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Assessment of fatty acids in processed cheese
Mitra, Michal ; Sýkora, Michal (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with determination of fatty acids in samples of processed cheeses made at Tomas Bata University in Zlín. In the theoretical part, lipids and fatty acids are characterized. Subsequently, the issue of production, distribution and composition of natural and processed cheeses is discussed. The conclusion of the theoretical part is focused on the assessment of fatty acids, i.e. their extraction and the determination by gas chromatography. In the experimental part, the fatty acid content of the seven samples of processed cheese was compared on the basis of different temperatures and the time of their production. The ČSN EN ISO 1735 method was used for extraction of fat. The method with methanolic potassium hydroxide solution was used for esterification. The determination of fatty acid methyl esters alone was accomplished by gas chromatography with a flame ionization detector. Based on the comparison with the standards, 17 fatty acids were identified in the samples.
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Assessment of fatty acids in processed cheese
Pruknerová, Kateřina ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This thesis is focused on determination of fatty acids in processed and/or processed cheese analogues using gas chromatography with FID detection. Characterization of fatty acids, various methods for lipid extraction and the possibilities of determination of fatty acids are described in the theoretical part. Simple and rapid method for the determination of fatty acids in natural and/or processed cheese was optimized and validated in the experimental part. The modified Folch method (by mixture of chloroform - methanol) was selected for lipid extraction from the samples. The standard method (ISO 5509), using a methanol solution of potassium hydroxide, was selected for lipid esterification. Type of the stationary phase and parameters of the column, flow of carrier gas, temperature of the injector, injection technique, temperature of the detector and temperature program were optimized. Calibration curves were constructed from five calibration points (in the concentration range of 0.01 - 60 g.ml-1), all correlation coefficients R2 were higher than 0,99. The limits of detection and quantification of individual fatty acids ranged from 0.002 - 6 g.ml-1. The repeatability of the method was good, all the relative standard deviations of the peaks were below 9 %. The optimized and validated method was applied to selected samples of processed cheese analogues. In total five types of analogues containing different kinds of fat (butter, apricot, linseed, black currant and grape seed oils) were analyzed. In samples 34 fatty acids were identified based on a comparison of retention times of standards.
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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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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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Mikrobiologie tavených sýrů
Košarišťanová, Ludmila
The aim of this bachelor thesis is on the microbiology of processed cheeses. Describing their microbiological quality and adverse contamination by microorganisms. The most contagious microorganisms are bacteria, creating disputes and microfungi. It defines its negative impact on quality of processed cheeses as well as it´s characterizing possible contaminants of processed chesses, which may cause alimentary disease in humans. The next part of the thesis is an experimental microbiological analysis of different processed cheese´s storage methods.
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Assessment of fatty acids in processed cheese
Mitra, Michal ; Sýkora, Michal (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with determination of fatty acids in samples of processed cheeses made at Tomas Bata University in Zlín. In the theoretical part, lipids and fatty acids are characterized. Subsequently, the issue of production, distribution and composition of natural and processed cheeses is discussed. The conclusion of the theoretical part is focused on the assessment of fatty acids, i.e. their extraction and the determination by gas chromatography. In the experimental part, the fatty acid content of the seven samples of processed cheese was compared on the basis of different temperatures and the time of their production. The ČSN EN ISO 1735 method was used for extraction of fat. The method with methanolic potassium hydroxide solution was used for esterification. The determination of fatty acid methyl esters alone was accomplished by gas chromatography with a flame ionization detector. Based on the comparison with the standards, 17 fatty acids were identified in the samples.
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Chování spotřebitele na trhu tavených sýrů v Jihomoravském kraji
Vágnerová, Michaela
This bachelor thesis deals with consumer behaviour on the processed cheese market in the South Moravian region. Marketing survey was conducted to determine key factor which influence consumer during shopping of processed cheese and during consumer select the shop, preferences of brand, price, packaging. Based on result of questionnaire survey recommendation are suggested for subjects which operate on this market.
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Assessment of fatty acids in processed cheese
Pruknerová, Kateřina ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This thesis is focused on determination of fatty acids in processed and/or processed cheese analogues using gas chromatography with FID detection. Characterization of fatty acids, various methods for lipid extraction and the possibilities of determination of fatty acids are described in the theoretical part. Simple and rapid method for the determination of fatty acids in natural and/or processed cheese was optimized and validated in the experimental part. The modified Folch method (by mixture of chloroform - methanol) was selected for lipid extraction from the samples. The standard method (ISO 5509), using a methanol solution of potassium hydroxide, was selected for lipid esterification. Type of the stationary phase and parameters of the column, flow of carrier gas, temperature of the injector, injection technique, temperature of the detector and temperature program were optimized. Calibration curves were constructed from five calibration points (in the concentration range of 0.01 - 60 g.ml-1), all correlation coefficients R2 were higher than 0,99. The limits of detection and quantification of individual fatty acids ranged from 0.002 - 6 g.ml-1. The repeatability of the method was good, all the relative standard deviations of the peaks were below 9 %. The optimized and validated method was applied to selected samples of processed cheese analogues. In total five types of analogues containing different kinds of fat (butter, apricot, linseed, black currant and grape seed oils) were analyzed. In samples 34 fatty acids were identified based on a comparison of retention times of standards.
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The effect of a storage conditions on aroma compounds in processed cheese
Štouračová, Anna ; Buňka, František (referee) ; Vítová, Eva (advisor)
The aim of this diploma thesis was to monitor influence of storage conditions (temperature and time) on content of aroma substances in sterilized processed cheeses and also on their flavour. The part of cheeses was stored at 6°C, second part at room temperature 23 °C and third part at 40 °C. Processed cheeses were produced by Madeta, a. s., sterilized at 117 °C 20 min. The analysis was made at regular intervals, cheeses stored 16 and 23 months were analysed in this work. The aroma compounds were isolated by SPME and subsequently identified and quantified by gas chromatography. In total 37 aroma compounds were identified and quantified, 7 aldehydes, 7 ketones, 6 acids, 12 alcohols and 5 esters. Total content of aroma compounds increases with higher storage temperature. The time of storage has also influence on content of aroma compounds, we may say, that content is increasing, although sharp growth was registered only after 23 months, namely in the thermostat. Simultaneously sensory analysis of cheeses was made. Ranking test and evaluation using scale were used. Cheeses from a fridge were always evaluated as the best in all categories. Cheeses stored at room temperature were evaluated worse and cheeses from thermostat were the worst. So it is apparent, that high temperature supports undesirable chemical changes in cheeses and certainly is related to their flavour.
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The effect of a storage conditions on fatty acids in processed cheese
Němcová, Tereza ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the changes in content of fatty acids in long-lasting stored sterilized processed cheeses. Cheeses were stored under different temperatures 6 ± 2 °C, 23 ± 2 °C and 40 ± 2 °C during 23 months. Measurements was made in 16th and 23rd month of storage. The samples of sterilized processed cheeses were extracted by using mixture of solvents (ethanol, diethylether and petrolether). The obtained fat was then saponified by methanolic solution of potassium hydroxide. The methylesthers were analyzed by gas chromatography with flame ionization detection. Lauric, myristic, palmitic, oleic and stearic acids were the most abundant in cheeses. The yield was measured in these main acids. To summarize the content of fatty acids decreased during time of storage and also by influence of storage temperature higher than in refrigerator.
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