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Effect of preservatives on the sensory properties of ham
Bělohoubková, Tereza ; Hudečková, Helena (referee) ; Mikulíková, Renata (advisor)
The Master’s thesis contemplates the effect of additives on sensory properties of ham. The theoretical part incorporates history of meat product preservation and characterization of ham from legislative and compositional point of view. Technological ham making process in the Czech republic as well as worldwide and nutritional value of cooked ham are described. Further on the thesis contains a description of traditional and new sensory evaluation methods. Discussion of current solution of the issue concludes the theoretical part. In the practical part technological highest standard ham making process was optimalized, without the use of industrial manufacturing devices. Samples of ham containing nitrite salting mix and sodium nitrate along with a ham sample without the additon of preservatives were prepared. Total content of moisture, proteins, ash and fats was determined in these samples by regular standardized methods, that were statistically compared by paired test or analysis of variance (ANOVA) with results obtained by FoodScanTM instrument. Fatty acids content was determined by gas chromatography with FID detector in samples containing additives and a sample without additives. Effect of additive adittion in ham on nutritional characteristics, fatty acids content and on concentration of TBARS (lipid oxidation products) was investigated. Within sensory analysis effect of additives on sensory properties of ham was studied by CATA method. Sensory panel consisted of consumers. In the first sensory analysis of ham samples with addition of preservatives (nitrite salting mix, sodium nitrate, sodium acetate and sodium lactate) consumers picked ham containing nitrite salting mix as the most acceptable. The chosen sample served as a base for the second sensory analysis of samples containing antioxidants (sodium erythorbate, butylhydroxyanisole, butylhydroxytoluene, sodium ascorbate) and stabilizers (sodium hydrogen phosphate and potassium phosphate). In the second sensory analysis the consumers had difficulty distinguishing the samples. Part of the sensory analysis was a marketing research and a study of ham additives perception from a consumer’s point of view.
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Recipe of a food supplement based on bioactive substances isolated from Prunus spinosa
Červinková, Zuzana ; Hudečková, Helena (referee) ; Kovalčík, Adriána (advisor)
Blackthorn fruits (Prunus spinosa) are small blue-purple drupes containing a range of bioactive substances that give them diverse biological effects. They are traditionally used not only in folk medicine, as they are attributed with many preventive and therapeutic effects. The presented master´s thesis deals with the preparation and characterization of an ethanol extract and dietary supplements based on bioactive substances isolated from the fruits of blackthorn. The ethanol extract was prepared by maceration fresh Prunus spinosa fruits in 40% alcohol. The extract was analyzed for the polyphenols (2111.39±11.32 mg GAE/l), flavonoids (903.89±5.08 mg CAE/l) and anthocyanins (165.24±0.38 mg CGE/l) content, antioxidant (11.99±0.40 mmol TE/l) and antimicrobial activity, phenolic compounds profile and sugars profile. The ethanolic extract exhibited antibacterial effect against the gram-positive bacterium Micrococcus luteus and gram-negative bacterium Escherichia coli but was not effective against the yeast Candida glabrata. After gentle concentration on a vacuum evaporator, the extract was used to prepare a dietary supplement. Two types of dietary supplements were prepared, namely gelatine candies with blackthorn fruit extract and gelatine capsules filled with lyophilized fruit powder. The nutritional profile of these products, content of bioactive substances (i.e. total polyphenols, flavonoids, and anthocyanins), phenolic compound profile and antioxidant activity were characterized. Additionally, the release of polyphenols was monitored during a simulated in vitro digestion. The gelatine candies with different extract concentrations (5, 10, 15 and 20 %) were subjected to sensory evaluation, where the aim was to optimize the addition of the extract to the gelatine matrix. According to the preferences of the evaluators, the sample with 15 % extract was rated as the best in terms of overall taste. In the ranking test, this sample was ranked second, behind the sample with 5 % extract, which, on the other hand, received a worse sensory profile rating. The thesis also included monitoring the effect of freezing, lyophilization, and drying on the bioactive compounds content (i.e. total polyphenols, flavonoids, anthocyanins) and antioxidant activity of Prunus spinosa fruits. The highest contents of total polyphenols (57.49±0.33 mg GAE/g DW), flavonoids (45.75±0.12 mg CAE/g DW) and anthocyanins (6.41±0.19 mg CGE/g DW) were quantified in lyophilized fruits, but the highest antioxidant activity (281.72±0.70 mol TE/g DW) was observed in frozen fruits. A statistically significant moderately strong positive correlation (0.641) of antioxidant activity and total flavonoids was observed for the analyzed samples. The results of the thesis showed a great potential for the use of blackthorn berries in the nutraceutical industry, where they can contribute as active additives to increasing both the bioactive and nutritional quality of dietary supplements.
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Study of the effect of microbial degradation of lignin on its molecular weight
Fialová, Tereza ; Hudečková, Helena (referee) ; Kovalčík, Adriána (advisor)
This diploma thesis deals with the microbial degradation of lignin using wood-degrading fungi Fomitopsis pinicola and Lenzites betulina. In the first phase of the experimental part, media screening was carried out, the aim of which was to select the best media for fungal growth and production of ligninolytic enzymes. Based on the determination of activity, in the next step, the conditions for their production were optimized in selected media. As part of these experiments, the optimal concentration of lignin and glucose was selected for subsequent cultivations. Commercially available lignin was used as substrate. Based on the results of measured enzyme activities, Lenzites betulina was selected as the better producer. The most produced enzyme of this fungus was laccase, followed by manganese-dependent peroxidase and the least lignin peroxidase. Further experiments were performed only with L. betulina. In the next part of the experiment, lignin was characterized, and its properties compared before and after microbial degradation. Its molecular weight was determined by SEC-MALS and the change in structure by FTIR. The molecular weight of lignin decreased after cultivation and a change in its structure was also noted. The results show that the microbial degradation of lignin was successful.
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Use of some fractions of technical hemp in cosmetics
Gregarová, Lenka ; Hudečková, Helena (referee) ; Márová, Ivana (advisor)
Cannabis sativa is a versatile herb which is known for several thousand years and contains a variety of active substances. This thesis is focused on the use of some extracts of hem in cosmetics, specifically in hair cosmetics. The first part focuses on the Cannabis sativa, introducing the active contained substances and the overall processing of the plant. In the second part were experimentally determined the active substances in five extracts from different varieties, that were supplied from industry. Extracts were compared based on the extraction yield of antioxidants, chlorophylls, phenolic compounds, flavonoids and cannabinoids. Subsequently, a hair shampoo was prepared with the addition of hemp extracts and hemp hydrolysate. Lastly, the inhibitory effect against microorganisms was monitored for extracts and shampoos finally. Beneficial biologically active substances were detected in hemp extracts, wherein higher levels were measured in ethanol extracts. The extracts were also able to inhibit the growth of certain microorganisms. Satisfactory results on hair were observed with the prepared shampoo.
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UTILIZATION OF FOOD PROCESSING WASTE FOR LACTIC ACID AND ETHANOL PRODUCTION
Hudečková, Helena ; Kráčmar, Stanislav (referee) ; Buňka, František (referee) ; Márová, Ivana (advisor)
The doctoral thesis is focused on the microbial production of lactic acid and ethanol using food processing waste as substrate. Coffee processing waste (spent coffee grounds), wine production waste (grape pomace) and orange processing waste (orange peel) were chosen as substrates for experiments. The theoretical part is dedicated to summarizing current knowledge about waste from food production and possibilities of its processing. It also deals with selected metabolites (lactic acid, ethanol) to which these wastes can be used. Part of the experiments was focused on the characterization and optimization of hydrolysis to maximize the amount of fermentable saccharides. Different combinations of chemical, physical and enzymatic hydrolysis of selected substrates have been tested. Subsequently, a suitable strain for lactic acid and ethanol production was searched for. In the case of lactic acid production, 7 bacterial strains were selected (Lactobacillus casei CCM 4798, Bacillus coagulans CCM 2013, Bacillus coagulans CCM 2658, Lactobacillus rhamnosus CCM 1825T, Lactobacillus delbruckii subsp. bulgaricus CCM 7190, Lactobacillus plantarum CCM 7039T, Streptococcus thermophilus CCM 4757). These strains were first cultivated on the synthetic media containing different kind of saccharides. Afterward, the cultivation on the waste biomass hydrolysates were tested. In the case of ethanol production, 2 yeast strains kmeny (S. cerevisiae CNCTC 6646 a S. cerevisiae CNCTC 6651) were cultivated on hydrolysates of individual waste substrates. Subsequently, the experiments focused on the production of lactic acid and ethanol on hydrolysates of waste biomass in bioreactor were done. The last part of this doctoral thesis deals with the microaerobic pretreatment of lignocellulosic biomass to increase the production of organic acids during the acetogenic phase of anaerobic digestion.
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Production of organic acids by fibrous microscopic fungi and utilization of their biomass for removal of risk elements
Juglová, Zuzana ; Hudečková, Helena (referee) ; Urík,, Martin (advisor)
The aim of this bachelor thesis was to determine the most advantageous method for production of organic acids by microscopic flamentous fungus Aspergillus niger and to evaluate mercury bioaccumulation efficiency on collected fungal biomass. The theoretical part focuses primarily on utilization, metabolism and production on individual organic acids. This is followed by section focused on the toxicity of mercury and the principles of bioaccumulation of heavy metals in biomass. The experimental part focuses mainly on the optimization of cultivation, determination of content of produced organic acids, depending on the type of cultivation. Second point of practicle part is evaluating of mercury bioaccumulation depending on the initial concentration of mercury in solution. In overall comparison, the best type of cultivation is dynamic. Higher biomass yeild resulted in higher production of organic acids. The higher biomass synthesis is also beneficial for bioaccumulation of mercury.
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Encapsulation of probiotics for use in nutritional products for children
Šmídová, Veronika ; Hudečková, Helena (referee) ; Skoumalová, Petra (advisor)
This bachelor thesis is focused on optimization and development of probiotic food supplement with attractive look and active ingredient, like prebiotic or “superfood”, which are there for afford useful substances for organism. In the theoretical part is focused on probiotics and its encapsulation, also on prebiotics, which are used for work and screening probiotics food supplements in our market. The practical part is focused on optimization of composition of new probiotic food supplement, polysaccharide particles in the shape of a teddy bear were prepared. At first, the basic composition was optimized, as the best alginate-agar particles were determined. Addition of nutritionally valuable ingredients was also optimized. Particles with inulin, acerola, chia fiber, yacon syrup, chlorella and spirulina were prepared. Another part of this work was focused on the determination of the viability of probiotic bacteria Lactobacillus acidophilus and Bifidobacterium breve in various forms and after exposed to model digestion. The highest viability of the cells was measured after encapsulation of lyophilized cells into a polysaccharide particle. Prepared particles were finally subjected to a sensory analysis.
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Analysis and characterization of beta-glucans from some natural sources
Vít, Radek ; Hudečková, Helena (referee) ; Márová, Ivana (advisor)
The aim of the bachelor thesis is to test and characterize commercially available products with declared -glucans content. The theoretical part describes -glucans, their possible sources, properties and utilization. Further, the theoretical part is focused on methods for determination of -glucan content. Saccharomyces cerevisiae yeast and oyster mushroom fungus are available as commercial sources of -glucans. Next individual groups of the active substances and principles of the methods used for their characterization are described too. In experimental part of this work the extracts from five commercially available sources of -glucans were prepared and characterized. Antioxidant activity, total polyphenols, proteins and carbohydrates were determined. For selected products, the content of vitamin C using HPLC and the lipid content using GC-FID were determine as well. An enzymatic method was used to determine the -glucan content. Two samples of the highest antioxidant activity were then subjected to antimicrobial and MTT tests.
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The trends of spending leisure time in Náchodsko region (a comparative study in the rural area)
Kozáková, Helena ; Hudečková, Helena (advisor) ; Tomáš, Tomáš (referee)
Free time in today's life is becoming more and more important. The development of modern society and specialization of labor market today divides more obviously time for responsibilities and pastime. Leisure time is a very individual matter and its form is dependent on many aspects. Age and the size of the place of residence belong to those aspects that influence spending our free time. The relation between them became the core topic of this thesis. The practical part is based on my own research in three urban areas of different size in Nachod district. The research analyses the offer of free time activities as well as the attitude of the inhabitants in relation to their age and the size of town. The core task of this practical part was to look for any causal links. Deeper analysis shows that there is a certain coherence between the age of inhabitants, the size of their town and the style of spending leisure time, nevertheless this influence is not very significant. It is above all a very individual matter.
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Leisure time in small communities in Prague suburban area
Šubová, Alžbeta ; Hudečková, Helena (advisor) ; Kučerová, Eva (referee)
The thesis is focused on spending free time of inhabitants from two small villages in Prague sururban area and if there is any other option how to improve efficiency of spending free time of local inhabitants. The theoretical part concerns free time: its definiton, history, functions, factors which influence spending of free time. Essay gives information about two surveyved willages and its local options of free time activities.
The practical part used questionnaires and interviews which are described at the end of this thesis.
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