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Influence of insect´s components in fish feed on production, health and quality of fish.
HLÁVKOVÁ, Markéta
The first part of my work is devoted to review of alternative components in feeds for fish with special focus on insect. The second part of my work is based on the feeding experiment. Rainbow trouts (Oncorhynchus mykiss) were bred in the aquaria at the Faculty of Fisheries and Protection of Water JU in Vodňany. Experiment was performed in three replications, in 300 litre aquaria with 8 - 10 fish per aquarium. Fish were divided into 5 groups according to the type of feed used. Control group was fed the commercial granule feed and the other four groups were served insect in certain percentage. It was a cricket (Acheta domesticus) and the maggots of giant mealworm beetle (Zophobas morio).Weight and length of fish was registered three times during 2 months of experiment. The sensory analysis of fish meat was done for evaluation of aroma, taste, after taste and consistence of fish muscle. The results show that diet containing insect did not significantly influence weight and growth. In the contrast, sensory analysis proved the difference in analysed parameters. The feed containing only insect was identified as an inappropriate alternative feed. In conclusion, the insect can be used as the alternative feed for fish in the aquaculture. Nevertheless, it is recommended to combine the insect with commercial feeds.
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Extending of shelf life of chilled fish products
PFLUG, Róbert
This diploma thesis was focused on the possibilities of extending the shelf-life of fish products by dipping containing seven commercial additives. ANTIBAK, MIC STAB, Bakont, SEA-F75, Misocarine LR, SAFE A Plus and AMX liquid. The effectiveness of these substances on the extending of shelf-life was evaluated on the basis of tests of TVC (total viable count), level of fat and protein oxidation, determination of nutritional parameters of muscle, and finaly sensory analysis. Experimental species were 2 important commodities for the Czech aquaculture rainbow trout (Oncorhynchus mykiss) and common carp (Cyprinus carpio). The project was divided into 6 sub-stages. During testing was the initial number of aditives (7) limited by stepwise selection for 2 preparations. Namely Bakont and AMX liquid, which were tested further on trout (filet with skin and scales) and carp (filets with skin without scales) chilled bulk and chilled packaged under vakuum. For trout was studied antimicrobial effect of dipping on eviscerated fish with the head with- or without gills. Treated trout fillets in bulk and vakuum-packed showed significantly less abundance of muscle mikroflora. In the case of carp fillets chilled bulk we can not say that the bath had influence on the CMP in meat. However, the combination of dipping and vakuum packaging was singnificantly different between the control and product Bakont. AMX liquid was not applied in this case in sufficient dose or in sufficient time to carp muscle. A positive finding is that the application of the aditives to the product "eviscerated trout with head" it does not matter, whether the gills are left in fish or not. However, in all cases the analysis of the presence of pathogens Escherichia coli, Salmonella spp. or Listeria monocytogenes were negative. From the results of sensory analysis can be concluded, that the substances contained in aditives are not reflected in the sensory properties of tested fish.
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Testování schopnosti hodnotitelů při senzorické analýze
ZELENÁ, Andrea
The present thesis deals with testing the capabilities of assessors in sensory analysis focused on examining the sensitivity of the sense of taste. Evaluation was carried out among students of Faculty of Agriculture, University of South Bohemia in Ceske Budejovice, in splitting into different groups according to gender, age, field of study, health status, in terms of smokers-nonsmokers, depending on season and time of day at which the evaluation was conducted. At present, when occures the glut of food in economically developed countries, consumer visors besides nutritional choices and wholesomeness also sensory quality, which is the only one he can consider himself on the spot. Foods are preferred or rejected by the feelings that have developed on the basis of experience. It was therefore necessary to create an objective analytical method for assessing foods to ensure the elimination of interferences and subjective factors. A suitable method is called sensory analysis, in which the organoleptic properties of food are determined solely by human senses. It affects such qualitative indicators, which can not be characterized by instrumentation. The results obtained indicate that there are differences within the studied groups. More successful were: women than men, completely healthy assessors than assessors with mild symptoms of colds, winter (December 2014) group of assessors than spring (April 2015) group, morning group (7:00 to 10:00) than afternoon (12:00 to 15:00) group, assessors aged 22 years than other age groups, assessors Animal science than assessors in other fields. Smokers were surprisingly more successful than nonsmokers.
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The presence of allergenic aroma compounds in sweets
Plevová, Petra ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This thesis deals with the determination of aroma active compounds in non-chocolate confectionery and their influence on the sensory properties of these sweets. The theoretical part is focused on the 26 potentially allergenic substances and their determination by SPME-GC-FID (a solid phase microextraction, gas chromatography with flame ionisation detector) and sensory analysis. In the experimental part SPME-GC-FID method was used to identify and quantify aroma active substances contained in the selected samples of confectioneries commonly available in food market and find out influence of presence and amounts of these substances on sensory profile of selected confectionery.
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Fragrance Allergens in Foods and Everyday Use Products
Divišová, Radka ; Buňka, František (referee) ; Hojerova,, Jarmila (referee) ; Omelková, Jiřina (advisor)
Fragrances are added to food, cosmetics and other products primarily for enhancement of their sensory quality (taste and/or aroma). However, the usage of these compounds is associated with the wide range of various adverse biological effects. Some fragrances widely used in cosmetics are proved to cause e.g. skin sensitization, rashes, dermatitis, headache, cough etc. To protect the health of consumers, European union approved the cosmetic directive (ES/1223/2009) that requires the labeling of 26 allergen fragrances on the final product label, if concentration exceeds the given level (0,01 % for rinse-off and 0,001 % for leave-on product). However, some producers hide the presence of allergens in the final product under the general term „aroma“. For this reason it is very important to monitor the content of these substances in cosmetic products. Fragrances are found not only in cosmetics, but the various types of food are also aromatized by them. Unlike cosmetics, the food producers are not obliged to label the presence of fragrance allergens on the packaging. Therefore, the monitoring of these fragrances is highly desirable because of the potential health risks they pose. The aim of this study was to develop a method for simultaneous determination of regulated fragrance allergens in food and everyday use products. The method based on extraction of analytes by solid phase microextraction coupled to gas chromatography with FID detection (HS-SPME-GC-FID) was chosen on the basis of the literature review. The fiber CAR/PDMS provided the highest extraction efficiency among the SPME fibers tested. Univariate and multivariate data analysis were used to optimize the main parameters affecting microextraction process. The final method validation was performed in terms of linearity, repeatability, reproducibility, recovery, limits of detection and quantification. The optimized and validated method was applied to a wide range of products including cosmetics, aromatized food and fragranced toys. These products were also subjected to sensory evaluation especially in terms of taste and/or aroma (i.e. flavour), which may be associated with the content of the monitored fragrances. The profile test (EN ISO 13299) and seven-point category ordinal scale (ISO 4121) were used for sensory evaluation.
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Study of Factors Influencing Creation of Volatile Aroma Active Compounds in Natural Materials
Loupancová, Blanka ; Vávrová, Milada (referee) ; Kráčmar, Stanislav (referee) ; Fišera, Miroslav (advisor)
The production of high-quality foods requires the precise control of factors influencing their quality. The aim of this doctoral thesis was to monitor the influence of sterilization heating and storage time and temperature on selected parameters of model food matrix using suitable physical, chemical and sensory methods. Sterilized processed cheese was chosen as the model matrix. Processed cheeses are milk protein concentrates, produced by melting of mixture of natural cheeses, emulsifying salts, water and other dairy and/or non dairy ingredients. Desirable transformation of this mixture to homogenous, smooth, shiny mass with desired textural, structural, rheologic and sensory properties is caused by using high temperature (about 80-100 °C) during melting. Sterilized processed cheese is subjected to additional sterilization heating (above 100 °C) after production, significantly elongating its durability. The processed cheeses (dry matter 40 % w/w, fat in dry matter 45 % w/w) were analyzed in this work, the part of them was sterilized (117 °C 20 min). Cheeses were stored at various temperatures (cold 6 ± 2 °C, laboratory 23 ± 2 °C and elevated 40 ± 2 °C), sterilized cheeses for 2 years, non sterilized for 1 year. During storage, the samples for physical (instrumental measuring of colour and texture), chemical (assessment of fatty acids and aroma compounds) and sensory (paired preference test, ranking test and evaluation using scale) analyses were taken at regular intervals. The influence of sterilization heating and for another the influence of storage conditions on mentioned parameters were investigated. Non sterilized processed cheese kept their very good quality during all the declared durability (4 months), however, then the significant worsening of most sensory properties was observed. In consequence of sterilization heating the changes of cheese colour and texture were observed, confirmed by both sensory and instrumental assessment. The impairment of taste and aroma was also found. These changes are obvious immediately after production and differences were observed during all the durability. In the case of sterilized processed cheese, the significant impairment of single sensory properties was determined, the highest in the case of texture, taste and aroma. The results of instrumental techniques confirm conclusions from sensory evaluation. The measurements of colour and texture vindicate the formation of darker colour (increasing total difference of colour delta E*) and higher hardness (increasing Fmax) of sterilized processed cheeses, continuing during storage. The worsening of taste and aroma is in accordance with lower content of aroma active compounds and selected fatty acids.
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Statistical methods for evaluation of sensorial data
Kozielová, Magda ; Kříž, Oldřich (referee) ; Michálek, Jaroslav (advisor)
\par The thesis deals with the statistical evaluation of data gained by the sensory analysis of the foodstuff. It brings a selection of the suitable statistical tests, a detailed analysis of these tests and their comparision based on the particular power functions for given parameters. As an important part of the thesis, there is a creating of custom software for the evaluating of sensorial data.
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Assessment of chosen aroma compounds in foods and cosmetics
Obrdlíková, Blanka ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This diploma thesis is focused on the problematic of assessment of allergenic aroma compounds in various matrices. In the frame of European legislation 26 of potentially allergenic compounds are stated, whose content in cosmetic products is limited. In the case of foods there is not such restriction so far. In the experimental part, the allergenic aroma compounds in chosen samples of cosmetic and food samples were identified and quantified using Solid phase microextraction in conjunction with gas chromatography. Sensory evaluation of aroma or taste is also included.
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Complex characterisation of gooseberry fruits
Rodzíková, Martina ; Vespalcová, Milena (referee) ; Vítová, Eva (advisor)
This thesis deals with the assessment of aroma active compounds in gooseberry and sensory analysis of it focusing on flavour. The theoretical part describes general characteristics, biological marks and properties of selected varieties, healing abilities, the active substances contained in gooseberry fruits and their use. The aim of the experimental part was to determine aroma-active substances contained in fruits of nineteen selected cultivars of gooseberry using SPME-GC-FID method. In total 45 volatile compounds were identified, among them 17 alcohols, 11 aldehydes, 6 ketones, 9 esters and 2 acids. For a better identification one sample (Captivátor variety) was also analysed using GC-MS with purge and trap extraction. Pentan-1-ol, hexanal, pentanal, ethylethanoate, ethylbutanoate, methylethanoate, methylbutanoate and ethanol were confirmed using mass spectra. Only several cultivars were selected for the assessment of overall sensory quality and palatability of fruits. Karmen and Remarka varieties were considered as the best samples by assessors.
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Assessment of aroma active compounds in currant
Lišková, Michaela ; Babák, Libor (referee) ; Vítová, Eva (advisor)
This master thesis deals with the assessment of aroma active compounds in fruits of currant (Ribes spp.). The theoretical part was focused on basic characteristics and chemical composition of currants, as well as the basic principles of techniques used: solid phase micro extraction (SPME), gas chromatography (GC) and sensory analysis. The main aim of the experimental part was to determine aroma active compounds in currants using SPME-GC-FID method. The profile and scale tests were used for assessment of sensory quality and tastiness of fruits. In total 18 varieties, among them 6 white, 6 red and 6 black currants, were evaluated. Fifty aroma active compounds were identified including 21 alcohols, 10 aldehydes, 2 acids, 8 ketones and 9 esters. The results were statistically evaluated using principal component analysis (PCA) to investigate the influence of single compounds on sensory quality of fruits.
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