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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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Possibilities of enhancing the flavour of fresh cheeses by the addition of spices
Bandarenka, Andrei ; Vítová, Eva (referee) ; Mikulíková, Renata (advisor)
This bachelor thesis deals with the preparation and sensory evaluation of fresh cheeses with the addition of different types of spices. The theoretical part of the thesis is focused on the characteristics of the spices used and the description of the most important components of the milk. The characteristics of the cheeses, their distribution, composition and basic production procedures are also presented. At the end of the theoretical part, the sensory evaluation and methods of determination of antimicrobial activity of substances were described. The experimental part of the thesis is focused on the production of fresh cheeses with the addition of different spices (red pepper, turmeric, cumin and fenugreek) followed by the sensory evaluation of these cheeses. Samples of fresh cheeses were produced at the Faculty of Chemistry of Brno University of Technology, where their sensory analysis was carried out. The aim of the sensory evaluation was to determine the best seasoning for the cheeses. Another part of the experimental work was devoted to the determination of antimicrobial activity of selected spices by the dilution method. The antimicrobial activity was tested against Gram-positive bacteria Micrococcus luteus and Gram-negative bacteria Serratia marcescens in water and in aqueous solution of dimethyl sulfoxide. On the basis of the data obtained from the sensory analysis and the antimicrobial test, it was found that the best of the spices used for fresh cheese is turmeric , which not only improves the sensory properties of the cheese but also has a strong antimicrobial effect.
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Application of herbal extract to non-chocolate jelly sweets
Phi, Lan Anh ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
This master’s thesis focuses on optimization of application of herbal extracts and powder into jelly sweets and comparing them to commercial products with a same flavour. Prepared and commercial samples were then characterized in terms of volatile substances, total phenolic content, antioxidant activity and sensory quality. Volatile compounds were determined by HS-SPME-GC-MS method, a verification of validation parameters (limit of detection and quantification, repeatability, reproducibility, retention time, retention index) was part of the thesis. The total phenolic content was determined by Folin-Cicalteu’s spectrophotometric method, antioxidant activity by TEAC method and sensory quality by sensory analysis. Optimal amount of extracts and powders were selected based on the sensory analysis. For the preparation of extracts and powders were used aromatic plants lemon balm (Melissa officinalis) and ginger (Zingiber officinale). Optimal amount of extract addition was the concentration 15 %, by the next sensory analysis was determined 1 % addition of the powder for both herbs. There were 32 volatile compounds identified in a model lemon balm jelly, which of 4 were allergens (linalool, Z and E isomer of citral, citronellol, Z and E isomer of geraniol). Total phenolic content in the sample was 755,5 ± 14,3 gGAE g–1 and antioxidant activity was determined on a value 2,73 ± 0,13 10–3 mmolTE g–1. Commercial lemon balm sample contained 54 aromatic compounds from which were 5 allergens – limonene, linalool, Z and E isomer of citral, citronellol, Z and E isomer of geraniol. Total phenolic content was 695,5 ± 9,8 gGAE g–1 and antioxidant activity was 2,67 ± 0,05 10–3 mmolTE g–1. There were 26 volatile compounds identified in the model ginger jelly, which of 4 were allergens (linalool, Z and E isomer of citral, citronellol, (Z)-geraniol). Total phenolic content in the sample was 511,0 ± 12,3 gGAE g–1 and antioxidant activity was determined on a value 1,87 ± 0,16 10–3 mmolTE g–1. The first commercial ginger sample contained 55 aromatic compounds and 4 of them were allergens (limonene, linalool, citronellol, (E)-geraniol). Total phenolic content in the sample was 224,3 ± 20,2 gGAE g–1 and antioxidant activity was determined on a value 0,95 ± 0,24 10–3 mmolTE g–1. The second commercial sample contained 32 volatile compounds, which of were 4 allergens – limonene, linalool, Z and E isomer of citral and (E)-geraniol. Total phenolic content was 569,9 ± 23,2 gGAE g–1 and antioxidant activity of the sample was 3,48 ± 0,08 10–3 mmolTE g–1. In terms of sensory properties, the prepared samples which had balanced sweet and sour taste with pleasurable optimal herbal taste, were preferred by evaluators.
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Fortification of bakery products with protein isolate from wheat bran
Bidmonová, Karolína ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
Proteins, as the major structural component of all cells and tissues, along with fats and carbohydrates, are a key macronutrient in human nutrition. An insufficient protein intake in the diet can lead to health problems and increasing protein malnutrition. Food fortification plays an important role in eliminating this protein deficiency. Wheat products, as a widely consumed food, seem to be a suitable commodity for protein fortification. Wheat bran was selected as a suitable source of protein due to its availability, protein content and relative simply method of a protein isolation. In the experimental part, the protein was extracted from wheat bran and used to prepare the mixtures. The mixture contained T530 flour and the 5%, 10% and 15% addition of the wheat bran protein isolate. From these mixtures, doughs were prepared and were subjected to chemical and rheological analysis. Finally, wheat baguettes with the addition of wheat bran protein isolate were made. The texture and taste properties of the baked products were verified by sensory analysis. The mixtures of flour and whey protein and a sample of unriched flour were also analysed to compare the results. Applied tests have shown that the addition of protein influences not only nutritional and chemical but also rheological properties. The addition of wheat bran protein isolate had a negative impact on the taste properties of the baguette Higher addition of BPI caused the increase of the bitterness of products. Taste optimization could be a topic for future study.
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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.
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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.
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Preparation and characterization of alcohol-free beers with different flavour
Benešová, Pavla ; Vávrová, Milada (referee) ; Márová, Ivana (advisor)
This diploma thesis deals with preparation and characterization of alcohol-free beers with different flavours. Five flavoured and four pure, commercially available beers were tested. Three alcohol-free beers were then selected and used for preparation of flavoured beers. Ingredients used for production of flavour were honey, raspberry, ginger and cranberry. Analysis was focused mainly on substances of phenolic nature. Flavoured beers were also tested in sensory analysis. Ingredients used for flavouring of beers and production of both alcoholic and alcohol-free beers are described in theoretical part of the thesis. Analysis of polyphenols, flavonoids, technological characteristics and anthocyanins was performed using spectrophotometric method. Phenolic substances were identified and quantified by HPLC/PDA. Ascorbic acid was analysed by HPLC-NH2/UV. Results proved an increase of polyphenols, ascorbic acid and anthocyanins during flavouring of alcohol-free beers in dependence of used ingredients. Sensory analysis showed that as the best rated was the Staropramen beer with raspberry flavour. On the contrary, flavoured Bernard beers were poorly rated.
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