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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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Characterization of lipids in fresh cheeses
Vaňková, Veronika ; Křikala, Jakub (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the determination of fatty acids in samples of fresh cheeses with or without the addition of plant extracts (rhyme, echinacea), produced in laboratory conditions at FCH BUT. The theoretical part of the thesis focuses on the general characterization of lipids and fatty acids. The next part discusses the characterization, division, and methods of cheese production, focusing mainly on fresh cheeses. The end of the work is devoted to gas chromatography as a method for the determination of fatty acids in cheese samples. The experimental part aimed to determine the content of fatty acids in the samples of fresh cheese. For the extraction of lipids from cheese samples, the choice of the method was according to ČSN EN ISO 1735. Acid esterification with boron trifluoride as a catalyst was used for the preparation of fatty acid methyl esters. The determination of fatty acid methyl esters was performed by gas chromatography with a flame ionization detector (FID). A total of 14 fatty acids were identified in all samples in a bound and free form. Myristric, palmitic, stearic and oleic acids predominated in all samples, which is in agreement with the knowledge of the composition of milk fat. The obtained results show, that even due to slight differences in the content of individual fatty acids, the addition of extracts does not affect the composition of fatty acids in fresh cheeses.
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Production of acid- vs. rennet-curd fresh cheese varieties
Veselá, Vendula ; Suská, Alžběta (referee) ; Vítová, Eva (advisor)
This bachelor thesis‘ focus is on the production and characterization of fresh cheese. Model samples of fresh cheese were produced on VUT Brno using purely acidic curdling (cream cheese culture – lactic acid), combined curdling (cream cheese culture + rennet) and acidic combined with heat curdling (acetic acid. 92 C) The samples were observed for their content of bound and free fatty acids, volatile (aromatic) substances and for their sensory quality. The goal was to determine the influence of the method of curdling on the observed factors. The fats were extracted from the samples using a mixture of diethyl ether and petroleum ether solvents. The fatty acids were esterified with acid to methyl esters under boron trifluoride catalysis and identified by the GC-FID method. In the cheese curdled by combined curdling, a greater amount of free fatty acids was detected compared to the other samples. No significant difference in the amount of bound fatty acids was observed. The greatest fatty acid content overall was observed in the cheese produced by acidic curdling. For identification and semi-quantification of the volatile (aromatic) substances, an HS-SPME-GC-MS method was used. 72 volatile compounds were identified in the samples. The percentual representation of different chemical groups varied significantly, the highest number of volatile substances was observed in the cheese produced by acidic curdling. Sensory evaluation was conducted using an evaluation scale as well as a ranking test. In all the observed indicators, the commercial sample was evaluated the best. The cheese produced by combined curdling was received rather negatively due to the sour taste. The second-best cheese was ranked to be the cheese produced by acidic curdling. The results show that the acidic curdling is the best for taste as well as aromatic substance and fatty acid content. If we, however, consider other factors such as the time taken, the cheese produced by combined curdling appears to be the best overall.
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Analysis of selected milk quality indicators and their impact on the yield and sensory properties of fresh cheeses
PLONER, Michaela
The aim of the diploma thesis was to evaluate the effect of cow´s milk quality on the fermentation, yield and selected properties of fresh cheese produced in laboratory conditions. For this purpose, there were 51 fresh cheese samples produced in three trials from 17 bulk milk samples originating from six farms. For milk and cheese sam-ples, selected analyzes were performed, and the obtained data were statistically eval-uated. The chemical composition, physicochemical and sensory properties, weight and yield of fresh cheese were evaluated depending on i) the time of fermentation, ii) the milk quality. As expected, the average values of pH, weight and yield of the fresh cheeses differed during the fermentation. The protein content, lactose and so-matic cell counts significantly influenced the yield and quality indicators of fresh cheese. The quality of milk also influenced the assessment of sensory properties, es-pecially color intensity and consistency. To achieve the optimal pH of fresh cheese (<5.00), the time of fermentation should be from 15 to 16 hours.
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Optimization of fresh cheese production and their characterization
Bittnerová, Eva ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
This thesis deals with the optimization of fresh cheese production and their characterization in terms of free and bound fatty acids, volatile (aromatic) substances and sensory quality. The theoretical part deals with the characterization of fresh cheeses, their production technology and sensory quality. It also includes options for determining volatile substances and fatty acids in fresh cheeses. In the experimental part, produced fresh cheese samples were analyzed during 14-day storage. The fat was extracted from fresh cheeses with a mixture of diethyl ether and petroleum ether, fatty acids were converted to the appropriate methyl esters by acid esterification with boron trifluoride as a catalyst and determined by gas chromatography with a flame ionization detector. Volatile substances were identified based on the comparison of mass spectra with a library of spectra and retention indices (according to Van den Dool and Kratz). The content of the identified substances was expressed semi-quantitatively using the areas of the respective peaks. A total of 20 fatty acids were identified, palmitic, myristic, stearic, capric, caproic and lauric acids predominated as representatives of saturated fatty acids, oleic acid as a representative of monounsaturated fatty acids, and linoleic acid was abundantly represented among polyunsaturated fatty acids. In terms of volatile substances, a total of 37 compounds were identified in the frozen samples and 42 compounds in the fresh samples. Alcohols, acids, aldehydes and ketones were the most represented. The results of the sensory evaluation show that the evaluators liked the stored cheeses better, so the cheeses maintain a good quality of min. for 14 days when stored in the refrigerator.
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Production of acid- vs. rennet-curd fresh cheese varieties
Veselá, Vendula ; Suská, Alžběta (referee) ; Vítová, Eva (advisor)
This bachelor thesis‘ focus is on the production and characterization of fresh cheese. Model samples of fresh cheese were produced on VUT Brno using purely acidic curdling (cream cheese culture – lactic acid), combined curdling (cream cheese culture + rennet) and acidic combined with heat curdling (acetic acid. 92 C) The samples were observed for their content of bound and free fatty acids, volatile (aromatic) substances and for their sensory quality. The goal was to determine the influence of the method of curdling on the observed factors. The fats were extracted from the samples using a mixture of diethyl ether and petroleum ether solvents. The fatty acids were esterified with acid to methyl esters under boron trifluoride catalysis and identified by the GC-FID method. In the cheese curdled by combined curdling, a greater amount of free fatty acids was detected compared to the other samples. No significant difference in the amount of bound fatty acids was observed. The greatest fatty acid content overall was observed in the cheese produced by acidic curdling. For identification and semi-quantification of the volatile (aromatic) substances, an HS-SPME-GC-MS method was used. 72 volatile compounds were identified in the samples. The percentual representation of different chemical groups varied significantly, the highest number of volatile substances was observed in the cheese produced by acidic curdling. Sensory evaluation was conducted using an evaluation scale as well as a ranking test. In all the observed indicators, the commercial sample was evaluated the best. The cheese produced by combined curdling was received rather negatively due to the sour taste. The second-best cheese was ranked to be the cheese produced by acidic curdling. The results show that the acidic curdling is the best for taste as well as aromatic substance and fatty acid content. If we, however, consider other factors such as the time taken, the cheese produced by combined curdling appears to be the best overall.
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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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Characterization of lipids in fresh cheeses
Vaňková, Veronika ; Křikala, Jakub (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the determination of fatty acids in samples of fresh cheeses with or without the addition of plant extracts (rhyme, echinacea), produced in laboratory conditions at FCH BUT. The theoretical part of the thesis focuses on the general characterization of lipids and fatty acids. The next part discusses the characterization, division, and methods of cheese production, focusing mainly on fresh cheeses. The end of the work is devoted to gas chromatography as a method for the determination of fatty acids in cheese samples. The experimental part aimed to determine the content of fatty acids in the samples of fresh cheese. For the extraction of lipids from cheese samples, the choice of the method was according to ČSN EN ISO 1735. Acid esterification with boron trifluoride as a catalyst was used for the preparation of fatty acid methyl esters. The determination of fatty acid methyl esters was performed by gas chromatography with a flame ionization detector (FID). A total of 14 fatty acids were identified in all samples in a bound and free form. Myristric, palmitic, stearic and oleic acids predominated in all samples, which is in agreement with the knowledge of the composition of milk fat. The obtained results show, that even due to slight differences in the content of individual fatty acids, the addition of extracts does not affect the composition of fatty acids in fresh cheeses.
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Mikrobiologie sýrů ošetřených bioaktivními látkami za účelem prodloužení jejich trvanlivosti
Nedělová, Barbora
The theoretical part is focused on the production, distribution, and defects of cheese made from cow's milk, and its importance in nutrition. There are also described important species of beneficial and pathogenic microorganisms as well as the fight against undesirable microorganisms. In the last part of the literature review there are characteristics of selected groups of bioactive substances. The practical part of the thesis deals with analysis of microbiological fresh cheeses treated with natural substances due to their durability. Within microbiological analysis were determined selected groups of microorganisms - total number of microorganisms, lactic acid bacteria, psychrotrophic microorganisms, coliforms, enterococci, fungi and yeasts. Samples of fresh cheeses were treated with an extract of peppermint (Mentha piperita L.), mugwort tarragon (Artemisia dracunculus L.) and pumpkin seed oil. Subsequently, they were packed in an atmosphere free, containing CO2 or N2. The results showed that at a storage temperature of 8 ° C neither the used natural raw materials nor the atmosphere affects the shelf life of fresh cheeses.
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