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Sensory evaluation of sweets
Boboková, Alexandra ; Burdějová, Lenka (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with a sensory analysis of a selected type of non-chocolate sweets – gummy jellies with sour coating. The theoretical part describes raw materials needed for the production of non-chocolate sweets, a list of non-chocolate sweets and their technological production are also mentioned. Sensory analysis and sensory evaluation methods are briefly described. The experimental part is focused on sensory analysis of selected yellow-coloured/lemon flavoured samples from five different producers. The samples were evaluated using a scale based on their appearance, colour, flavour, aroma and texture. Furthermore, the sensory profile and evaluation of aftertaste using time intensity methods were applied. Common consumers were represented by 20 untrained assessors from the Faculty of Chemistry of BUT. Bright colour contributed positively, while hard texture negatively to the overall evaluation of samples.
Sensory evaluation of drinks enriched with extracts of herbs
Scholzová, Kristýna ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with sensory evaluation of herbal non-alcoholic beverages, being a part of a new product development. The theoretical part provides information concerning chemical composition, health effects, food applications and aroma compounds of the herbs of interest (peppermint (Mentha piperita), sage (Salvia officinalis), St. John’s wort (Hypericum perforatum) and lemon balm (Melissa officinalis). Another topic is a description of sensory methods, requirements and arrangement of the analysis, statistical methods, and also technological processes leading to herbal syrups and beverages production. The practical part comprises sensory analysis of a few, newly designed, formulas of one-component and two-component alcohol free herbal beverages. The sensory panel consisted of 40 students of master's and also doctoral study programme at Faculty of chemistry, University of Technology Brno. Four subsequent experiments are introduced, each of them consisting of a few sensory tests and including corresponding sensory forms attached. The sensory tests arrangement was based on currently valid Czech Technical Standards, using a ranking, descriptive, paired comparison, sensory profile testing and scaling methods. For the purpose of statistical evaluation, Friedman, Kruskal-Wallis, PCA and Faktor analysis were used. Level of abilities and sensory experience of panelists were found comparable to consumer testing. The results include sensory characteristics of all of the beverages tested. In general, the one-component beverages were preferred to the two-component beverages and the additive colouring with aronia concentrate wasn´t found any benefitial, from the sensory point of view. The consumer questionnaire proved all of the samples to be very promising, but based on the sensory results, we would consider the mint and the sage-mint beverages being the most potentialy applicable samples.
Sensory quality of selected types of sweets
Michalíková, Veronika ; Hároniková, Andrea (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the sensory evaluation of selected types of non-chocolate sweets. In the theoretical part the production technology of non-chocolate sweets is described, including raw materials needed. Furthermore, basics of sensory analysis with characteristics of sensory evaluation and selected sensory methods are mentioned. The experimental part deals with the sensory evaluation itself; the selected sensory methods were applied on samples of gummy sweets. Four colours/flavours (strawberry, orange, lemon, apple) from five producers were chosen for evaluation, together 20 samples. The aim was to assess the differences in sensory quality of samples of the same type from different producers. Untrained assessors, from Faculty of Chemistry BUT, were invited for sensory evaluations. Significant differences were found among the samples, glossy appearance and pleasant characteristic taste contributed to the positive evaluation, on the contrary the rigid texture, bland taste and odour and possible off-flavour contributed to the negative evaluation.
Study of Factors Influencing Creation of Volatile Aroma Active Compounds in Natural Materials
Loupancová, Blanka ; Vávrová, Milada (referee) ; Kráčmar, Stanislav (referee) ; Fišera, Miroslav (advisor)
The production of high-quality foods requires the precise control of factors influencing their quality. The aim of this doctoral thesis was to monitor the influence of sterilization heating and storage time and temperature on selected parameters of model food matrix using suitable physical, chemical and sensory methods. Sterilized processed cheese was chosen as the model matrix. Processed cheeses are milk protein concentrates, produced by melting of mixture of natural cheeses, emulsifying salts, water and other dairy and/or non dairy ingredients. Desirable transformation of this mixture to homogenous, smooth, shiny mass with desired textural, structural, rheologic and sensory properties is caused by using high temperature (about 80-100 °C) during melting. Sterilized processed cheese is subjected to additional sterilization heating (above 100 °C) after production, significantly elongating its durability. The processed cheeses (dry matter 40 % w/w, fat in dry matter 45 % w/w) were analyzed in this work, the part of them was sterilized (117 °C 20 min). Cheeses were stored at various temperatures (cold 6 ± 2 °C, laboratory 23 ± 2 °C and elevated 40 ± 2 °C), sterilized cheeses for 2 years, non sterilized for 1 year. During storage, the samples for physical (instrumental measuring of colour and texture), chemical (assessment of fatty acids and aroma compounds) and sensory (paired preference test, ranking test and evaluation using scale) analyses were taken at regular intervals. The influence of sterilization heating and for another the influence of storage conditions on mentioned parameters were investigated. Non sterilized processed cheese kept their very good quality during all the declared durability (4 months), however, then the significant worsening of most sensory properties was observed. In consequence of sterilization heating the changes of cheese colour and texture were observed, confirmed by both sensory and instrumental assessment. The impairment of taste and aroma was also found. These changes are obvious immediately after production and differences were observed during all the durability. In the case of sterilized processed cheese, the significant impairment of single sensory properties was determined, the highest in the case of texture, taste and aroma. The results of instrumental techniques confirm conclusions from sensory evaluation. The measurements of colour and texture vindicate the formation of darker colour (increasing total difference of colour delta E*) and higher hardness (increasing Fmax) of sterilized processed cheeses, continuing during storage. The worsening of taste and aroma is in accordance with lower content of aroma active compounds and selected fatty acids.
Characterisation of processed cheese analogues
Chlebcová, Lenka ; Buňka, František (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the topic of cheese analogues, their characterization and qualitative and quantitative analysis of processed cheese analogues for determination the taste and aroma active compounds. The overall character of processed cheese analogues is theoretically compiled in the introductory part. Their utilization, causes of the production, market introduction, technological production process and microstructure, including their comparison with classical processed cheese are given here. Various kinds of fats were used for production of analyzed cheese analogues, therefore commonly used ingredients for their production, their physical-chemical and sensory properties have been described. Specifically butterfat, milk fat, coconut fat, palm fat and mixed oil. Samples used for the practical part of the diploma thesis were made at Tomas Bata University in Zlín. In the experimental part the profile of aroma compounds in individual cheese analogues samples was assessed by SPME-GC analysis. In total 34 compounds were identified. The results were evaluated and compared, with emphasis put on the influence of storage, different fats, different maturity of Edam cheese on the content of aroma active compounds and on overall sensory quality of the analogues.
Assessment of chosen aroma compounds in foods
Greifenthalová, Ivana ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This diploma thesis is focused on the problematic of assessment of 26 most important allergenic aroma compounds in foods, flavoured herbal teas were chosen as the model samples. Aroma is the one of the main characteristics of tea, which is closely linked to taste and odour. The theoretical part of this work is focused on the characteristics of tea, tea types, producing technology, classification according to the fermentation and also their undeniable impact on the human organism. In the experimental part, the allergenic aroma compounds in 10 chosen samples of flavoured tea were identified and quantified using the solid phase microextraction (SPME-GC-FID) in conjunction with gas chromatography. The work also includes sensory evaluation of taste and smell of tea samples by qualified assessors.
Characterisation of processed cheese analogues
Studýnková, Hana ; Buňka, František (referee) ; Vítová, Eva (advisor)
The aim of this diploma thesis was to identify and quantify the content of taste and aroma active compounds and to evaluate flavour of cheese analogue samples with various vegetable fats (coconut, palm, butter and mixed oils and butter) and differently matured Edam cheese using selected sensory methods. The samples were produced at Tomas Bata University in Zlín. Aroma compounds were extracted using SPME and assessed using gas chromatography. In total 43 compounds were identified, 14 alcohols, 9 aldehydes, 7 ketones, 8 acids, 5 esters and 1 terpene. Simultaneously the analogues were sensorially evaluated using scale, profile and ranking tests. The influence of storage time, type of fat and Edam cheese used on content of aroma compounds and sensory quality of analogues were evaluated. The cheese analogues with butter were sensorially evaluated as the best, with mixed oil as the worst. From the point of view of aroma compounds content, the significant differences between samples were evident. Using more matured Edam cheese, the content of aroma compounds declined, however, these samples were sensorially evaluated as better. The content of aroma compounds decreased also with storage time, which is more obvious in less matured Edam cheese. So all above mentioned factors influence the content of aroma compounds and thus the flavour of cheese analogues.
Characterisation of processed cheese analoques
Svítilová, Lenka ; Horváthová, Viera (referee) ; Buňka, František (advisor)
The aim of this diploma work is to characterise processed cheeses and their analogues, to identify and quantify aroma active substances in the samples of cheese analogues, to evaluate their flavour using selected sensory methods and to compare the acquired results with the flavour of corresponding classic cheeses. The theoretical part is focused on general characteristic, classification, production technology of the processed cheeses and their analogues and on the list of aroma active substances occurring in cheeses. Furthermore, the summary of the methods suitable for sensory and analytic evaluation of cheese flavour and for the isolation of aroma active substances is given here. The samples of cheese analogues were made in Tomas Bata University in Zlín from coconut fat, butter, palm fat, milk fat and sunflower-seed oil. The classic processed cheeses were acquired commercially in the chain-store Billa. The aromatic substances were isolated and quantified using SPME-GC method, the fibre with the polar stationary phase CARTM/PDMS was used. Overall, 44 aroma substances were assessed: 9 aldehydes, 17 alcohols, 3 esters, 10 ketones and 5 acids. Classic processed cheeses contained the largest amount of aroma substances, Edam cheese, used for the production of cheese analogues, the smallest. Aroma compounds found in cheese analogues were then compared with raw materials used (Edam cheese and various fats), with the analogues produced last year and with classic processed cheeses. Finally, the results of the SPME-GC method and the sensory analysis were compared. It is possible to state that there are noticeable extensive differences between classic processed cheeses and cheese analogues, especially in taste.
Sensorial and analytical evaluation of cheese analoques flavour
Brabcová, Lenka ; Horváthová,, Viera (referee) ; Vítová, Eva (advisor)
The aim of the diploma thesis was to determine the influence of different kinds of fats on the content of aromatic active compounds and total flavour of processed cheese analogues. Samples of the cheese were produced by Tomas Bata University in Zlín from concentrated milk fat, butter, palm fat, coconut fat and sunflower oil. The aromatic compounds were isolated from samples of fats and processed cheese analogues via HS-SPME-GC method. A fibre with polar stationary phase CAR/PDMS was used for capturing of aromatic active compounds. In different contents, total of 32 aromatic compounds were determined. The cheese from concentrated milk fat and butter had the highest content and cheese from sunflower oil had the lowest. For determination of acceptability and flavour, the cheese analogues were sensory evaluated at the same time. Ordinal test, evaluation via scale and profile test were used. Cheese made from concentrated milk fat and coconut fat were always evaluated as the best, cheese made from sunflower oil were evaluated as the worst. Finally results between SPME-GC and sensory analysis were compared. It was stated that the kind of fat used for production of processed cheese analogues significantly influences the content of aromatic compounds and thus influences flavour of the cheese analogues.
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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