low-molecular weight antioxidants in different fruits during long-term storage. In theoretical part individual low-molecular weight antioxidants and enzymes are described. The main causes of fruit decay and some possibilities of fruit preservation and storage are summarized. As biological material some common fruits were chosen - green and red apples, peaches, plums and white grapes. The fruits were stored in laboratory, cellar, in refrigerator and in freezer. In freezing experiments some ways of fruit preparation and processing were tested and their influence on fruit antioxidant status was compared. Shortened storage experiment was applied on blueberries, cranberries, raspberries and strawberries too. In fruits some group parameters – total antioxidant status, dry mass content, ascorbate level, total flavonoids and total phenolics were analyzed spectrophotometrically. Individual flavonoids and phenolics were determined by RP-HPLC/UV-VIS and on-line LC/PDA/ESI-MS. Antioxidant enzyme activities (superoxide dismutase SOD, catalase CAT, polyphenol oxidase PPO and lipoxygenase LOX) were measured by spectrophotometry. The surface microscopy and cultivation of moulds from fruit surface were performed too. Influence of storage conditions on biological activities is dependent on fruit sort. Freezing is the most suitable procedure for long-term storage without significant changes of active substance content. Long-term storage in controlled temperature conditions and/or atmosphere is usable for fruits with longer storage period. In these fruits stabile levels of antioxidant enzymes are stored for relatively long time. Some of enzymes act synergistically. Enzyme activities differed according to storage phase; at the beginning mainly high SOD and LOX activities were observed. CAT and PPO are probably activated as defence systems in rippened and/or damaged fruits. Levels of total as well as individual low molecular weight antioxidants varied during storage in all sorts, generally, increased course with longer storage period can be observed.
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Assessment of aroma active compounds in chosen fruit types
Frechová, Vendula ; Vespalcová, Milena (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the determination of aroma compounds in selected species of less known fruits (sea buckthorn, cornelian cherry, rowanberry, medlar, japanese quince and chokeberry). The theoretical part is focused on the description of these plants, their chemical composition, possibility of utilization and processing. Aroma compounds were identified and quantified in experimental parts. The aroma compounds were extracted by solid-phase microextraction and analysed by gas chromatography. A total of 45 compounds were identified. This compounds included 17 alcohols, 9 ketons, 8 aldehydes, 6 acids and 5 esters. Concurrently, the sensory evaluation of these fruits was carried out. The profile test and evaluation using graphical scales were used for evaluation of pleasantness and intensity of taste and odour.
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Fortification of selected cereal products
Hurtová, Jana ; RNDr.Renata Mikulíková, Ph.D. (referee) ; Márová, Ivana (advisor)
Present diploma thesis describes the study of bioactive compounds in the cereals. The work is focused on possible fortification of cereal products in order to increase nutritional value of final products which is reduced during the food processing and storage. Cereal grains are rich in several phenolic compounds, vitamins and minerals that reduce the risk of chronic diseases. The aim of this study was the preparation and analysis of model fortified cereals using lyophilized fruit originating from Czech Republic. A comparative analysis of content of bioactive substances in commercial and fortified products for children was performed too. The experimental part deals with a content of individual flavonoids by RP-HPLC/UV/VIS method, spectrophotometric determination of total and reducing saccharides and analysis of mono- and disaccharides by the HPLC/RI method as well. Differences in the content of individual flavonoids and saccharides after the application of acid hydrolysis of samples were investigated. The content of these compounds increased in most products because of their release from glycosidic forms. Presence of phenolics was confirmed in all analyzed cereals. Addition of 10% of lyophilized fruit/vegetable preparative (carrot, berries, apples) caused several fold increase of phenolics content in model mixtures. In commercially available cereal products there are relatively high differences in total phenolics content, proportionally to fruit component amount. The work included the spectrophotometric analysis of total polyphenols and flavonoids in a model physiological environment (artificial stomach juice) in which the hydrolysis of bound phenolic compounds occurred. The results of this study show that addition of lyophilized fruit seems to be a good way to increase the nutritional value and maintain the content of bioactive compounds in cereal products.
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Sušárny ovoce v přidružené lesní výrobě
Peterka, Lukáš
The aim of this final thesis is to emphasize the advantages of using classic drying ovens in order to find out what types of drying ovens exist, describe them, and propose an optimal solution. The work is focused on the construction of old dryers that do not need electricity or other fossil energetic sources, possible to be built on owned or leased land. Based on the gained knowledge, the alternative proposal was designed and can be adapted and can be adapted to the time, financial and also professional requirements of its implementation. The work contains a small analysis of the purchased products associated with forest industry. The economic aspect is also taken into account in order to get an awareness of costs and possible profits. The goal is therefore to provide the inspiration for an alternative or additional use for the owners of small or a larger forest lands. The main contribution of this work is the alternative design of the dryer, its budget and plan, which is possible to implement for a better farming management.
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Zhodnocení podnikatelského prostředí s návrhem na zkvalitnění a vyšší komercializaci produktů z oblasti Arba Minch v Etiopii
Stojanović, Jovana
The presented master thesis deals with the analysis of the business environment of the fruit market in southern Ethiopia. The aim of this thesis is to evaluate the current status of the business environment of selected products and suggest its improvement in the Arba Minch district. The thesis is divided into theoretical and practical parts. The theoretical part is focused on the business environment in general, and the basic characteristics of Ethiopia (economic, social, cultural, and political). It also deals with the importance of the agricultural sector of Ethiopia (structure, production, problems, etc.). Part of the thesis is devoted to the description of the Arba Minch district of interest and development projects. The practical part evaluates the overall quality of the business environment of Ethiopia. Furthermore, the practical part is based on the results of a self-administered questionnaire survey among Ethiopian businessmen and farmers involved in fruit sales or production in the study area.
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Metody nanášení hydrogelů na povrch ovoce a zeleniny
Hrabová, Martina
The aim of this thesis was to develop a methodology for applying biopolymer mixtures directly onto the surface of selected fresh foods, fruits and vegetables, and to evaluate the prospects of biopolymer mixtures based on egg white. The theoretical part of this thesis outlines the issue of the packaging industry and the causes of food spoilage. Furthermore, methods for the application of biopolymeric coatings and films on a laboratory scale are described and natural polymers are summarized. In the experimental part of the thesis, the most suitable coating mixture was selected regarding the evaluation of strawberry and cucumber samples’ coating made of different biopolymeric mixtures. For this coating mixture, the samples of fruit and vegetable were subjected to analysis by near infrared spectroscopy.
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Stanovení biologicky aktivních látek v čerstvých ovocných šťávách
Františová, Gabriela
Fruit is a valuable source of biologically active compounds. These compounds are often contained in minor amounts. A large proportion in fruit is made up of carbohydrates. In this work, the contents of vitamin C, polyphenols, flavonoids, glucose, fructose and sucrose in fresh fruit juices were determined. Aronia, strawberries, josta, raspberries, blackberries, white and blue grapes, white and red currants were obtained from a private garden, blueberries were collected in the wild. The vitamin C and carbohydrate concentrations were determined using HPLC. The total polyphenol and flavonoid contents were measured using spectrophotometry. Of the biologically active compounds, polyphenols were the most abundant in the fruit juices. The highest contents of polyphenols and flavonoids were detected in aronia (7905.81 ± 622.65 mg/l and 4714.82 ± 667.37 mg/l). Josta was the most significant source of vitamin C (721.90 ± 1.79 mg/l). Fructose in white grapes was the highest concentrated compound (93.81 ± 3.74 g/l). The highest glucose content was detected in aronia (83.95 ± 4.80 g/l) and white grapes (90.94 ± 3.48 g/l). Sucrose was detected in strawberries, gooseberries and raspberries.
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Food as Representation: Multimodal Analysis of Food Photos on Czech Instagram
Peschková, Jana ; Váša, Ondřej (advisor) ; Marcelli, Miroslav (referee)
The aim of this thesis is to investigate how food can function as a sign, how it can represent certain values and what connotations can be associated with it. Food is currently a widespread phenomenon that acquires other meanings in addition to its basic biological function. This thesis will focus on investigating how food works within culture and what connotations are associated with it. The analysis is focused on photos of Czech food bloggers. Photos shared on social networks contain more layers of meaning than is apparent at first glance. The thesis is based on visual analysis, it focuses on individual signs, but also on the contradictions that arise as a result of their use. The thesis examines representation, which is why a parallel with the tradition of depicting food in still life is also included here. Other attributes examined in terms of food are the connection with leisure time, social status and gender. The first part of the thesis is devoted to food as a symbol and its placement in the various areas of culture. The central part of the thesis is the analysis. The default method is multimodal analysis of Instagram accounts. The thesis focuses on the Czech environment. Despite the fact that the analysis is based on photos, the context is also taken into account, i.e. the author of the...
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The influence of storage time on authentication of plant-based foods
Trödlerová, Martina ; Šislerová, Lucie (referee) ; Fialová, Lenka (advisor)
Fruit baby foods and purees belong among adulterated food, due to the prices of materials for their production. More expensive ingredients are replaced by cheaper, lower quality ones. This bachelor thesis deals with influence of storage time on the determination of samples authenticity The theoretical part of the thesis deals with the chemical composition of fruit (especially apples and peaches), production technology and methods of determining authenticity. In the experimental part, model samples were prepared and DNA was isolated from them. Then, using two different primer pairs, this DNA was amplified by real-time PCR and a specific product was detected by analyzing melting curves. On gel electrophoresis, it was possible to confirm the presence of these specific products. The last method was HPLC, where phenolic substances were analyzed.
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The effect of the dehydration method on the profile of volatile substances of selected fruits
Prystupa, Anna ; Trenzová, Kristina (referee) ; Vítová, Eva (advisor)
This bachelor's thesis focuses on the identification and quantification of volatile compounds in samples of selected tropical fruits, namely banana, kiwi, mango, pineapple, and pitahaya. The theoretical part provides a detailed description of the lyophilization method as a food preservation technique, its principles, and its applications in the food industry. The principles of conventional drying methods are also explained, along with a brief introduction to various types of drying equipment. Additionally, the characteristics of each tropical fruit species, including their chemical and aromatic composition, are presented. Lastly, the principle and instrumentation of solid-phase microextraction and gas chromatography-mass spectrometry are explained. The experimental part of the thesis focuses on the identification and quantification of volatile compounds in samples of fresh, lyophilized, and dried fruit. The results indicate that the chosen methods of preservation have varying effects on the profile of volatile compounds in different tropical fruit species. Losses of compounds or the formation of new compounds may occur, which lays the foundation for further research in this area.
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