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Influence of producing technology on flavour of Edam cheese
Urbanová, Andrea ; Buňka, František (referee) ; Vítová, Eva (advisor)
This work deals with the problem of flavour of Edam cheeses, i.e. natural hard cheese with low heat curd. The samples came from dairy MILTRA B s. r. o. Městečko Trnávka. A number of aroma active substances contribute to flavour of cheese. From the chemical point of view they are volatile compounds, including alcohols, aldehydes, ketones, fatty acids, esters, lactones, terpenes etc. Their content increases during ripening by influence of proteolytic and lipolytic changes and creates aroma, which is characteristic for type of cheese. The development of these components was monitored in chosen Edam cheese (30 % fat in dry matter) by headspace-SPME/GC method. The fiber CARTM/PDMS 85 µm was used for extraction of aroma compounds. The samples were taken from cheesemilk up to technologically ripe cheese. In total 30 aromatic compounds were identified, their content increased during ripening. The first increase was observed after pressing and then especially in second part of ripening. For comparison Edam cheese samples were also sensorially evaluated during ripening. The ordinal scale and profile tests were used for evaluation of organoleptic properties (appearance, texture, taste, aroma). The sensory quality was improved during ripening, but significant changes were not observed with regard to fine taste and smell of Edam cheese given by globally low content of aroma active compounds.
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Characterisation of processed cheese analoques
Svítilová, Lenka ; Horváthová, Viera (referee) ; Buňka, František (advisor)
The aim of this diploma work is to characterise processed cheeses and their analogues, to identify and quantify aroma active substances in the samples of cheese analogues, to evaluate their flavour using selected sensory methods and to compare the acquired results with the flavour of corresponding classic cheeses. The theoretical part is focused on general characteristic, classification, production technology of the processed cheeses and their analogues and on the list of aroma active substances occurring in cheeses. Furthermore, the summary of the methods suitable for sensory and analytic evaluation of cheese flavour and for the isolation of aroma active substances is given here. The samples of cheese analogues were made in Tomas Bata University in Zlín from coconut fat, butter, palm fat, milk fat and sunflower-seed oil. The classic processed cheeses were acquired commercially in the chain-store Billa. The aromatic substances were isolated and quantified using SPME-GC method, the fibre with the polar stationary phase CARTM/PDMS was used. Overall, 44 aroma substances were assessed: 9 aldehydes, 17 alcohols, 3 esters, 10 ketones and 5 acids. Classic processed cheeses contained the largest amount of aroma substances, Edam cheese, used for the production of cheese analogues, the smallest. Aroma compounds found in cheese analogues were then compared with raw materials used (Edam cheese and various fats), with the analogues produced last year and with classic processed cheeses. Finally, the results of the SPME-GC method and the sensory analysis were compared. It is possible to state that there are noticeable extensive differences between classic processed cheeses and cheese analogues, especially in taste.
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Composition of fatty acids in processed cheese analoques
Sůkalová, Kateřina ; Vespalcová, Milena (referee) ; Buňka,, František (advisor)
This thesis deals with the determination of fatty acids of processed cheese analogues. The aim is to identify and quantify the fatty acids in selected samples of cheese analogues. The introduction is a brief overview of the composition and properties of cheese analogues, technology and application options. The following describes the appropriate method for the determination of fatty acids in cheese and cheese analogues. Of these methods the largest part is devoted to gas chromatography, which is most frequently used method for detection of volatile fatty acids. Individual cheese analogues used for the analysis, contained various types of added fats. Specifically, the milk fat, coconut oil, sunflower oil, palm oil and butter. Samples of these fats were extracted and then converted to methylesters by methanol esterification with catalysis by potassium hydroxide. The most important fatty acids were identified and quantified in samples of cheese analogues using gas chromatography and compared with fatty acids of fats used for the preparation of these analogues are used.
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The factors influencing sensory quality of processed cheese analogues
Sůkalová, Kateřina ; Kráčmar, Stanislav (referee) ; Diviš, Pavel (referee) ; Buňka,, František (advisor)
The presented thesis deals with the monitoring sensory quality of processed cheese analogues, focusing mainly on the taste (flavour) and related content of volatile (aroma active) substances. Model samples of analogues were produced by a standard procedure at Tomas Bata University in Zlín. The experimental part was divided into two experiments, which differed in the composition of model samples of analogues. In the first experiment, the traditional fat (butter) was completely replaced by selected vegetable fats (palm, coconut, mixed), in the second experiment only a part (1% w/w - expressed on the total weight of the sample) of butter was replaced by vegetable oils (apricot, flax seed, currant, grape seed). Solid phase microextraction in conjunction with gas chromatography with flame ionization detection was used to determine volatiles. Methods based on valid international standards were used to evaluate the sensory quality of samples, focusing mainly on flavor, namely evaluation using scales (ISO 4121), profile test (EN ISO 13299) and ranking test (ISO 8587). The aim of the work was to assess the effect of the addition of various vegetable fats/oils on the above parameters, at the same time their changes were monitored during 6 months of storage (at 6 ° C). The results showed that the vegetable oil used affects both the sensory quality and the content and composition of volatile substances of analogues. Significant differences between samples were mainly in taste, aroma and overall acceptability. The decreasing overall acceptability of the samples can be expressed in experiment I by the order: product with butter coconut palm mixed fat; in the case of experiment II: product with butter apricot = flax = grape currant oil. Mixed fat, currant and grape seed oil proved to be unsuitable for the production of analogues, on the contrary, analogues with coconut fat and apricot oil were evaluated best. Based on the results of sensory analyses, it was shown that the samples maintain a good sensory quality min. for 3 months while maintaining a low storage temperature ( 6 ° C). An analogue with coconut fat, whose taste, aroma and acceptability were rated as very good, and apricot oil, whose taste, aroma and acceptability were even rated as excellent, could enrich the food offer on the market.
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Changes of sensory active substances during ripening of selected type of natural cheese
Sýkora, Michal ; Buňková, Leona (referee) ; Gregor,, Tomáš (referee) ; Buňka, František (advisor)
The presented dissertation is a study focused on the characterization of sensory quality, especially the flavour of model samples of natural cheeses. Attention is aimed to the composition and content of volatile (sensory active) substances as important markers of flavour and free/bound fatty acids as their precursors. The headspace solid phase microextraction in conjunction with gas chromatography with mass spectrometry was used to determine volatiles. For the determination of fatty acids, the lipids were isolated from the sample with a solvent mixture of diethyl ether and petroleum ether, followed by esterification using a methanolic solution of boron trifluoride as a catalyst and final analysis by gas chromatography with flame ionization detection. The experimental part was divided into two experiments; in experiment I, Moravský bochník type cheeses (45 % fat in dry matter., 60 % dry matter) were analysed, in experiment II, Edam type cheeses (45 % fat in dry matter, 50 % dry matter). Model samples of cheeses were made at Tomas Bata University in Zlín. For all samples, a classical mesophilic culture containing Lactococcus spp. and Leuconostoc spp. was used, this was always supplemented with a suitable monoculture of thermophilic bacteria; in the case of Moravský bochník cultures of Streptococcus thermophilus and Lactobacillus helveticus and in the case of Edam cheeses Lactobacillus casei and Lactobacillus plantarum. The essence of both experiments was to assess the influence of the used microbial cultures on the above-mentioned parameters, at the same time their changes during the ripening of the cheeses were monitored. The results showed that the addition of thermophilic cultures, as well as the maturation process did not affect the number of fatty acids or volatiles, but significant differences were found in their content. The content of bound fatty acids decreased during cheese ripening due to ongoing lipolytic changes while increasing the content of free fatty acids and their subsequent degradation to volatile substances, which ultimately contribute to the taste and aroma of the cheese. Ketones and acids were the most quantitatively present in all samples. During maturation, contrary to expectations, the content of identified volatiles also decreased. The addition of the thermophilic cultures didn’t have a clear effect and varied depending on the maturation phase. In the first phase, although they showed more pronounced lipolytic activity, the subsequent metabolic processes - the breakdown of free fatty acids into volatile substances, compensated for these differences. These results confirm a significant share of the basic mesophilic culture in the formation of volatile substances, in particular the flavour of cheeses.
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Monitoring of sensory active compounds during cheese production
Ryglová, Hana ; Buňka, František (referee) ; Vítová, Eva (advisor)
This work deals with monitoring of sensory active compounds during production of Edam cheeses, i.e. natural hard cheeses with low heat curd, and of processed cheeses, which were produced from Edam cheeses. Sensory active compounds contribute to overal flavour of cheese. They are volatile compounds, which include alcohols, aldehydes, ketones, fatty acids, esters, lactones, terpenes etc. These compounds were identified and quantified using SPME/GC/FID method in the model samples of Edam cheeses and processed cheeses, produced at Tomas Bata University in Zlin. In total 42 volatile compounds were identified, 6 aldehydes, 7 ketones, 15 alcohols, 6 esters and 8 acids. Differences in number of compounds identified, as well as in the contents of them, were found between samples. Effect of pasteurization on the contents and composition of the identified compounds was the most obvious in the samples of matured cheeses. In the samples of processed cheeses the effect of pasteurization was the most obvious in combination with prolonged heating during melting.
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Modern Approaches in Qualitative Aspects of Foods Assessment
Tobolková, Blanka ; Omelka, Ladislav (referee) ; Rapta, Peter (referee) ; Buňka, František (referee) ; Polovka, Martin (advisor)
Antioxidant properties and some other characteristics of selected organic and conventional products (wine, spelt flours) were evaluated in view of their potential utilization as markers suitable for food unambiguous differentiation according to the affiliation to production system. Beside these, study of fruit juices stability during storage in dependence on different technological procedures of juice processing was performed. In both cases, combination of dominantly EPR and UV/VIS spectroscopy but also other methods (e.g., HPLC, AAS, electrophoresis) was applied to evaluate the stability and antioxidant properties of selected samples. Statistical methods, especially methods of multivariate statistics were used to assess the influence of production and technological-processing operations on antioxidant status of foods and their selected characteristics. Qualitative analysis of Slovak and foreign organic and conventional wines proved that their antioxidant properties are influenced by production system, vintage and variety. On the basis of statistical analysis, descriptors of AAE, kTEMPOL and %RS were selected as the most powerful markers for Slovak organic and conventional wines discrimination. The discrimination of white and red organic and conventional wines possessed 100% and 95.2% correctness, respectively. High correctness of differentiation of Slovak and foreign wines was also achieved. Monitored descriptors of antioxidant activity of spelt flours varied in dependence on season, origin, variety, production system and depend also on way of spelt treatment, although this effect is not so significant. It was also confirmed that the type of extraction agent substantially affects the composition of extracts including polyphenols and flavonoids concentration, affecting thus also their antioxidant activity. Mixture of 50% ethanol/water was selected as the most promising extraction system. Although the results of individual spectroscopic assays revealed high variability and often ambiguous trends, the differences found were sufficient for successful differentiation of both wines and spelt flour samples according to the selected criteria by multivariate statistical processing of the data. Influence of changes in technological procedures of fruit juice processing (nitrogen atmosphere application, utilization of caps with oxygen scavengers) on radical-scavenging properties of 100% pineapples juices with pieces of pineapple and 100% orange juices with pulp was assessed as well. Results obtained proved that antioxidant activity of juices varied in dependence on storage conditions (temperature, storage time, light exposure) and depends also on origin, variety and quality of fruit used. However, the application of nitrogen atmosphere and active packaging materials is not sufficient enough to eliminate the oxidation reactions in juices, but changes in antioxidant activity are better predictable. It can be concluded that EPR spectroscopy could be effectively applied for wines and spelt flours differentiation according to the way of production and to assess the stability of food products, either alone or in combination of UV/VIS spectroscopy and the other methods, utilizing multivariate statistics for processing of experimental data.
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Elaboration and introduction of the method for determination of some proteins
Hruzík, Ondřej ; Buňka, František (referee) ; RNDr.Karel Gebauer (advisor)
Core protein of aggrecan has a significant share on the correct function of articular cartilage. Its lack or structural failure could be the reason for the disfunction of the cartilage. The culture of chondrocytes taken from a pork articular cartilage was used for the study of aggrecan production. The monolayer culture method offers the model system which has enabled us to watch the aggrecan production into growth medium. The aggrecan synthesis was stimulated in the media with addition of L-methionin, L-serin and sodium selenite pentahydrate. Methionin and serin are antecedents of sulphur amino acid of cysteine, whose role is incredibly important for the correct function of core protein. Growth media and chondrocytes were analysed with the help of the automatic amino acids analyzer unit after acid or oxidative hydrolysis. The analyse established the amino acid representation. The main attention was paid to cysteine. The changing concentrations of this amino acid were showing if the antecedents in the addition are used for its production and, therefore, if it is possible to stimulate the production of core protein with these antecedents. The results are discussed in the conclusion of this thesis. The next step should be the detection of the concentration of synthesized aggrecan by the immunological method. Presently this method is very expensive. Therefore, the method of setting the core protein of aggrecan with the help of suitable amino acid was used for the first tests.
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Risk Management of the Payment Process Optimization Project
Cebáková, Tereza ; Buňka, Antonín (referee) ; Doskočil, Radek (advisor)
This diploma thesis deals with the risk management in the payment process optimization project. To fulfill the main objective, the norm ČSN ISO 31000:2009 was followed. In the preparation phase for the analysis of the risks were used strategic, scheduling, resource, and cost analysis. Based on the results from these methods, the project risks were identified. Qualitative approach was used in the quantitative phase. Next, the corrective measures were suggested. In the last part, a process of risks monitoring is proposed.
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Risk Management of the Payment Process Optimization Project
Cebáková, Tereza ; Buňka, Antonín (referee) ; Doskočil, Radek (advisor)
This diploma thesis deals with the risk management in the payment process optimization project. To fulfill the main objective, the norm ČSN ISO 31000:2009 was followed. In the preparation phase for the analysis of the risks were used strategic, scheduling, resource, and cost analysis. Based on the results from these methods, the project risks were identified. Qualitative approach was used in the quantitative phase. Next, the corrective measures were suggested. In the last part, a process of risks monitoring is proposed.
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