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Výzkum spolehlivosti pájených spojů v dusíkové atmosféře
Vala, Martin ; Adámek, Martin (oponent) ; Szendiuch, Ivan (vedoucí práce)
Tato práce zkoumá vliv dusíkové atmosféry na kvalitu pájeného spoje bezolovnatými pájecími pastami. Pro pájecí pasty se změřily a nastavily teplotní profily. Součástí je realizace a měření vzorků v ochranné dusíkové atmosféře s různou koncentrací zbytkového kyslíku a bez ochranné atmosféry. Tato měření se porovnala a vyvodil se závěr vlivu dusíkové atmosféry. Byla zkoumána spolehlivost a jakost pájeného spoje.
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Study of qualitative parameters of fruit juices and possibilities of their modification via technological modifications
Fajtl, Zdeněk ; Omelka, Ladislav (oponent) ; Polovka, Martin (vedoucí práce)
Fruit juices belong to the most popular drinks worldwide. Besides vitamins and minerals they represent rich source of phenolic compounds recognized for their antioxidant activity. Increasing consumer’s demands towards high quality and safe food products push their producers to increase the production and qualitative standards of the products. Recent innovations in juices production resulted in modification of production conditions, comprising the modification of composition (e.g., addition of fruit pulp and/or small fruit pieces) innovations in packaging materials and the production atmosphere modification. In the diploma thesis, the effects of production conditions of fresh orange juices with pulp and pineapple juices and their modification, as well as the effect of conditions of their long-term storage on selected qualitative characteristics (antioxidant activity, color changes and concentration of selected phytochemicals) are assessed and evaluated dominantly by EPR and UV-VIS spectroscopy. Results obtained were processed by multivariate statistics in order to evaluate the effects of sample origin and season or production technology on the monitored characteristics and overall quality of fruit juices. Results obtained indicated that pasteurization influence the quality of the product, although the slight pasteurization was applied, as in comparison to the fresh – non-pasteurized samples, slight decrease of values of the monitored parameters was observed. However, as regards the post-pasteurization changes, significant influence of the production atmosphere on the monitored qualitative parameters of juices was noticed, proving that replacement of oxygen by inert gases prolongs significantly the juices shelf live. Kinetic study of the changes of the monitored parameters upon the storage period indicate that in majority of cases, gradual worsening of all the monitored parameters was observed, without respect on technology of juice processing. In the samples processed under the modified atmosphere, generally the retardation of the decrease as a result of inert atmosphere application in dependence on type of production gas was noticed. This trend was particularly obvious for longer storage periods, whereas in the beginning of storage (6 - 7 weeks after production), the observed trends were unambiguous. Thus, it can be supposed that this “protecting” effect of inert atmosphere is influenced by the physico-chemical properties of gases, mostly by their solubility in the liquid juice medium. It was also proved, that the properties of juices, are significantly affected by the effects of season and raw juice origin. As follows from the results of statistical analysis, the year of production is strong discriminant factor as on the basis of all the monitored characteristics, absolute discrimination of the samples by canonical discrimination analysis was achieved. As regards raw material origin, only partial differentiation, although with high classification score was obtained. As regards the effect of production technology, the partially successful differentiation of samples according to the inert gas applied was obtained. The obtained results will help the juice producer in optimization of the juice production conditions in order to obtain the product with maximum beneficial properties kept during the whole expiration period. Its length can also be optimized on the basis of the presented results.
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Testování vlastností pájek v ochranné atmosféře
Vala, Radek ; Jankovský, Jaroslav (oponent) ; Szendiuch, Ivan (vedoucí práce)
Projekt řeší návrh a celkovou konstrukci zařízení nazývané exsikátor pro pájení v ochranné atmosféře. Pro zařízení bylo navrhnuto a vyrobeno chlazení a topný element. Pro pájení byly nadefinovány pájecí profily pro bezolovnaté a olovnaté pájky. Proběhla realizace vzorků, které byly proměřeny a analyzovány. Na závěr byly vytvořeny mikrovýbrusy pro bezolovnatou pájku.
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Investigation Of Influence Nitrogen Atmosphere On The Spreadability And Reliability Of Solder Joints
Vala, Martin
This article examines the impact of nitrogen atmosphere on the quality of the solder joint. For tests were used two lead-free solder pastes, specifically SAC305 and SN100C. These pastes were printed on a substrate FR4 with ENIG finish with semiautomatic devices. For reflow of paste was used specially modified desiccator. This device has hot plate with the cooling system. This system is active after reflow. In this device, it was possible to create around the solder paste a nitrogen atmosphere having defined content of residual oxygen. This experiment determined the most appropriate concentration of the protective gas atmosphere to obtain the greatest wettability and spreadability of paste, which is a prerequisite for a good solder joint.
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Výzkum spolehlivosti pájených spojů v dusíkové atmosféře
Vala, Martin ; Adámek, Martin (oponent) ; Szendiuch, Ivan (vedoucí práce)
Tato práce zkoumá vliv dusíkové atmosféry na kvalitu pájeného spoje bezolovnatými pájecími pastami. Pro pájecí pasty se změřily a nastavily teplotní profily. Součástí je realizace a měření vzorků v ochranné dusíkové atmosféře s různou koncentrací zbytkového kyslíku a bez ochranné atmosféry. Tato měření se porovnala a vyvodil se závěr vlivu dusíkové atmosféry. Byla zkoumána spolehlivost a jakost pájeného spoje.
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Testování vlastností pájek v ochranné atmosféře
Vala, Radek ; Jankovský, Jaroslav (oponent) ; Szendiuch, Ivan (vedoucí práce)
Projekt řeší návrh a celkovou konstrukci zařízení nazývané exsikátor pro pájení v ochranné atmosféře. Pro zařízení bylo navrhnuto a vyrobeno chlazení a topný element. Pro pájení byly nadefinovány pájecí profily pro bezolovnaté a olovnaté pájky. Proběhla realizace vzorků, které byly proměřeny a analyzovány. Na závěr byly vytvořeny mikrovýbrusy pro bezolovnatou pájku.
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Study of qualitative parameters of fruit juices and possibilities of their modification via technological modifications
Fajtl, Zdeněk ; Omelka, Ladislav (oponent) ; Polovka, Martin (vedoucí práce)
Fruit juices belong to the most popular drinks worldwide. Besides vitamins and minerals they represent rich source of phenolic compounds recognized for their antioxidant activity. Increasing consumer’s demands towards high quality and safe food products push their producers to increase the production and qualitative standards of the products. Recent innovations in juices production resulted in modification of production conditions, comprising the modification of composition (e.g., addition of fruit pulp and/or small fruit pieces) innovations in packaging materials and the production atmosphere modification. In the diploma thesis, the effects of production conditions of fresh orange juices with pulp and pineapple juices and their modification, as well as the effect of conditions of their long-term storage on selected qualitative characteristics (antioxidant activity, color changes and concentration of selected phytochemicals) are assessed and evaluated dominantly by EPR and UV-VIS spectroscopy. Results obtained were processed by multivariate statistics in order to evaluate the effects of sample origin and season or production technology on the monitored characteristics and overall quality of fruit juices. Results obtained indicated that pasteurization influence the quality of the product, although the slight pasteurization was applied, as in comparison to the fresh – non-pasteurized samples, slight decrease of values of the monitored parameters was observed. However, as regards the post-pasteurization changes, significant influence of the production atmosphere on the monitored qualitative parameters of juices was noticed, proving that replacement of oxygen by inert gases prolongs significantly the juices shelf live. Kinetic study of the changes of the monitored parameters upon the storage period indicate that in majority of cases, gradual worsening of all the monitored parameters was observed, without respect on technology of juice processing. In the samples processed under the modified atmosphere, generally the retardation of the decrease as a result of inert atmosphere application in dependence on type of production gas was noticed. This trend was particularly obvious for longer storage periods, whereas in the beginning of storage (6 - 7 weeks after production), the observed trends were unambiguous. Thus, it can be supposed that this “protecting” effect of inert atmosphere is influenced by the physico-chemical properties of gases, mostly by their solubility in the liquid juice medium. It was also proved, that the properties of juices, are significantly affected by the effects of season and raw juice origin. As follows from the results of statistical analysis, the year of production is strong discriminant factor as on the basis of all the monitored characteristics, absolute discrimination of the samples by canonical discrimination analysis was achieved. As regards raw material origin, only partial differentiation, although with high classification score was obtained. As regards the effect of production technology, the partially successful differentiation of samples according to the inert gas applied was obtained. The obtained results will help the juice producer in optimization of the juice production conditions in order to obtain the product with maximum beneficial properties kept during the whole expiration period. Its length can also be optimized on the basis of the presented results.
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Vliv technologie balení na trvanlivost produktů
RYKROVÁ, Lucie
Mikrobiologická kvalita potravin je důležitá jak z důvodu hygienického, tak zdravotního a má nemalý vliv na údržnost potravin. Cílem této diplomové práce bylo zhodnotit vzorky masných výrobků z hlediska kontaminace mikroorganismy. K dispozici byl měkký masný výrobek, výrobek tepelně opracovaný a tepelně neopracovaný. Hodnotilo se jak ovlivní nakrájení výrobku a následné zabalení do vakua celkový počet mikroorganismů, dále vliv teploty okolí na rozvoj bakterií a zda výroba pomocí nové technologie prospěje hygienické jakosti výrobku. Jak vyplynulo z výsledků, tyčový výrobek vykazoval mikroorganismů méně, než výrobek, který byl nakrájen a poté zabalen do vakua. Na vině bylo zřejmě nářezové zařízení, které nebylo dokonale dezinfikováno a došlo k přenosu bakterií. Tudíž je nutno zvýšit hygienická opatření a dohlédnout na jejich důsledné dodržování. Projevil se i vliv teploty na růst mikroorganismů. Při rostoucí teplotě se zvyšoval i počet mikroorganismů. Užití klimatizovaných komor při výrobě masných výrobků se ukázalo z hlediska snížení celkového počtu mikroorganismů jako příznivé.
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