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Possibilities of processing the fruit of lesser-known fruit tree species
Vachta, Jonáš ; Hudečková, Helena (referee) ; Mikulíková, Renata (advisor)
This diploma thesis deals with the possibilities of using the fruits of common quince (Cydonia oblonga), common medlar (Mespillus germanica) and flowering quince (Chaenomeles speciosa) for food purposes, specifically for the production of jellies and jams. The goal was to create a product that would capture the character of the fruit used, preserve its beneficial properties, such as aromas and the content of bioactive substances, and at the same time be pleasant for consumers. A total of three types of products were prepared, namely gelatin jelly, agar jelly and jam for each type of fruit used. The product samples were subjected to sensory analyses, the aim of which was to determine the optimal addition of sugar to the product, to determine the overall consumer acceptability of the individual samples, and in the case of jelly, also to compare the sensory properties of the gelatin and agar variants. For chemical analyses, model samples were prepared, the composition corresponding to the best sensorially evaluated samples from each type of product. The total content of polyphenols, the total content of flavonoids, the content of vitamin C, the content of lipophilic pigments, ubiquinone and phytosterols and the profile of volatile compounds in individual samples were studied. The analysis results showed that the jams, as heat-processed products, generally retained a greater amount of bioactive substances compared to the jelly samples, and in certain cases even a greater amount than the fruit samples. The jelly samples, on the other hand, retained a greater amount of the original fruit aroma.
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Evaluation of coffee and coffee substitute beverages from the perspective of sensory and antioxidant properties
HONYSZOVÁ, Tereza
The aim of the thesis was to evaluate selected coffee and coffee substitutes in terms of sensory properties and chemical properties with a focus on antioxidant properties and polyphenolic substances. The thesis was divided into two parts. The first, theoretical part, deals with the cultivation and processing of coffee, consumption of coffee and coffee substitutes, legislative definition of this issue. It also characterizes the most important chemical substances in coffee. The second, practical part, deals with the sensory analysis of selected coffee and coffee substitutes samples. The physical and chemical properties of the selected samples were determined. Subsequently, the antioxidant activity of the samples and the total polyphenol content were determined. Statistical analysis evaluated differences between the samples and correlation analysis was performed. The last part of the thesis was a questionnaire that focused on the consumption of coffee and coffee substitutes. Statistically significant differences were found for six of ten descriptors when evaluating sensory attributes of the samples. The samples differed significantly also in the physicochemical analyses. The Standard coffee sample had the highest pH value, and among the coffee substitutes it was the Organic Hemp coffee. The coffee samples had higher soluble solids than the coffee substitutes samples. When colour was measured, the coffee samples were found to be darker than the coffee substitutes. From the measurements of antioxidant activity and polyphenol content, the sample of the coffee substitute Red espresso was evaluated as the best.
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Use of citrus fruits in the food industry
Havlíková, Michaela ; Hudečková, Helena (referee) ; Mikulíková, Renata (advisor)
The main objective of the thesis was to prepare marmalades, jellies, and dried slices of citrus fruits. Three types of citrus fruits: orange, grapefruit, and pomelo, were chosen for this thesis. The nutritional characteristics of the prepared products were determined including volatile matter content, dry matter content, pigment content, lipophilic content, and vitamin C content. The aforementioned products were also subjected to sensory analysis to assess their taste, aroma, texture, colour, and overall acceptability. The theoretical part describes the legislation dealing with citrus processing, marmalades, dried fruit and jelly confectionery. Further, the characteristics of the aforementioned food products and the characteristics of citrus fruits are also given. The theoretical part also deals with the theory of the methods used, i.e. sensory analysis, gas chromatography with mass spectrometry, and high-performance liquid chromatography. The experimental part describes the preparation of samples and the performance of individual determinations. In the sensory analysis, marmalades, jellies, and dried sheets were evaluated separately. The evaluators assessed their acceptability depending on the citrus used. The volatile substances were also determined by gas chromatography-mass spectrometry. The moisture and dry matter of the products were determined by drying and the pigments and lipophilic substances contained in the products were determined by high-performance liquid chromatography.
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Possibilities of using rose hips in the food industry
Maráčková, Adéla ; Kovalčík, Adriána (referee) ; Mikulíková, Renata (advisor)
This thesis focuses on the possibilities of using rose hips in the food industry. The aim of this thesis was to design and create sensory acceptable food products which are made from rose hips. A recipe was created for rosehip jams, chutneys and jellies. During the development of the recipe, individual flavors of rosehip products were evaluated. Freshly ground spices combined with fruits and vegetables were used to flavor the products. According to the optimized recipe for chutney, 1 standard and 3 types with spices were produced: chili, allspice and ginger. A recipe for jams was also prepared - 1 standard and 3 types: cardamom, cinnamon and rosehip jam in combination with apple jam in a ratio of 1:1. Finally, a jelly recipe was created - 1 standard and 3 types with spices: cinnamon, allspice and anise. Individual rosehip products were subjected to sensory analysis and their organoleptic properties were evaluated. The sensory analysis was divided into three parts – for jellies, jams and chutneys. The best rated was a sample of rosehip jelly without the addition of spices. Among the jams, the best rated sample was the jam with the addition of cardamom, which was popular with the respondents because of its pleasant and non-traditional taste. For rosehip chutney, the sample without the addition of spices was the best rated. The mass spectrometry method was used to determine the presence of ionones in the samples, the presence of which is typical for rose hips. The presence and concentration of vitamin C, lipophilic substances and total pigments were determined in the respective rosehip products using the high-performance liquid chromatography method. It was verified by the method of high-performance liquid chromatography that a considerable amount of vitamins was preserved even after the preparation of the resulting products, which were heated. The results of the work pointed to the potential of rosehips, which can be used in the food industry.
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Jelly candies with the addition of bilberry (Vaccinium myrtillus) extract
Knapovská, Pavlína ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
This thesis deals with the application of bilberry fruits (Vaccinium myrtillus) and their extract to jelly candies and the subsequent characterization of these candies in terms of volatile compounds, total phenolic compounds and anthocyanins, antioxidant activity and sensory quality. The volatiles were determined by headspace solid-phase microextraction coupled to gas chromatography with mass spectrometry and standard spectrophotometric methods were used for the determination of bioactive compounds. Total phenolic content was determined by the Folin-Ciocalteu method, antioxidant activity by the TEAC method and total anthocyanin content by pH differential analysis. The sensory quality of the samples was evaluated using unstructured graphical scales. The preparation of the bilberry extract was optimized on the basis of total phenolic content and the following conditions were selected as the optimal: a weight of 1000 grams of bilberries per litre of water, a temperature of 50 °C, and an extraction time of 2 hours. The optimum additions to candies were selected, by sensory analysis, as 25 wt. % of extract and 15 wt. % of bilberries. A total of 45 volatile compounds were identified in the candy with bilberry extract, the most abundant being (E)-9-hexadecen-1-ol (22,7 %), furfural (10,9 %) and 2-ethylhexan-1-ol (10,0 %). The total phenolic content was 1141 ± 11 gGAE · g-1, the antioxidant activity was 660 ± 66 gTE · g-1 and the total anthocyanin content was 418 ± 23 gC3G · g-1. A total of 40 volatile compounds were identified in the candy with bilberry and the most abundant were linalool (22,7 %), (E)-9-hexadecene-1-ol (16,1 %) and 2-ethylhexan-1-ol (8,4 %). The total phenolic content was 1735 ± 56 gGAE · g-1, the antioxidant activity was 1109 ± 32 gTE · g-1 and the total anthocyanin content was 745 ± 23 gC3G · g-1. With the addition of both the extract and the bilberries, the candies showed a significant increase in bioactive and volatile compounds content, and the colour and flavour of the enriched samples were positively evaluated, thus improving their overall acceptability.
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Classic vs. bulgarian yogurt - sensory quality vs. chemical and microbiological composition
Podloučková, Michaela ; Němcová, Andrea (referee) ; Vítová, Eva (advisor)
This thesis compares classic and Bulgarian yoghurt in terms of volatile content, sensory quality, and microbial profile. The volatiles were identified and semi-quantified by gas chromatography with mass detection in conjunction with solid phase microextraction, whereas classical culture followed by real-time polymerase chain reaction (PCR) was used to determine the microbial profile. Sensory analysis consisted of evaluation by graphic scales, profile and ordinal tests. In the experimental part, 3 samples were produced, a "classic" white and Bulgarian yoghurt made from commercial yoghurt cultures, and a traditional Bulgarian yoghurt imported directly from Bulgaria. Based on the PCR analysis performed, bacterial DNA was confirmed in all yogurts, only the traditional Bulgarian yogurt also contained yeast DNA. The Bulgarian traditional yoghurt thus differed in its detectable yeast taste, but above all in the qualitative and quantitative composition of the volatile substances. Of the 29 compounds identified, 20 were present in this yoghurt; esters were the main group, while ketones predominated in the other yoghurts. From a sensory point of view, the Bulgarian yoghurt made from commercial culture was the best evaluated, with a pleasant appearance, a pleasant smell and a pleasantly sour taste and an overall excellent sensory quality.
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Influence of storage on the microbial composition of French Saint-nectaire cheese
Šislerová, Lucie ; Mikulíková, Renata (referee) ; Brázda, Václav (advisor)
The aim of my work is the comparison of microbial composition between farmtype and dairytype of Saint-nectaire cheese and the influence of storage time and temperature on the development of microbial composition, content of fatty acids and aromatic substances. Selected microorganisms were identified by RT-PCR. In addition, Penicillium roqueforti and fuscoglaucum have been identified in the Saint-nectaire farm type compared to the dairy type. In both types of cheese, the highest amount of selected microorganisms was detected in fresh cheese. When stored at 20 °C, an increase over fresh cheese occurred in the following microorganisms: Streptococcus thermophilus, Lactobacillus bulgaricus, Cladosporium herbarum and Penicillium commune and camemberti, and the presence of contaminants and pathogens was noted. After one week of storage at 20 °C, they were Micrococcus luteus, Salmonella enterica and Staphylococcus aureus, and after another two weeks of storage, Listeria monocytogenes was identified. The fatty acid and volatile compounds were compared for five samples: fresh cheese, cheese stored in the refrigerator for one week and three weeks and cheese stored at 20 °C for one week and three weeks. The content of bound and free fatty acids was measured, both by GC-FID. The content of bound fatty acids was comparable in all measured samples. The highest content of free fatty acids was in the cheese after three weeks of storage at 20 °C. The most common fatty acid is palmitic acid. Volatiles were determined by HS-SPME-GC-MS. The most volatiles were identified in the cheese after three weeks at 20 °C and in the cheese after one week in the refrigerator. The most represented groups were alcohols, ketones and acids.
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Production technology of wine sausage with reduced salt content
Martonová, Rebeka ; Punčochářová, Lenka (referee) ; Mikulíková, Renata (advisor)
The aim of this bachelor thesis was preparation of wine sausages with reduced salt content, followed- up by sensory analysis. The theoretical part generally characterizes meat and meat products, sodium chloride and its importance in food. In the next chapters, the paper deals with sensory analysis of samples and analytical method for determining the concentration of elements in biogenic samples, in particular inductively coupled plasma - optical emission spectrometry. The experimental past focuses on the evaluation of data from sensory analysis using the Kruskal- Wallis and Spearman test. The samples were analyzes using ICP-OES method. The analysis determined the concentration of sodium and potassium in the samples before and after roasting.
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Application of herbal extract into suitable food product
Chmelařová, Adéla ; Saláková, Alena (referee) ; Vítová, Eva (advisor)
This master’s theses deals with a production and characterization of hard candies, a type of non-chocolate sweets. Methods of candies production were optimised with focus mainly on boiling temerature which significantly affects product consistency and stability. Production process optimisation was based on methods of sensoric analysis and Karl-Fishcher titration used to determine the water content in the product. Plant extracts Plectranthus amboinicus and Aronia melanocarpa which were applied to hard candies are rich source of bioactive compounds upon which prepared candies were characterised. Optimal conditions for candies production were – boiling temperature 155 °C, volume of citric acid 0,4 %, volume of Plectranthus extract 2 % and volume of Aronia extract 3 %. There were 42 volatile compounds identified in a sample containing 2 % of Plectranthus extract. Based on their content , the most significant compounds were carvacrol (8,44 %), carotol (1,47 %) and levomenthol (0,99 %). Total content of polyfenols was measured to be 7,10 ± 0,55 mgg-1 per 1 g of hard candy sample, antioxidant activity of a sample was 66,19 ± 1,80 gml-1. It was identified that 42 of volatile compounds were present inside the sample with 3 % of Aronia extract. The most significant being carotol (30,67 %), menthol (1,52 %) and thymol (1,39 %). The overall presence of polyphenols was measured to be 13,87 ± 1,12 mgg-1 per 1 g of the candy sample, the antioxidant activity of the sample was 115,00 ± 2,86 gml-1.
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Sensory quality of selected types of sweets
Michalíková, Veronika ; Němcová, 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.
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