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Aroma profile of selected types of fruit juices
Baštová, Daniela ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This diploma thesis is focused on determination the aroma profile of selected species of fruit juices (apple, grape, carrot, orange, blackcurrant and elderberry juice). The theoretical part deals with the composition and properties of selected species of fruits and their juices, then deals with juice‘s technological process and selected methods for the determination of aroma active compounds. The experimental part describes the instrumental and sensory analysis. The six pure fruit juices and five mixed fruit juices were used for instrumental evaluation. The aroma active compounds were extracted by SPME and subsequently identified and quantified by gas chromatography. The sensory evaluation was performed by ranking test and evaluation using hedonic scale.
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Assessment of aroma active compounds in elderberries
Kolibačová, Silvie ; Ürgeová,, Eva (referee) ; Vítová, Eva (advisor)
The aim of this diploma thesis was to determine the aroma active compounds in different varieties of black elderberry (Sambucus nigra L.) and in elder juices that were mixed in different proportions with grape juice. The sensory analysis of these juices was subsequently performed with focusing on their tastiness. The theoretical part deals with the description of the black elderberry, its occurrence, composition and use at home and in industrial processing, as well as a description of aroma active compounds, which have been previously identified in elder by various authors. In the experimental part aroma active substances were identified and quantified in seven selected varieties of elder. Solid Phase Microextraction method was used for their isolation and subsequent analysis was performed by gas chromatography. 39 aroma active compounds were identified totally in fruits of the black elderberry, of which 15 alcohols, 11 aldehydes, 7 ketones, 5 esters and 1 acid. 45 aroma active compounds were identified totally in elderberry juices, of which 19 alcohols, 8 aldehydes, 5 ketones, 7 esters and 6 acids. The sensory analysis of elder juices was performed using ranking test and evaluation using the scales.
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Preparation and characterization of alcohol-free beers with different flavour
Benešová, Pavla ; Vávrová, Milada (referee) ; Márová, Ivana (advisor)
This diploma thesis deals with preparation and characterization of alcohol-free beers with different flavours. Five flavoured and four pure, commercially available beers were tested. Three alcohol-free beers were then selected and used for preparation of flavoured beers. Ingredients used for production of flavour were honey, raspberry, ginger and cranberry. Analysis was focused mainly on substances of phenolic nature. Flavoured beers were also tested in sensory analysis. Ingredients used for flavouring of beers and production of both alcoholic and alcohol-free beers are described in theoretical part of the thesis. Analysis of polyphenols, flavonoids, technological characteristics and anthocyanins was performed using spectrophotometric method. Phenolic substances were identified and quantified by HPLC/PDA. Ascorbic acid was analysed by HPLC-NH2/UV. Results proved an increase of polyphenols, ascorbic acid and anthocyanins during flavouring of alcohol-free beers in dependence of used ingredients. Sensory analysis showed that as the best rated was the Staropramen beer with raspberry flavour. On the contrary, flavoured Bernard beers were poorly rated.
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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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Application of profile test on several types of foods
Přerovská, Mariya ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This diploma thesis was focused on the use of profile tests for sensory analysis of foods. The development of profile methods, advantages and disadvantages of the techniques, specific training of panelists, the organization and the requirements for testing place and testing is described in theoretical part. There is a brief overview of other methods and legislation used in sensory analysis. In the experimental part of this work several types of foods such as bread, ham, yogurt, apple and chocolate have been selected. For each of these foods the forms for profile evaluation of flavor and texture have been developed. Consequently, the selected samples were sensorially evaluated by panel composed from students of FCH BUT.
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Influence of aroma active compounds on flavour of fermented dairy products
Tvrdková, Denisa ; Pšenáková, Ivana (referee) ; Vítová, Eva (advisor)
The theme of this thesis is to determine the aroma active compounds in fermented dairy products. These substances significantly influence the palatability of these dairy products. Five kinds of dairy products were analyzed. Two types of creamy yogurts, and three types of yoghurt milks were produced at the dairy Ekomilk Ltd. in Frydek - Mistek and four types of acidified milk, five kinds of creamy yogurts, two kefir milks and two clabbered milks come from production of the company Kunin, Inc. Ostrava - Martinov. The SPME extraction method was used for the determination of aromatics, subsequent analysis was performed using gas chromatography. Compounds contained in fermented milk products were identified and quantified on the basis of the measured standards. Total 39 compounds, including 16 alcohols, 7 acids, 6 aldehydes, 6 ketones and 4 esters were identified. Fermented dairy products were twice subjected to sensory evaluation by the ranking test and scale test. The assessors were chosen from students, postgraduate students and staff of faculty of chemistry BUT. Consumers evaluated very positively yogurts, yogurt drinks and acidified milks, while kefir milks and clabbered milks did not suit in some aspects.
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Influence of aroma active compounds on flavour of yogurts
Malina, Jiří ; Babák, Libor (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the questions of determination of aroma active compounds present in yoghurts. These compounds are crucial for flavour of these fermented dairy products. Four types of yoghurts were analyzed, creamy (10 % of fat), medium-fat and medium-fat Bio (3 % of fat) and light (0,1 % of fat), produced by Mlékárna Valašské Meziříčí, spol. s r.o. Analysis was carried out by gas chromatography with extraction of analytes by SPME - solid phase microextraction. Five groups of different aroma active compounds such as ketones, aldehydes, organic acids and their esters and alcohols in different amounts were determined. These compounds are mostly metabolic products of Streptococcus salivarius subsp. thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, dairy yoghurt cultures usually used for yoghurt production. Less amounts are present in cow's milk or in dairy additives. Yoghurts were simultaneously sensorially evaluated using ranking test and scale test for determination of acceptability and flavour. The assessors were students and staffs of faculty of chemistry BUT.
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Testing of sensory abilities of assessors - studying of taste sensitivity
Chytilová, Eliška ; Janoušková, Eva (referee) ; Vítová, Eva (advisor)
The aim of this diploma thesis is to study the sensitivity of one of the five human senses - taste. It deals with anatomy of taste sense, taste perception and it also describes which kinds of taste we are able to identify. Sensory analysis is focused on human senses and their practical use. Consequently, the requirements for sensory assessors, requirements for sensory laboratory, methods used in sensory analysis and summary of legislation in this area are described in this thesis. In order to perform qualified sensory assessment, the laboratory needs accreditation. On this account the requirements of Czech accreditation institute are mentioned here. Methods suitable for studying of taste sensitivity of sensory assessors are chosen and validated in experimental part. Standard operating procedures are elaborated for these chosen methods.
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Testing of sensory abilities of assessors: studying of smell and vision sensitivity
Hýsková, Eva ; Janoušková, Eva (referee) ; Vítová, Eva (advisor)
This diploma thesis was focused on visual and olfactory senses and their role in the sensory evaluation. The requirements for assessors working in sensory analysis, for testing place and requirements of the Czech Institute for Accreditation for the accreditation of laboratories working in the field of sensory testing are summarized here. An overview of methods and legislation in the field of sensory analysis is also presented. Methods for studying of smell and vision sensitivity of assessors were selected in the experimental part of this thesis. The methods were verified in the sensory laboratory, validated and standard operating procedures have been developed to the individual methods.
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