|
|
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.
|
|
|
Production of pates with the addition of mushrooms
Tóthová, Martina ; Holub, Jiří (referee) ; Mikulíková, Renata (advisor)
This bachelor thesis deals with the sensory evaluation of pâté with mushrooms. First the 3 samples of pâtés were made to select the right concentration of mushrooms for sensory evaluation. Then the 7 samples of pâtés which contained different texture and types of mushrooms were produced. In the theoretical part pâtés are characterised, their manufacturing and types of pâtés are described. The part of literature search is description of mushrooms in general, their composition and description of mushrooms which were used for production of pâtés. Another topic is description of conditionals and methods of sensory analysis. The experimental part is focused on the production of pâtés for two sensory analyses, evaluating the heat treatment and sensory analysis. The content of vitamin D in the samples of pâtés was analysed by liquid chromatography. Processing of results of sensory analysis of pâtés was determined that the best samples were pâtés with milled champignons and champignons which were add in blender.
|
|
|
Phloridzin content in selected apple varieties
Křehlíková, Jana ; Mikulíková, Renata (referee) ; Diviš, Pavel (advisor)
Phloridzin, a phenolic compound found in Malus genus, was targeted in this study for detection in apples and apple-based foods via HPLC. The research aimed to assess phlorizin’s potential as a marker for confirming apple presence in food, addressing food authenticity concerns. The methodology encompassed method optimization for sample preparation, considering solvent selection and oxygen impact on stability. Analysis revealed significant phloridzin distribution among apple varieties (Golden Delicious, Red Delicious, Granny Smith, Gala, Champion, Jonagold), averaging 17 ± 10 mgkg1. Further, 15 fruit products were surveyed for phloridzin content, with 5 non-apple-labelled foods also analysed. Phloridzin proved effective in detecting undeclared apple presence in jams, fillings, and fruit purees, highlighting potential for authenticity verification. However, fruit drinks and juices exhibited inconclusive results, suggesting a need for improved sample preparation and analysis methods.
|
|
|
Study of the Selected Types of Sulphur Compounds in Beer and Brewing Materials
Mikulíková, Renata ; Ventura, Karel (referee) ; Ventura, Karel (referee) ; Čáslavský, Josef (referee) ; Márová, Ivana (advisor)
Much attention has been recently devoted to sensorially active substances affecting beer quality in the Czech Republic and worldwide. Among them, the heterocyclic and sulphur containing compounds play an important role, some of them with high sensorial activity even in extremely low concentrations. Trace amounts of these compounds, which can be frequently found in foods, participate in formation of their aroma and this effect can be generally evaluated as favorable However, in malt or beer it is true only to a limited extent and the presence of heterocyclic and sulphur containing compounds are in this respect assessed rather unfavorably. The aim of the present study was to provide a survey about of problems in the field of sulphur containing compounds in barley, malt and beer, to describe metabolic paths leading to their formation and to verify experimentally possibilities of their determination using modern analytical methods. Sulphur-containing amino acids are a natural part of barley, malt and beer and are precursors of the origin of volatile sulphur substances. The most frequently occurring sulphur amino acids, metionine, cysteine and homocysteine, were selected for analytical monitoring. The method of gas chromatography was used to determine sulphur-containing amino acids in barley, malt and beer. Prior to the analysis, sulphur-containing amino acids were derived and volatile N(O,S)-ethoxycarbonyl propyl esters were formed; they were subsequently analyzed using the gas chromatography with mass detector (GC/ MSD) and the gas chromatography with flame photo detector (GC/ FPD). Direct analysis of sulphur volatile substances is possible only rarely as they are found in the analyzed matrices (malt, beer) only in very low concentrations ( g/kg,l - ng/kg,l). Before the analysis, the analytes must be extracted from the matrix and concentrated. The modern analytical methods SPME (Solid Phase Micro Extraction), SPDE (Solid Phase Dynamic Extraction) and TDAS (Thermal Desorption Autosampler) were experimentally compared for the extraction and subsequent concentration of sulphur volatile substances. The method of gas chromatography with flame photo detector was used to determine sulphur volatile substances. Following volatile sulphur substances were monitored: dimethyl sulphide, dimethyl disulphide, dimethyl trisulphide, carbon disulphide, ethyl sulphide, diethyl disulphide, methionol, 3-methylthiophen, ethyl thioacetate, 2-methyl-1-buthanthiol. Only metionine was detected in significant amounts in the barley samples analyzed. Not only content but also dependence on a variety and locality were studied. Further, changes in methionine, cysteine and PDMS content during malting were followed. Results proved a significant decline in these substances content depending on the kilning temperature. Three types of fibers were tested for the analyses of the selected volatile sulphur substances in beer in the SPME method. PEG - a fiber with stationary phase Carbowax, PDMS - a fiber with stationary phase polydimethylsiloxan and a combined fiber CAR/PDMS - Carboxen and polydimethylsiloxan. Carbon disulphide, methionol, dimethyl sulphide, 3-methylthiophen and diethyl disulphide were detected with this method. Content of the other analyzed volatile sulphur substances was below the limit of detection. Further was tested usage the SPDE and TDAS methods. Both methods appear to be the suitable for the determination of volatile sulphur substances in beer.
|
|
|
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.
|
|
|
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.
|
|
| |
|
|
Preparation and characterization of packaging films based on beta-keratin
Měšťánková, Zuzana ; Mikulíková, Renata (referee) ; Kovalčík, Adriána (advisor)
This diploma thesis deals with keratin isolation from poultry feather waste and preparation of keratin-polymers composite films utilizing isolated keratin. The main goal was to isolate keratin from poultry feathers by hydrolysis and compare yield of diverse hydrolysis types. The most efficient was hydrolysis using 0.5% sodium hydroxide with yield 480 g of keratin per 1 kg of chicken feathers. Structure, morphology and thermal properties of isolated keratin was analyzed. Comparison with protein molecular weight standard it was revealed that hydrolysis cleaved keratin to macromolecules smaller than 15 kDa. Scan electron microscopy showed that size of lyophilized keratin particles was in the order tens of µm and had an irregular shape. Further, composite films based on isolated -keratin and other polymers were prepared. Thermal analysis showed, the addition of keratin significantly reduced the thermal stability of composite films. Analyses revealed that Polyvinyl alcohol composite films reached the best mechanical properties. For example, an addition of 0.25 g of keratin per 1 g of polyvinyl alcohol increased the tensile elongation by up to 68.9%. Moreover, the film based on chitosan and keratin had antibacterial properties. The results demonstrate that it is able to efficiently isolate keratin from poultry feather waste by alkaline hydrolysis and isolated keratin can be utilized to prepare potentially applicable keratin-polymers composite films.
|
|
|
Determination of athenticity of plant foods by molecular techniques
Plášková, Anna ; Mikulíková, Renata (referee) ; Němcová, Andrea (advisor)
The aim of presented diploma thesis was to determination of authenticity of fruit baby foods for early infant feeding using molecular methods. In the experimental part, isolation kit was used for isolation of plant DNA from fruits (strawberry, apricot, raspberry, apple) and from six commercial fruit products for children. Isolated DNA was characterized and verified using PCR methods with primers specific for plant rDNA (ITS2). Specific primer pairs were designed to amplify DNA for the detection of one fruit species. Primer specificity was assessed with four fruit species. A mixture of fruit puree from the two fruits was used to determine the sensitivity of the multiplex PCR assay. Six commercial fruit products were evaluated to verify the applicability of the multiplex PCR assay. The methodology of molecular detection of fruit DNA by qPCR and multiplex qPCR (duplex) includes approaches, which enable to detect two fruits (strawberry-raspberry, apricot-apple) in one reaction and thus reduces time and money requirements.
|
|
|
Analysis of autenthicity of food products with fruit component
Prachárová, Adriana ; Mikulíková, Renata (referee) ; Márová, Ivana (advisor)
The aim of this thesis was to determine the authenticity of fruit food for infants using molecular and instrumental methods. In the experimental part, plant DNA isolations from fruit leaves (peaches, apricots, plums and apples) and bananas were performed. Further, DNA was isolated also from five commercial products, and from model mixtures that were prepared in terms of content identical to the commercial mixtures. The isolated DNA was characterized and verified by qPCR with plant DNA-specific ITS2 primers. Three triple primer pairs were selected, and their specificity was evaluated when performing multiplex PCR. This method makes it possible to detect more types of fruit in one reaction, reducing the economic and time requirements for detection. As none of the selected primer pairs were sufficiently specific for the apricot, the evidence from the plum and peach was further realized using duplex PCR. High resolution melting curve analysis was used for better DNA type recognition. Subsequently, agarose gel electrophoresis was performed to analyse the fragment lengths. Furthermore, experiments have been made to identify some specific phenolic substances in commercial and model fruit mixtures by HPLC. Since phenolic substances are degradable under unsuitable storage conditions, the presence of individual compounds was not detected by this method.
|
guest ::
RSS feed.