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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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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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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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The use of aromatic herbs in the production of white sausages
Havlíková, Michaela ; Skoumalová, Petra (referee) ; Mikulíková, Renata (advisor)
The aim of the bachelor thesis is to compare the sensory properties of white sausages with the addition of different concentrations and types of herbs. Selected were basil, thyme and lavender. The aim was also to assess the microbial activity of selected herbs. The theoretical part describes the Czech legislation that controls the production and composition of sausages, the characteristics of raw materials that are used in the production of white sausages and the technological process of production. The theoretical part also deals with the theory of sensory analysis and microbiological determination of antimicrobial properties of used herbs. The experimental part describes the preparation of samples, sensory analysis and microbial test. In the sensory analysis, the evaluators assessed the different properties of the submitted samples by comparing only the concentrations of one herb. Next was a test performed to compare one concentration of all herbs against each other. Aqueous and organic herb extracts were prepared for the microbial test and the absorbance values on the microtiter plate were subsequently measured.
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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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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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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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Effect of roasting on the sensory profile of coffee
Šajdlerová, Kristýna ; Vítová, Eva (referee) ; Diviš, Pavel (advisor)
This bachelor thesis deals with the effect of roasting on the content of carbohydrates and aromatic compounds in coffee. It also studies changes in coffee acidity based on different level of roasting. In the practical part there was measured pH, it was conducted setting of glucose, fructose and sucrose content by liquid chromatography, analysis of aromatic compounds using gas chromatography and also sensoric analysis of 17 types of coffee. Each one was roasted using two different temperatures (210 °C and 240 °C). Based on the statistical processing of basic chemical analysis and sensory analysis, significant differences were found between determined parametres of coffee samples roasted at 210 ° C and 240 ° C. Processing of results of sensory and chemical analysis of coffee samples did not manage to differentiate coffee samples from each other based on their geographic origin. At a lower level of coffee roasting there was found weak, but statistically significant correlation between the results of the sensory analysis and the content of aromatic compounds, while for the higher degree of coffee roasting no correlation was found.
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Sensory evaluation of model non-chocolate sweets
Malyszová, Markéta ; Mikulíková, Renata (referee) ; Vítová, Eva (advisor)
The aim of this bachelor's thesis was to implement a sensory analysis of model non-chocolate sweets of a selected type – specifically gummy jellies. The theoretical part deals with the characteristics of non-chocolate confectionery, information about their composition and properties and technological processes of production. Principle of sensory evaluation, including selected methods of this analysis are mentioned, too. The experimental part focuses on sensory evaluation of prepared gummy jellies. Several samples were made, which contained the addition of herbal extract, namely chokeberry and echinacea. The samples were evaluated using a scale based on their colour, aroma, and flavour. Furthermore, a profile test of tastes was applied, and their overall acceptability was evaluated. Untrained assessors, students from Faculty of Chemistry BUT, performed the sensory evaluations. The aim was to assess the influence of these herbal extracts on the sensory quality of the sample. The pleasant colour and taste influenced the positive evaluation the most. On the other hand, the faint aroma and bitter taste contributed to the negative evaluation.
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Developement and characterization of protein food supplement from wheat bran
Zhahlou, Kim ; Punčochářová, Lenka (referee) ; Pořízka, Jaromír (advisor)
The bachelor thesis focuses on the development of a new, protein dietary supplement for athletes and followers of a healthy lifestyle. Nowadays, life is more intense the more he gave. From a physiological point of view, a person needs enough energy, which is provided by a varied diet composed of quality nutrients. In the experimental part, protein rods were made with the addition of lyophilized protein isolated from wheat bran. Wheat bran was selected as a suitable source of protein due to its availability, protein content from 14 % to 18 % and the relative simplicity of the protein isolation method. The protein bar thus produced does not contain any ingredient of animal origin, making it suitable for vegetarians and vegans. The textural properties of sticks with different amounts of plant material were compared by sensory analysis. For more illustrative results, the product was also compared with bars made by the same procedure, but with the addition of whey protein. With the addition of wheat lyophilisate over 5%, the negative effect on the evaluation of the textural and taste properties of the sticks was evaluated. Further studies could focus on optimizing the taste and addition of plant protein.
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