|
|
Qualitative parameters of selected foods in the gluten-free diet
Jiříková, Eva ; Doležal, Marek (advisor) ; Pánek, Jan (referee)
The gluten contained in some cereals plays an important role in the quality of bakery products. However, it is also associated with a range of diseases which require a gluten-free diet. In the first part of the work there is a brief overview of the knowledge on the given topics. The aim of this work was to compare qualitative parameters of selected foods (long-life bakery products) for gluten-free diet. The work included 31 different long-life bakery products (biscuits, wafers, sponge biscuits, extruded products, cracker products) from various producers (including 8 gluten products). The information on the product labels indicates that the food is energy-rich (1640-2310 kJ). Carbohydrates accounted for the largest share of 2/3 of products (48.3-77.8%), of which sugars accounted for more than 10% of the energy value. The remaining 1/3 of the products were rich in fats (49.2-66.8%). The energy content of protein was low (<13%) in all products. After extraction of fat and conversion of fatty acids to methyl esters, the fatty acid composition was determined by gas chromatography (GC-FID). Predominantly represented were monounsaturated fatty acids (MUFA) with 16.1-83.6%, and polyunsaturated fatty acids (PUFA), with 0,6-25,4%. Three samples exceeded, in 100 g of product, the saturated fatty acid intake (SFA)...
|
|
|
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.
|
|
|
Comparison of aroma profile of selected types of sweets
Polochová, Petra ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This diploma thesis focuses on identification of aroma active substances and sensory analysis in samples of non-chocolate sweets. For experimental part jelly candies were chosen as model samples. Specifically gummy bears with strawberry, lemon, apple and orange flavour were used. The theoretical part deals with the legislation and technology of manufacturing non-chocolate sweets, characterization of aroma compounds including those which could be allergenic. Furthermore this thesis describes a method of their determination using solid phase microextraction and gas chromatography with mass spectrometry. The end of the theoretical part is dedicated to methods of sensory analysis that were used. In the experimental part, the chosen method HS-SPME-GC-MS was used to identify volatile aroma active substances in selected samples of jelly sweets. The substances that are potentially allergenic were also quantified. For the evaluation of sensory quality scales, profile test and overall acceptability were used. The single samples differ in number and type of volatile compounds depending on producer and flavour. Altogether 119 compounds were identified including 12 allergenic.
|
|
|
Verifying of the method for assessment of allergenic aroma compounds in sweets
Maňáková, Adriena ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
This thesis deals with the assessment of aroma active compounds in non-chocolate confectionery and their influence on sensory quality. In the theoretical part the production technology of non-chocolate confectionery from raw materials to final product is described. Furthermore, aroma active substances, including those potentially allergenic, are characterized, and the method for their determination by solid phase microextraction and gas chromatography with mass spectrometry is briefly described. Sensory analysis and sensory evalutation methods are briefly desribed. Within expermental part of the work selected parametres of the HS-SPME-GC-MS method were optimized, aroma compounds in samples of hard candies were identified, and 24 potentially allergenic aroma substances were identified and quantified. Finally, a sensory analysis of these samples was performed. Differences in the number and type of volatile compounds were found between the samples. Overall 393 compounds were indetified including 19 allergens.
|
|
|
Senzorické hodnocení vybraných druhů ovocných vín
PRÁŠEK, Jiří
The aim of this thesis was to prepare at least three samples of fruit wines and make a sensory evaluation of them within a group of evaluators. The results of the sensory evaluation of fruit wines bought in the market were added. The sensory analysis of the fruit wine samples was done at the Faculty of Agriculture at the University of South Bohemia in České Budějovice. Evaluators (n= 61; 21 to 55 years old) made a perception (ranking and sensory profile) of the fruit wine samples. The best self-made fruit wine was rosehip wine (fruit of Rosa canina). The worst self-made fruit wine was blackthorn wine (fruit of Prunus spinosa L.). The assessors did not register any big differences during the analysis of the commercially made fruit wines, therefore the variability in evaluation depended on the individual preferences. The complete impression of evaluated fruit wines mainly consisted of the results from analysis of the aroma and the taste of those samples.
|
|
|
Quality of poultry meat in relation to the production method
KADLECOVÁ, Lucie
The topic of this thesis is the quality of poultry meat in relation to the production method. In the literature review, poultry meat is described, then its consumption in the Czech Republic and its chemical composition. Selected methods of sensory analysis are also described. Types of tested meats are characterized in the practical part. This thesis is also focused on the experimental evaluation of the chemical composition of chicken breast muscle from the Loužná farm using the NIR method and comparing the composition changes depending on the age of the chickens. It is followed by selected sensory methods aimed at recognizing differences in chicken meat from three different productions. In addition, there was published a questionnaire to determine citizen's preferences for products (chicken meat) from different production methods.
|
|
|
Quality assessment of gluten-free foods with a focus on pastries
ZIMMELOVÁ, Helena
The topic of this thesis is the production of gluten-free bread from naturally gluten-free flour, which will be enriched with suitable additives that will increase antioxidant activity and naturally effect on the structure of the pastry, so it will meet the sensory requirements of final consumers. The literary part define, which proteins can be found in cereals, what does the gluten means, its function in the pastry and which diseases can cause. In connection with these diseases, a gluten-free diet for improving the patient's health and suitable foodstuff are briefly described. The literary part is concluded with the theory of sensory evaluation. The practical part deals with the production of naturally gluten-free breads enriched with ingredients from kitchen onions (Allium cepa L.) and subsequent sensory evaluation of this bread. Selected statistical procedures were used to obtain, processed and evaluated data. Antioxidant activity was also monitored and evaluated. By using texture-meter was find out, what effect has additives on aging of gluten-free bread.
|
|
|
Senzorické hodnocení vybraných obilných nápojů
URBAN, Martin
The aim of this diploma thesis was a sensory and nutritional evaluation of vegetable drinks. The analysis focused on rice and oat drink. Part of the population has health problems with milk consumption. Some substitutes can be beverages from legumes, cereals, nuts, etc. Oat and rice drinks does not contain cholesterol, are a source of minerals and vitamins. Rice and oat drink does not contain lactose or milk proteins. The downside is the insufficient amount of protein and the fact that, unlike milk protein, the protein of cereals is poor, deficient. Rice drink does not contain gluten. The sensory analysis aimed to compare individual drinks and determine their differences between samples, to determine the intensity of certain properties and to rank the samples from best to worst. The sensory analysis confirmed the differences between manufacturers. In the case of rice beverages, the evaluators concluded that they perceived the difference between the product of Alpro and Alnatura, with the Alnatura drink being considered the most acceptable. The amount of fat in rice beverages was low (1-1.1 g fat per 100 ml). Drinks also contain little protein (0.1-0.3 g / 100 ml). Oat beverages differed in particular with Alnatura and Delhaize - Bio. The evaluators preferred Delhaize Drink Company - Bio the most. The nutritional composition of the fat-like products is similar to rice beverages (1-1.5 g fat per 100 ml). The amount of protein was slightly higher (0.6-1 g protein per 100 ml). From a nutritional point of view, there is a noticeable difference between cow's milk and oat and rice beverages. The rice and oat drinks that were preferred contained the most sugar and the brewing flavor was the least noticeable.
|
|
|
Complex characterisation of medical herbs and study of their utilization in food industry as a source of functional components
Burdějová, Lenka ; Kráčmar, Stanislav (referee) ; Šilhár, Stanislav (referee) ; Polovka, Martin (advisor)
Presented thesis deals with the complex characterization of extracts from medical plants using spectroscopic and chromatographic techniques, with emphasis on the influence of solvent, post-harvest treatment of the sample, location and year of production on selected parameters. Part of the work is devoted to application of selected extracts from medical plants in suitable form into beverages. The thesis is divided into two parts. At the first part of the work combination of electron paramagnetic resonance, ultraviolet visible spectroscopy, liquid chromatography and inductively coupled plasma optical emission spectrometry was applied for characterization of aqueous, ethanol and dimethylsulfoxide extracts from 10 selected medical plants, which were collected from two different locations during two years (2015, 2016) and post-harvestly treated by two ways (freezing, drying). In total, 39 parameters were determinated: namely total phenolic compounds content, total flavonoids content, 14 specific phenolic compounds, colour characteristics in the CIE L*a*b* system (L *, a*, b *, C*, h°, BI), radical-quenching activity using the cation radical of the 2,2'-azino-bis- (3-ethylbenzothiazoline-6-sulfonic acid), antioxidant/pro-oxidant activity using the spin trapping technique in the presence of 5,5-dimethyl-1-pyrrolin-N-oxide (DMPO)/potassium peroxodisulphate and content of 15 minerals (Al, As, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, P, Pb, Zn). The results confirmed that the studied parameters of medical plants are influenced by the extraction system, post-harvest treatment of samples, year of production, origin of samples (locality) and species composition. It has been shown that the type of extraction solvent significantly affects the composition of the extracts. On the basis of these analyzes, for food application – the isolation of the main functional components (phenolic compounds, flavonoids) –50% ethanol, post harvest treatment by drying and samples of Mentha piperita, Melissa officinalis, Hypericum perforatum and Salvia officinalis were selected. The second part of the thesis was focused on the application of selected extracts of medical plants to beverages (syrups). The above mentioned plants, 25% ethanol instead of 50% ethanol (due to the limitation of the ethanol content in final raw material), were selected for the application. At first, extraction of medical plants was optimized. Suitable ratio of material and solvent (1:10), extraction time (8 h) and herb absorbency (50–62 %) were determined. The prepared extract after filtration was applied to the syrup concentrate in different ratios to produce one-species syrups and further sensorially tested to select the suitable recipe, the best flavour and basis for the production of two-species syrups. The mint syrup was the most tasty and generally the most acceptable one-species syrup, and sage syrup was selected as the basis for two-species syrups. Further, the most appropriate recipes of the two-species syrups were chosen, the most sensorially acceptable one was selected and further tested if it would be appropriate to colour them. Preferentially, it has been found that it is not necessary to colour two-species syrups. On the basis of the sensory analysis, it has been found that peppermint and sage-peppermint syrups were the most tasty and acceptable syrups, which could be, after further testing, produced industrially to enrich the food market.
|
|
|
Využití náhradních sladidel v nealkoholických nápojích a jejich vliv na senzorickou jakost
TOLKNEROVÁ, Denisa
The subject of this thesis was to evaluate the use of sweeteners in a selected group of soft drinks from the viewpoint of the sensory quality. Using selected methods of sensory analysis were evaluated four samples of soft drinks with lemon flavor. The first sample A - Sprite contained aspartame, acesulfame K and fructose - glucose syrup. The second sample B - Slice consisted of the aspartame and acesulfame Ksweeteners. Sample C - Lemon contained only sugar and last sample D - Santerre, was composed of aspartame, acesulfame K and sodium saccharin. The evaluators were divided into two groups according to age. The first group of respondents was composed of students from the University of South Bohemia in the age of 18-27 years. The second group was composed of randomly selected people aged 40+. The aim of the thesis was to determine whether there is a disparity between the groups. Top rated sample became the sample A - Sprite. Differences occurred in sample B and C. Sample B which contains aspartame and acesulfame K was preferably evaluated bythe first group, whereas the second group consisting of older respondents evaluated preferably sample C Lemon. Lemon sample contains only sugar and its taste is therefore less noticeable or even perceived as without flavour, based on the evaluated results.The lowest rated sample was unambiguously sample D, which contains sweetener aspartame, acesulfame K and sodium saccharin. Part of this work was a questionnaire for consumers.Its main aim was to find out what mostly influences respondents when buying soft drinks, what attitude artificial sweeteners they have and if they find the composition of soft drinks determinative.
|
guest ::
