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Použití nasycených vyšších mastných kyselin v technologii vína
Chvalinová, Klára
Sulfur dioxide has been used in the wine industry for many centuries due to its antimicrobial and antioxidant effects. However, the problem is that SO2 is a major allergen and when consuming higher doses, health complications (such as headaches, stomach aches, asthmatic problems) may occur. It is therefore important to find a suitable substitute, or rather a supplement to this substance. One of the options is the use of saturated higher fatty acids (HFA). These substances naturally occur in nature and a small amount of them is formed by yeasts themselves during fermentation. Thanks to HFA the yeast cells´ lipid membranes are changed (their liquidity), resulting in cell degradation, slowing of metabolism and thus slowing down the fermentation until it is stopped. In this experiment, a mixture of HFA, octanoic, decanoic and dodecanoic acid, ratio 2:7:1, respectively, was used at doses of 5, 10, 20, 30, 40 and 60 mg/l, with two variants of the application SO2, 20 mg/l or 40 mg/l. The HFA residues, the corresponding ethyl esters and the influence on sensory properties of the wine were observed. The results of this experiment show (or HFA residues) that the more HFA is added, the more they are absorbed by the yeasts. At the same time there was a very slow esterification in time and thus a low influence on the aroma of wine. Sensory analysis showed the HFA dose of 20 mg/l as the limit from which we are able to recognize differences in HFA doses. There was also an influence of sludge particles. The longer the wine matures, the less sludge particles it contains, hence the HFA are bound on the yeast cells, and thereby their influence on wine sensory is reduced.
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Kvalitativní parametry vybraných sirupů v maloobchodní síti
Červinková, Veronika
This thesis was prepared at the Institute of Post-Harvest Technologies of Horticulture at the Faculty of Horticulture of the Mendel University in Brno in years 2016/2017. The aim of the thesis is to determine qualitative parameters of syrups in retail shops. The thesis contains technological processing and quality requirements for syrups. The practical part deals with the evaluation of selected parameters. The syrup of the YO brand, which showed the highest antioxidant capacity and all polyphenols, was evaluated as the best. The worst parameters were Neli's syrup, which did not contain any fruit component.
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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)...
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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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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.
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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.
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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.
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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.
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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.
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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.
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