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Lycium chinense and Lepidium meyenii in new food products
Novotný, Marek ; Vítová, Eva (referee) ; Vespalcová, Milena (advisor)
This diploma thesis deals with application of wolfberry (Lycium chinense) and maca (Lepidium meyenii) in food products. Both plants have high nutrition content and are studied for their health benefits to humans. In case of wolfberry it’s mainly immune-stimulating and antioxidant properties. Maca is known for increasing fertility and there’s also reported lowering of cholesterol and blood sugar. In theoretic part are summarized findings about chemical composition, science studies about effects of these plants, situation on the Czech trade and project of use. Aim of this thesis was to create practical demonstration of use and consumption both plants and to evaluate it by methods of sensory analysis. For this purpose three samples of wolfberry cereal bars and three samples of chocolate with maca powder were produced. These samples were sensory evaluated using ranking test, scale test and profile test. Higher amount of maca in chocolate had worse rating, while use of wolfberry was rated quite well. Therefore three wolfberry cereal bars were produced as the final product in cooperation with bakery and chocolate factory Fikar – bar with fruit filling glazed with chocolate, classical bar glazed and classical bar not glazed with chocolate, as a demonstration of possible industrial use.
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The effect of a storage conditions on aroma compounds in processed cheese
Štouračová, Anna ; Buňka, František (referee) ; Vítová, Eva (advisor)
The aim of this diploma thesis was to monitor influence of storage conditions (temperature and time) on content of aroma substances in sterilized processed cheeses and also on their flavour. The part of cheeses was stored at 6°C, second part at room temperature 23 °C and third part at 40 °C. Processed cheeses were produced by Madeta, a. s., sterilized at 117 °C 20 min. The analysis was made at regular intervals, cheeses stored 16 and 23 months were analysed in this work. The aroma compounds were isolated by SPME and subsequently identified and quantified by gas chromatography. In total 37 aroma compounds were identified and quantified, 7 aldehydes, 7 ketones, 6 acids, 12 alcohols and 5 esters. Total content of aroma compounds increases with higher storage temperature. The time of storage has also influence on content of aroma compounds, we may say, that content is increasing, although sharp growth was registered only after 23 months, namely in the thermostat. Simultaneously sensory analysis of cheeses was made. Ranking test and evaluation using scale were used. Cheeses from a fridge were always evaluated as the best in all categories. Cheeses stored at room temperature were evaluated worse and cheeses from thermostat were the worst. So it is apparent, that high temperature supports undesirable chemical changes in cheeses and certainly is related to their flavour.
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Influence of aroma active compounds on flavour of fruit yogurts
Malina, Lukáš ; Babák, Libor (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the determination of aroma compounds in fruit yoghurts. These compounds are crucial for flavour of these dairy products. Two types of fruit yoghurts were analyzed, creamy (8 % of fat) and light (less than 0,1 % of fat), with various fruit ingredients, produced in dairy Mlékárna Valašské Meziříčí, spol. s r.o. Analysis was carried out by gas chromatography with extraction of analytes by SPME - solid phase microextraction. Six groups of different aromatic compounds such as ketones, aldehydes, organic acids and their salts, alcohols and sulfides in different amounts were determined. These compounds have mostly microbiological origin (Streptococcus salivarius subsp. thermophilus, Lactobacillus delbrueckii subsp. bulgaricus are dairy yoghurt cultures usually used for yoghurt production), less amounts are present in cow's milk or in dairy additives. Yoghurts were simultaneously sensory evaluated using ranking test, scale test and pair test for determination of acceptability and flavour. The assessors were students and staffs faculty of chemistry VUT.
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Aromatic substances of wine
Stávková, Markéta ; Vespalcová, Milena (referee) ; Ruibar, Jiří (advisor)
This bacherols thesis consists of two parts, of theoretical part and practical part. The theoretical part delimits wine-producing regions in Czech republic, explains growing of grapevine. The thesis is concerned with the soil classification, amount of mineral element and decribes the quality and aroma of a wine. It´s briefly concerned with bouquet of wine during wine production. Deals with chemical changes in must during fermentation using yeast. The practical part is concerned with soil analysis of vineyard Rajhradské Klášterní. The goal of this experimental part was to finding out amout of mineral elements in samples and their comparison between the four vineyard. Aromatics are analyzed by gas chromatography and sensory analysis.
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The influence of thermal treatment on life of particular food products.
Žůrková, Pavla ; Ing.Gabriela Dereňová (referee) ; Ing.Petr Koflak (advisor)
This work deals with influence of heat processing on longevity of two selected products of the packing company Seliko trading a.s. For the research there were selected products Sterilised sauerkraut in sweet-sour pickle and Fatback spread. Evaluation has been done in laboratory premises of the packing company. There has been monitored mikrobiological stability after heat processing and sensory properties of the mentioned products always with an interval of one month. During the monitored seven months there appeared changes in taste and consistence of the products that are not defective in these products. The microbiological test taken after seven months was negative, just like at the beginning of the experiment. The result of the given findings is that the heat sterilisation was efficient and that during the storage there did not rise number of micro-organisms in the products.
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Assessment of aroma active compounds in unconventional fruit types
Krchňavá, Petra ; Divišová, Radka (referee) ; Vítová, Eva (advisor)
This bachelor’s thesis deals with the determination of aroma compounds in selected drinks produced from chokeberry (Aronia melanocarpa). The theoretical part is focused on the description of this plant, its chemical composition, properties, influence on the human body and possibility of utilization and processing. In the experimental part the aroma compounds in samples of sirup and liqueur from chokeberry were identified and quantified. . The aroma compounds were extracted by solid-phase microextraction and analysed by gas chromatography. A total of 43 compounds were identified. Concurrently, the sensory evaluation of samples was carried out. The profile test and evaluation using scales were used for evaluation of overall pleasantness and intensity of taste and odour. The contribution of selected descriptors (fruit, sweet, acid and other taste and odour) to overall sensory quality of samples was also judged.
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Sensory evaluation of coffee
Sýkora, Michal ; Omelková, Jiřina (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the sensory quality of chosen types of coffee. The theoretical part was focused on the production of coffee and raw materials needed and also an introduction to sensory analysis was described. The experimental part was focused on evaluation itself. Untrained assessors from Faculty of Chemistry BUT in Brno were invited for sensory evaluation, who evaluated selected coffee kinds using the preprepared form. Purchased samples were subjected to sensory evaluation by the ranking test and profile test. The intensity and/or pleasantness of seven selected descriptors (foaming, sweetness, acidity, astringency, bitterness, the foreign taste and odor) were evaluated using unstructured graphical scale with the verbal description of the anchor points. The results were then evaluated graphically and statistically processed.
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Sensory evaluation of cheeses
Pecinová, Ester ; Vránová, Dana (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the sensory evaluation of cheeses. The thesis focuses on Edam cheese and the selection of methods for its sensory analysis. In the theoretical part natural cheeses are characterised, their chemical composition, physical and chemical properties as well as their sensory properties are described, further they are classified from several points of view and also individual steps of manufacturing process of Edam cheese are described. After that the literature search was made focused on sensory evaluation, within the methods were chosen for the experimental part, specifically measuring of overall preference and liking/disliking, appearance, colour, texture, aroma and flavour ratings using the hedonic scale and rating of chosen flavour descriptors by the profile method. In the experimental part the selected sensory methods were applied on 3 samples of Edam cheese, manufactured in 3 different modes of heat treatment of milk. Two sensory panels were involved in the evaluation: consumers and experts. Cheese from the first production (65 °C 30 min) was evaluated as the most acceptable; on the contrary cheese from the second production (80 °C 30 s) was evaluated as the least acceptable.
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Chemical and sensory analysis of fruit juice from selected cultivars of European elder
Ješková, Kristýna ; Vespalcová, Milena (referee) ; Hrstka, Miroslav (advisor)
The aim of this thesis is the chemical and sensory analysis of the juice from fruits of cultivated varieties of elderberry (Sambucus nigra L.). In the theoretical part botanical description of elderberry including its distribution and places of existence are given. There are also mentioned medical effects and collection of various parts of the elderberry as well as breeding certain species and methods evaluating sensory features of the juice samples prepared from the cultivated varieties of elderberry. In the experimental part some chemical parameters (yield, soluble dry matter content, relative density, pH, titratable acidity, formol number, reducing saccharides) in the juice of berries of eighteen cultivated varieties of elderberry were determined. In fifteen cultivated varieties was made sensory evaluation using profile test and scale. The aim of the evaluators in the evaluation using scale was to evaluate the taste, smell, sensory quality and preferences according to seven point cathegorical hedonic scale. In the profile test, five point scale was used to evaluate the intensity of chosen flavours: acidic, sweet, bitter and others. Overall impression of the sensory evaluation was rather not positive. In majority of the samples the taste and smell were evaluated as good or satisfactory and their general acceptability, too. The juice from the wild elderberry was estimated as worse than in other samples, its taste, smell and overall acceptability were unsatisfactory. In majority of the cultivated varieties were the taste and smell estimated as unsatisfactory as well as their general acceptability.
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Sensory quality of fruit juices
Hamalová, Veronika ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This Bachelor‘s thesis deals with the evaluation of sensory quality of orange juice from different producers. All selected samples were made from concentrate. In total five samples bought in Tesco Stores CZ in Brno were evaluated The theoretical part focuses on the composition and properties of orange and orange juice, and their production technology. The selected methods for sensory evaluation of foods are mentioned. The definition of orange juice according to Czech Standard 56 8541 is also presented in this part. The appearance, color, taste, smell and consistency were evaluated using ordinal scales, taste development using graphic scale. The ranking test was also included. Written results were graphically evaluated and statistically treated.
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