Dissertationen zum Thema „Uljens“
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Haugen, Ulrika, und Susanne Lidzén. „Distansundervisning på mellanstadiet under coronapandemins första våg : Lärares relationella och didaktiska val vid distansundervisning i ämnesspecifik läsförståelse i naturorienterande ämnen“. Thesis, Uppsala universitet, Institutionen för pedagogik, didaktik och utbildningsstudier, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-446402.
Der volle Inhalt der QuelleAbstract The Covid-19 (Corona) pandemic struck in the spring of 2020, creating concern and anxiety amongst the population at large and in schools especially. The authorities decided at a national level that primary schools should remain open and that education should continue as usual, as opposed to teaching remotely via digital media. Despite this directive, teachers at the local level acted differently, making their own decisions or following those of their local principals. The purpose of this study, which is based on reflective school didactic theory (Uljens, 2011) and relational theory (Aspelin, 2018) is to investigate and broaden our knowledge of how middle school teachers in science subjects described how they taught students who remained at home in subject specific reading comprehension. The study also examines how they maintained their relationship with students at home during the spring of 2020 from a school didactic and relational perspective. Nine middle school science teachers were interviewed individually following a qualitative, semi-structured form of interviews. The analysis reflects a realistic interpretation (Kvale & Brinkmann, 2020) of the teachers’ accounts as to how they had taught remotely, and the analysis of the empiric material was based on the study’s three research questions: interpretation of national directives, didactic choices and maintaining relationships. The results of the study revealed considerable variation in the respondents’ answers to all research questions. The study’s main contribution to previous research illustrates how teachers interpreted directives from the state at the national level in different ways. The study also shows that different ways of teaching science subjects and supporting students’ subject specific reading comprehension can be challenging when teaching remotely. Consequently, the teacher’s didactic choice, the teachings what, how and who/which in remote teaching can be decisive. Most of the teachers interviewed for the study experienced challenges in maintaining relationships. However, the study concluded that in cases where teachers had interactive meetings via digital video channels, they found it was possible to create a personal contact and relate to the students who could see and be seen on an emotional as well as educational level. As the study focused on an unexplored field at the national level, further research into the didactic and relational choices that teachers made during the first wave of the pandemic in the spring of 2020 is of the utmost importance, so that in the event of further waves of the virus, teachers will be able to maintain their relations with students and at the same time provide the same teaching experience for subject-specific reading comprehension and any special needs support whether the students are at home or at school.
Dušica, Jovičić. „Antioksidativni kapacitet, tolerantnost na oksidativni stres i životna sposobnost uljane repice“. Phd thesis, Univerzitet u Novom Sadu, Poljoprivredni fakultet u Novom Sadu, 2014. https://www.cris.uns.ac.rs/record.jsf?recordId=85852&source=NDLTD&language=en.
Der volle Inhalt der QuelleIZ
Visoke koncentracije soli u zemljištu dovode do oksidativnog stresa u biljkama usled narušavanja procesa transporta elektrona u pojedinim ćelijskim organelama i nastajanja velike količine toksičnih oblika kiseonika kao što su superoksid-radikal, hidroksi-radikal, vodonik-peroksid i singlet kiseonik. Kako bi neutralisale štetne efekte reaktivnih kiseoničnih vrsta, biljke su razvile mehanizme odbrane poznate kao antioksidativni sistemi koji regulišu količinu navedenih toksičnih vrsta u zavisnosti od potreba. Osnovni cilj ovog istraživanja je bio da se utvrde razlike u biohemijskim i fiziološkim odbrambenim mehanizmima između različitih genotipova uljane repice u uslovima zaslanjenosti, kao i definisanje parametara antioksidativnog statusa koji ukazuju na povećanu tolerantnost ove vrste na veću količinu soli. U radu su prikazani rezultati ispitivanja uticaja različitih koncentracija NaCl (100 mmol/l, 150 mmol/l, 200 mmol/l) na antioksidativne osobine i parametre oksidativnog stresa u početnim fazama razvoja četiri genotipa uljane repice. Takođe, antioksidativni status određen je i u biljkama uljane repice gajene u polukontrolisanim uslovima na tri tipa zimljišta (černozem, solonjec, solončak). Merene su aktivnosti antioksidativnih enzima (SOD, GPx), intenzitet lipidne peroksidacije, količina redukovanog glutationa, kapacitet skevindžer aktivnosti hidroksi-radikala, ukupna antioksidativna aktivnost FRAP metodom i DPPH - skevindžer aktivnosti. Ispitana je i životna sposobnost semena uljane repice u uslovima zaslanjenosti i određeni su klijavost semena i parametri porasta primenom različitih vigor testova. Antioksidativni status u semenu i poniku, kao i životna sposobnost semena ispitani su u godini proizvodnje semena i nakon godinu dana čuvanja u nekontrolisanim uslovima. Dobijeni rezultati ukazuju da postoje jasne razlike između ispitivanih genotipova kada se posmatra aktivnost antioksidativnih enzima (SOD, GPx), neenzimskih antioksidanata (GSH) i intenzitet lipidne peroksidacije kako u nadzemnom delu tako i u korenu. U prvoj godini antioksidativni enzimi su bili aktivniji kada su predstavljali osnovu antioksidativnog zaštitnog sistema, dok su u drugoj godini ispititivanja ovu ulogu
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preuzeli neenzimski antioksidanti. Razlog za ovo je to što enzimi nakon godinu dana čuvanja semena gube aktivnost. Ogled u polukontrolisanim uslovima na različitim tipovima zemljišta ukazivao je da je aktivnost svih ispitivanih parametra antioksdantnog statusa na oba tipa zemljišta bila najveća u fazi nakon zimskog mirovanja jer su biljke, pored sonog stresa, bile izložene i niskim temperaturama. Ispitivanje životne sposobnosti semena u zaslanjenim uslovima pokazalo je da je seme nakon godinu dana čuvanja zadržalo visok stepen fiziološkog kvaliteta samo ukoliko su uslovi za klijanje bili optimalni, dok je pri nastupanju stresnih uslova (već pri najmanjoj kocentraciji NaCl), uočeno značajno smanjenje procenta klijavosti. Rezultati dobijeni ovim istraživanjem se mogu se koristiti kao pokazatelji korisni za izbor tolerantnih genotipova uljane repice u uslovima zaslanjenosti.
Kruschinski, Henrike-Uljane [Verfasser]. „Biogasanlagen als Rechtsproblem : Errichtung und wirtschaftlicher Betrieb als Beitrag zu einer nachhaltigen Energieversorgung / Henrike-Uljane Kruschinski“. Aachen : Shaker, 2010. http://d-nb.info/1098042611/34.
Der volle Inhalt der QuelleVesna, Vujasinović. „Uticaj termičke obrade na nutritivnu vrednost i oksidativnu stabilnost ulja semena uljane tikve golice Cucurbita pepoL“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2011. http://dx.doi.org/10.2298/NS20110927VUJASINOVIC.
Der volle Inhalt der QuellePumpkin seed oil is one of the specialty oils produced only by mechanical procedure and can be classified in the group of functional food products. This oil is very attractive (interesting) for the consumers first of all for its characteristic flavour, high nutritive value and proved beneficial effect on health. The aim of the investigations in the scope of this thesis was to characterize the sensoric-nutritive quality and oxidative stability of cold pressed and virgin pumpkin seed oils from the market, to investigate the effect (influence) of heat treatment of seed on quality, nutritive value and stability of virgin pumpkin seed oil and to define the sensory characteristics and stability of cold pressed pumpkin seed oil. Aiming to characterize the oil, a number of cold pressed and virgin pumpkin seed oil samples, randomly taken from the domestic and foreign market, were investigated (analyzed). The basic characteristics and most important qualitative differences between these two categories of oils produced applying different technologies were defined. Both types of pumpkin seed oils are produced from the same raw material, however, they differ significantly regarding a number of quality, and expecially sensory proterties (taste, odour, flavour and colour), so the consumers may become embarrassed. Investigating the influence of different heat treatment of seed, it was found that the roasting of ground material before the pressing affects significantly the quality characteristics and stability of virgin oil. The heat treatment of ground seed at temperatures 90 to 130 °C, for 30 to 70 min, showed different influence on sensory quality, content of bioactive components and oxidative stability of oil, exhibiting both negative and positive effect. In the part dealing with the defining of sensory characteristics and stability determination of oil obtained by cold pressure of dried pumpkin seed on screw press, it was found that most quality oil was obtained by the first pressing process, the oil flavur is the best, with lowest acid and peroxide value, and the induction period is the longest. This was confirmed by pressing both hull-less pumpkin and hull-less with the addition of pumpkin seed with hull. The most important characteristics for oil stability were followed for two years. In this period a certain deterioration of sensory quality was found, the acid and peroxide value increased, and the induction period decreased. However, disregarding the intensity of changes, the oil samples are in accordance with all legal quality normatives even after two years from the production date. However, in order to maintain the high (first-class) quality of cold pressed oil of hull-less pumpkin seed, the recomended period for the shelf-life of oil is one year.
Ivana, Nikolić. „Fizičke i senzorske karakteristike funkcionalnih prehrambenih namaza na bazi celuloznih hidrokoloida i brašna pogače uljane tikve“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2015. https://www.cris.uns.ac.rs/record.jsf?recordId=95367&source=NDLTD&language=en.
Der volle Inhalt der QuelleThe main objective of this study was to determine the possibility of production the low-fat functional food spreads based on flour of pumpkin seed and carbohydratehydrocolloids.That included complete characterization of components of the spreads, the flour of hull–less pumpkin seed and fiber based food hydrocolloids. Flour of pumpkin seed was analyzed in order to determine its physico–chemical characteristics, functional characteristics, microbiological safety and microstructural nature. These analyses of flour defined the physical, nutritional and microbiological characteristics and behavior of flour, with the aim of determine the possibilities of its application in further work.Also, two types of carbohydrate based hydrocolloids were examined by microstructural aspect, by particle size distribution, rheological determinations and textural characterization. The aim of these analysis was to define the type and concentration of fibers in the gel structure of hydrocolloids, which has the ability of to flour carrier and the role of continuous phase in the spread. This predictedthe behavior of carbohydrate based hydrocolloids in the food system such as spreads.The determination of main components of the spreads was followed by determination of optimal properties of the spreads, which included analysis of spreads with different type and concentrations of fibers in the gel system and thedifferent amount of the applied hydrocolloid. To determine the significance of the influence of variable factors on the properties of the obtained spreads, the method of design of experiment (DOE) was used, with applied full factorial design. Also, correlation between certain sensory and instrumentally determined parameters was defined.The aim of all analysis was to define the composition of the spread with optimal properties and to formulate the low–fat food spread based on flour of pumpkin seedBased on the results obtained within this doctoral thesis, it was concluded that the flour of pumpkin seed cake is nutritionally and biologically very valuable raw materialwith good sustainability, without pathogenic microorganisms, thus it is a suitable raw material for the production of spread. Also, Vivapur MCG 611F was characterized as hydrocolloid with better rheological and textural properties than the hydrocolloid Vitacel WFG HS73, because of its thixotropic flow properties, higher degree ofnetworking and pronounced elastic nature of structure that provides lower susceptibility to deformation and makes it suitable for the production of spread.Based on the influence of variable factors, related to the composition of spreads, it was concluded that the observed spreads were real rheological systems and that thecomposition of spreads signifficantly influenced on their rheological, textural and sensory characteristics. Obtained resultes of this research suggested that the production of low–fat food spread based on flour of pumpkin seed is possible. This spread contains 80% of MCG 611F fiber based hydrocolloid ( on the mass of the spread) with gel concentration of 7% and 20% of flour of pumpkin seed cake ( on the mass of the spread). The spread with optimal properties is poydisperse system with compact structure in which the flour particles are incorporated into continious network of hydrated MCG fibers and completly coated with avaliable amount of fat relacer. Due to this organization and structure of the system, optimal spread exhibits good properties for manipulation during production and application, such as good rheological characteristics, optimal spreadability and good adhesion to the surface. Obtained spread is nutritionaly valuable food product which can be classified into functional food product based on the composition and health inffluance.
Olgica, Radočaj. „Optimizacija tehnološkog procesa proizvodnje namaza sa visokim sadržajem omega masnih kiselina upotrebom pogače semena uljane tikve golice“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2011. http://dx.doi.org/10.2298/NS20110919RADOCAJ.
Der volle Inhalt der QuelleThe goal of this research was to investigate the possible use of hull-less pumpkin seed oil press cake, a by-product of the pumpkin seed oil pressing process, for the manufacturing of a spread. The spread would be similar to a peanut butter, in appearance, texture and rheological stability. Spreads were formulated in such way that they would have pleasant sensory attributes, good oxidative stability with a high omega-6 and omega-3 fatty acids content, while providing their balanced ratio based on modern healthy food principles as recommended by nutritionists. Optimization of the spread manufacturing technology was conducted based on the results of the two factorial experimental design on five levels using response surface methodology and statistical analysis (ANOVA). Desirable functional characteristics of the spreads were defined based on nutritional and textural attributes. Results have shown that pumpkin seed oil press cake (per 100 g) is very rich in minerals, especially phosphorus iron, magnesium and zinc that exceeds recommended daily intake (Pravilnik, 2004) over 100%. In addition, it contains high amounts of manganese, potassium and copper, which justifies the use of the seed oil press cake for investigation of the possibility for its use in nutritious spread manufacturing. Cold pressed hull-less pumpkin oil significantly contributed to the nutritional value of the spreads, since it is rich in omega-6 fatty acids (51.04%) and γ-tocopherols (704 mg/kg). Hemp oil had a significant effect on the sensory evaluation of the spreads, primarily on the taste and texture, as well as the oxidative stability of the spreads. It was confirmed that the shelf life of the spreads depended on the oxidation of the oils present in the spread, and primarily depended on the hemp oil quantity and quality. All spreads had a shelf life of maximum 6 months at ambient temperature. It was also confirmed that oil separation on the spreads’ surface depended on the amount of added stabilizer, where the best results were achieved with the addition of 1.6% stabilizer. Considering nutritional value, sensory evaluation, oxidative stability and texture, the optimal spreads were made using the stabilizer at 1.2-1.4% and hemp oil at 40-60% added to the fatty phaze of the spread. All prepared spreads contained omega-3 essential fatty acid that could be declared as a “source of omega-3 polyunsaturated fatty acids“. Few samples had a very high content of omega-3 fatty acids (0.98 and 1.24 g) per serving size 15 g). In addition, all prepared spreads contained omega-6 fatty acids, where some samples had a high content of omega-6 fatty acids per serving size (2.5-3 g), and could be declared as a “source of omega-6 polyunsaturated fatty acids“. All prepared spreads (except one) had a well balanced ratio between omega-6 and omega-3 fatty acids (2-3:1).
Biljana, Rabrenović. „Uticaj fizičko-hemijskih karakteristika semena uljane tikve (Cucurbita pepo L.) na kvalitet i nutritivna svojstva hladno presovanog ulja“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2012. https://www.cris.uns.ac.rs/record.jsf?recordId=76895&source=NDLTD&language=en.
Der volle Inhalt der QuelleCold-pressed pumpkin oil is a product specific to Serbia, given that other countries in the region traditionally produce virgin pumpkin oil. In the process of cold pressing raw-dried pumpkin seeds by screw press, the temperature of extracted oil does not exceed 50oC, which affects physical, chemical, nutritional and sensory characteristics of this oil, as well as its oxidative stability and antiradical capacity. For the purpose of more precise characterization of this product in the domestic market, the quality of cold pressed oil from seeds of many free breeding varieties and F1 hybrids – of both naked and husk seed pumpkins being grown in our country – was examined. Specific sensorial properties: light brown to reddish color, mild aroma, a smell similar to that of raw pumpkin seeds and a taste resembling that of pumpkin pulp are characteristic for this oil. As for sensory characteristics, the samples of oil from Austrian hybrid seeds, stood out. On the basis of fatty acid content, this oil belongs to the oleic-linoleic type, meaning it is a highly nutritional vegetable oil, which is also due to high levels of dominant gamma-tocopherol. Determination of the types and content of sterols was particularly important, given that there are no data specific to cold-pressed pumpkin oil in the literature. Delta-7 sterols are the most dominant sterols in examined oil samples and also very high content of squalene was found, which a compound with an important biological function is. The oil has an excellent antiradical capacity, showing a strong linear correlation with the amounts of phenolic compounds. Oil extracted from the cake, left over after the cold pressing of pumpkin seeds, had greater antiradical capacity than the samples of cold pressed oil, due to higher percentage of phenolic compounds and a slightly lower content of tocopherols compared to cold pressed oil.
Mauerere, Uljana [Verfasser], und Walter [Akademischer Betreuer] Koschmal. „K vozroždeniju Pravoslavija v Rossii: avtor i čitatel' sovremennych russkich žitij svjatych (1988-2015) / Uljana Mauerere ; Betreuer: Walter Koschmal“. Regensburg : Universitätsbibliothek Regensburg, 2020. http://d-nb.info/121748132X/34.
Der volle Inhalt der QuelleArpad, Kiralj. „Simultani uticaj energije površine vlakana, geometrije sloja i prirode uljne faze na obradu zauljenih voda koalescentnom filtracijom“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2017. http://www.cris.uns.ac.rs/record.jsf?recordId=102460&source=NDLTD&language=en.
Der volle Inhalt der QuelleThe aim of the doctoral thesis was to investigate the possibility of the stainlesssteel fibers application for the coalescence of mineral oil drops with differentpolarity varying also the bed permeability. Additional aim was the comparativeanalysis of the tested oil separation efficiency with fibers that have highand low surface energy. The method for the evaluation of the fiber-liquid wettingkinetic was set up and modified in order to assess the affinity of oil to theselected fiber that was used to form the filtration bed. For the first time, themethod of artificial neural networks was applied to simulate the coalescencefiltration.Experimental program of coalescence filtration was performed on oil-in-watermodel emulsion with constant inlet concentration of 500 mg/l, at a constanttemperature of 20°C, horizontal fluid flow orientation and average oil dropsize of 10 μm. The influence of bed geometry was studied varying bed permeabilityin the range from 0,1810-9 m2 to 5,51010-9 m2 for the constant layer thickness of 5 cm. Three samples of mineral oil that have large range of viscosityand polarity were tested. All experiments were carried out at constantfluid velocity in the range from 10 m/h to 80 m/h. The output dispersed phaseconcentration was determined by FTIR spectrophotometry.A significant contribution to the research of the coalescence phenomenon ina fiber bed was achieved by determining the possibility to use stainless steelfibers for the separation of mineral oil drops, broadening the apprehensionof the simultaneous influence of surface energy, bed geometry and oil phasenature, as well as the introduction of an iso-output concentration as a newparameter. The evaluation of the fiber-liquid wetting kinetic showed that thelipophilic-lyophobic wettability ratio of the material adequately describes thetendency of a filter material for the mineral oil separation. Such comprehensiveanalysis of the various parameters impact on the efficiency of coalescencefiltration, presented in this thesis, was not found in available literature. The resultsof the doctoral thesis will enable the reduction of time and material costneeded for the design of coalescer, by decreasing the extent of experimentalresearch necessary for successful design.Selected working conditions, primarily the fiber diameter in relation to the inputdrop size, as well as bed packaging, while ensuring the known and definedbed permeability, provided the desired separation, with the oil drop separationefficiency of tested stainless steel fibers in the range from 91% to 99% for a fluidvelocity range from 10 m/h to 50 m/h. When stainless steel was used, moreefficient separation was observed for the low bed permeability, whereas forthe polymer fibers the reverse order was identified. It was concluded that, inthe existing circumstances, different mechanisms of oil drop coalescence dominatefor these materials. The dependence of output concentration from thevelocity and bed permeability for both tested materials, stainless steel and polypropylene, was similar. Polypropylene has a higher operating velocity rangein comparison to stainless steel. However, when compared to polypropylene,stainless steel separates more successfully the oil with the lowest viscosity inthe low bed permeability and at low fluid velocity domain. Satisfactory qualityof separation with polypropylene is achieved at the highest bed permeabilityand in a wide fluid velocity range, whereas, with the stainless steel, the highestvalues of critical velocity, for the entire range of tested viscosity, are realized atthe lowest bed permeability.
Srđan, Sokolović. „Istovremeni uticaj permeabilnosti sloja, prečnika vlakna i ulazne koncentracije uljne faze na separaciju mineralnih ulja iz otpadnih voda“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2020. https://www.cris.uns.ac.rs/record.jsf?recordId=114057&source=NDLTD&language=en.
Der volle Inhalt der QuelleThe aim of this doctoral dissertation is to contribute to the study of insufficiently known phenomena of coalescent filtration, in order to reduce the number of pilot plant experiments required for designing filters for some specific applications. All the used materials are waste materials the use of which as a filter media contributes to sustainable development. One of the goals of this doctoral dissertation is to study the simultaneous effect of changes in bed permeability and fiber thickness on bed properties, pressure drop and the efficiency of the dispersed oil separation from a continuous aqueous phase. The effect of bed geometry was studied by applying the beds of homogeneous and heterogeneous geometry in depth. A detailed examination of the appearance and morphology of the fibers, as well as the structure of the bed and the appearance and arrangement of its pores, was performed by scanning electron microscopy and optical microscopy. The doctoral dissertation gives an overview of the testing of fibers of different nature (free and interconnected, rigid and elastic, of different thickness and thus of different meandering) and their beds. The simultaneous effect of the changes in the input dispersed phase concentration and the bed permeability was also investigated. Much of the conducted research includes the study of the impact of the nature of the oil phase, and it is necessary to point out that all used oils are mineral oils. The goal of optimizing the operation of a coalescer was to find the conditions providing the maximum critical velocity value with a minimum pressure drop.
Lutz, Matthias Uljas [Verfasser], und Rüdiger [Akademischer Betreuer] Klingeler. „A Magnetic Force Microscopy Investigation of alpha-Fe, Fe3C and Permalloy Nanowires under Applied Magnetic Fields / Matthias Uljas Lutz ; Betreuer: Rüdiger Klingeler“. Heidelberg : Universitätsbibliothek Heidelberg, 2012. http://d-nb.info/117780901X/34.
Der volle Inhalt der QuelleVera, Krimer Malešević. „Fenolni potencijal uljanih pogača“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2016. http://www.cris.uns.ac.rs/record.jsf?recordId=101055&source=NDLTD&language=en.
Der volle Inhalt der QuelleWithin the thesis, the possibility of by-products (formed during the process of cold oil pressing) exploitation as a source of natural phenolic acids was examined. Selection of the samples included pumpkin, black cumin, flax and pomegranate. For the purpose of bonded phenolic acids release and for the total phenolic acids content and distribution (in the solid samples) assessment, the alkaline hydrolysis with the addition of L-ascorbic acid and EDTA was employed. The results show that all analyzed cakes can be used to obtain valuable phenolic acids, while the distribution of phenolic acids depends on the type of oil cakes. The concentration of free phenolic acids proved to be significant for a pumpkin oil cake, ester for pomegranate and flax oil cakes, and insoluble-bound for black cumin and pomegranate oil cakes. Of all analyzed samples, pomegranate hull contains the highest content of ester-linked phenolic acids, due to a very high content of gallic acid. After phenolic acids determination in the by-products, principal components analysis (PCA) allowed the separation of plant samples in groups according to origin and reduced the number of phenolic acids necessary for their characterization, which may have potential application in the screening of phenolic acids and determining the quality/authenticity oilseeds and their by-products.
Olga, Govedarica. „Određivanje optimalnih uslova izvođenja procesa epoksidovanja biljnih ulja persirćetnom kiselinom“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2017. http://www.cris.uns.ac.rs/record.jsf?recordId=104159&source=NDLTD&language=en.
Der volle Inhalt der QuelleVegetable oils can be transformed into added valueproducts by various chemical modifications, such asepoxidation. The epoxidized vegetable oils have awide range of applications in the chemical andpolymer industry. The quality, and consequently theapplication, of epoxidized vegetable oil is influencedby the epoxy group content. Since the epoxy groupsare formed by the oxidation of double bonds intriglycerides, the main constituent of vegetable oils,highly unsaturated vegetable oils, such as linseedoil, are desirable raw materials.The manufacturing of epoxidized vegetable oilsrequires the optimization of the process conditionsin order to achieve complete conversion of doublebonds and high selectivity of the process in respectto the epoxy groups. Therefore, the aim of thisdoctoral thesis is to determine the optimal processconditions for the epoxidation of linseed oil withperacetic acid, formed in situ from acetic acid and30% hydrogen peroxide in the presence of an ionexchange resin as the catalyst. The optimal processconditions were determined by response surfacemethodology, as well as by using developed pseudohomogeneouskinetic models that describe theinvestigated reaction system. For both optimizationmethods, the relative epoxy yield was selected as anobjective function to be maximized.The effects of process conditions, such astemperature, molar ratio of reactants, catalystamount and steering speed, on the kinetics of theepoxidation were studied in order to defineconstraints for the optimization. To avoid longreaction times, which are not of interest inmanufacturing, an adequate temperature range wasselected. Under the optimized process conditions for theepoxidation of linseed oil, which were determinedby response surface methodology, good agreementbetween the calculated and experimentallydetermined relative epoxy yields was achievedwithin 3.28%.Three models describing the three-phase multireactionsystem of vegetable oil epoxidation withperacetic acid were developed and further used forthe optimization. The models are pseudohomogeneouswith respect to the catalyst. Besidesthe kinetics of the main reactions of peracetic acidand epoxy group formation, the models take intoaccount the side reaction of the epoxy group openingwith acetic acid. The partitioning of the acetic acidand peracetic acid between the oil and aqueousphases is considered. In two proposed models, theeffect of fatty acid composition on the kinetics of theprocess is also described by considering the numberof double bonds in the fatty acid chains. Thedeveloped empirical correlation for the partitioncoefficient for acetic acid between the liquid phasesshows good agreement between the calculated andexperimental data. The kinetic parameters of theproposed pseudo-homogeneous models weredetermined by fitting the experimentally determinedchanges of the double bond and epoxy groupamounts with reaction time of the epoxidation.Statistical values of the models` parametersdetermination confirmed the hypothesis that thepseudo-homogeneous model proposed in theliterature can be improved by considering thepartitioning phenomena and the effect of the oil fattyacid composition on the kinetics of the vegetableoils epoxidation with peracetic acid.Under the optimized process conditions for theepoxidation of linseed oil with peracetic acid formedin situ in the presence of the ion exchange resin,which were determined by using proposed pseudohomogeneousmodels, the experimentallydetermined relative epoxy yield was 5.51% lowerthan the calculated.Better agreement between the calculated andexperimentally determined values for the relativeepoxy yield, achieved under the optimal processconditions, is obtained when the response surfacemethodology (RSM) was applied as opposed towhen the kinetic models were used for thedetermination of the optimal process conditions.This is in accordance with better fitting of therelative epoxy yield by RSM regression equationthan by kinetics models. Standard deviation of therelative epoxy yield for RSM regression equation is 8.9 times lower than the standard deviation for themost successful kinetic model used for prediction ofthe optimal process conditions for the epoxidation ofthe linseed oil by peracetic acid.
Dragiša, Đorđić. „Revitalizacija i sagorevanje otpadnih transformatorskih i motornih ulja u funkciji zaštite životne sredine“. Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2020. https://www.cris.uns.ac.rs/record.jsf?recordId=112424&source=NDLTD&language=en.
Der volle Inhalt der QuelleThe doctoral thesis cover the testing of revitalization, combustion parameters and emissions of waste transformer and motor oils, as well as their diesel mixtures. The experimental results obtained indicate that after the revitalization treatment, the insulating properties of the transformer oil are significantly improved, which is very important for the safe operation of transformer, environmental protection and work environment. In addition, the results of an experimental test of the combustion process indicate that waste transformer and motor oils and their mixtures with diesel can be used as fuel in low power heat generators and in various branches of the process industry, and can reduce environmental issues.
Zoran, Zeković. „Ekstrakcija timijana (Thymus vulgaris L.) superkritičnim ugljendioksidom“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 1999. https://www.cris.uns.ac.rs/record.jsf?recordId=71448&source=NDLTD&language=en.
Der volle Inhalt der QuelleAbstract was processed by technology for Optical character recognition (OCR).The extraction of thyme (Thymus vulgaris L.) by supercritical carbon dioxide as an extragent was investigated. The developed HPLC (High Pressure Liquid Chromatography) method for determination of pharmacologically active phenolic compounds, thymol and carvacrol, showed a high reproducibility (Kw for thymol 1.29%). Qualitative and quantitative analyses of thyme products, essential oil and extracts, were carried out by gas chromatography - mass spectrometry (GC-MS). The content of essential oil determined by an official procedure given by Yugoslav pharmacopoeia was 1.75% (V/w). The predominant compound of the essential oil is thymol (50.06%; w/w), while carvacrol is present, practically, in traces (1.15%; w/w). The content of n-tetradecane in the thyme essential oil (16.11%; w/w) is higher than that of other paraffins. In the total thyme extract obtained by methylene chloride using extraction with periodical exchange of the extract (Soxhlet extraction) in a yield of 4.95%(w/w), the predominant compound was n-tetradecane (47.18%), while the content of thymol was 16.11%.The extraction kinetic of thymol can be successfully expressed by analogy to first order reaction kinetic, and a highest value of extraction rate constant (k) of 0.2209 h-1 for the selected flow rate of supercritical carbon dioxide of 97.725 dm3/h.A quantitative extraction of thyme essential oil by supercritical carbon dioxide (100 bar; 40°C; 2.5hours) was obtained using thyme of the grinding degree d2 (mean particle diameter 0.35 mm). The composition of this extract is very similar to that of the essential oil obtained by steam distillation. A higher yield of extraction, primarily of paraffins, was obtained by prolonging the extraction time over 2.5 hours. The use of carbon dioxide of low solubility power (80 bar; 400C; d =0.1918 g/cm3) did not yield a quantitative extraction of thyme essential oil.Ву increasing extraction pressure from 100 to 400 bar, i.e. solubility power, the extract composition was more and more similar to the composition of total extract obtained by methylene chloride.То model extraction of the system thyme - supercritical carbon dioxide use was made of the Reverchon - Sesti Osseo equation: Y = 100 [1-exp(-t/ti)]where: Y - normalized extraction yield (%); t - extraction time (s) and ti - internal diffusion time (s)i.e. of its modified form: Y = 100 [1 - ехр (at + b)]The calculated values of standard error of regression (SY,X) show that the modified equation is generally a better fit for the normalized yields of total extract and thymol compared to the original equation.Equations: log S = a mrel + band log S = a dC02 + bwhere: S - solubility of total extract (g/dm3), i.e. of thymol (mg/dm3) in carbon dioxide; mrel - relative mass of carbon dioxide (g CO2/g thyme) and dCO2 carbon dioxide density (g/cm3)could be successfully used for modelling of the investigated extraction system.The composition of thyme extract obtained by liquid carbon dioxide (65 bar; 23°C ) is very similar to that obtained by supercritical extragent at a pressure of 100 bar.То obtain a thyme extract whose qualitative and quantitative characteristics are most similar to those of the essential oil obtained using official procedure by steam distillation, it is necessary to use a carbon dioxide density of 0.6302 g/cm3 (100 bar; 400C), grinding degree of thyme d2, extraction time of 2.5 hours and extragent flow rate of 97.725 dm3/h.
Branislava, Nikolovski. „Kinetika i modelovanje ekstrakcije ulja iz bobica kleke (Juniperus communis L.) i semenki tikve (Cucurbita pepo L.) natkritičnim ugljendioksidom“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2009. https://www.cris.uns.ac.rs/record.jsf?recordId=71281&source=NDLTD&language=en.
Der volle Inhalt der QuelleThis study provides results of supercritical carbon dioxide (SCCO2) extraction of juniper berries (Juniperus communis L.) and pumpkin seeds (Cucurbita pepo L. convar. citrullina) in a laboratorysupercritical fluid extraction apparatus. The influenceof pressure, temperature, particle size and carbon dioxide flow on the extraction kinetics of pumpkin seed oil and juniper berry essential oil was studied. Ground pumpkin seeds were also extracted with supercritical carbon dioxide in NOVA-SWISS, High Pressure Extraction Plant, and with hexane and petroleum ether in a laboratory Soxhlet extractor. This work was also aimed to investigate the evolution of the composition of juniper fruit supercritical CO2 extracts with time, at different extraction pressures and to emphasize the most favorable condition for the extraction of different terpene hydrocarbon groups, reporting the qualitative differences among extracts collected during successive extraction time periods. Juniper berry extracts were analyzed by capillary gas chromatography, using flame ionization (GC-FID) and mass spectrometric detection (GC-MS). More than 200 constituents were detected in the extracts and the contents of 50 compounds were reported in the work. Dependence of the percentage yields of monoterpene, sesquiterpene, oxygenated monoterpene and oxygenated sesquiterpene hydrocarbon groups on extraction time was investigated and conditions that favored the yielding of each terpene groups were emphasized. GC-MS analysis of FAME, prepared by transesterification of pumpkin seed oil with KOH in methanol, was performed. Fatty acid compositions of supercritical CO2 pumpkin seed extract fractions collected in successive time intervals over the course of the extraction were determined. The same fractions were analyzed by high pressure liquid chromatography (HPLC), using diode-array detector (DAD) in order to determine a- and g-tocopherol contents. Sterol and squalene contents were determined by GC-MS analysis, as well. Conditions that favored the yielding of tocopherols, squalene and sterols were emphasized. A general mass transfer model and its simlifications were analysed. Extraction curves were evaluated by “hot sphere” mathematical models SSM-1 (Single Sphere Model 1 – in which the external mass transfer coefficient also influences the extraction profile and film mass transfer coefficients were estimated by the correlations), SSM-1 (2 par) (film mass transfer coefficient is used as the second adjustable parameter), SSM-2 (only effective diffusivity influence is considered), Characteristic time model and by the extended Lack’s plug-flow model given by Sovová. A combined model of Hong et al. was also fitted to the experimental data for pumpkin seed oil SCCO2 extractions. Relative merits of the models are demonstrated. Good agreement between the extended Lack’s plug-flow model and the experimental measurements was obtained.
Milovan, Janković. „Matematički model reakcionog sistema za in situ epoksidovanje sojinog ulja persirćetnom kiselinom“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2013. https://www.cris.uns.ac.rs/record.jsf?recordId=83242&source=NDLTD&language=en.
Der volle Inhalt der QuelleThe objective of this doctoral thesis was development ofmathematical model for complex three-phase reactionsystem for soybean oil epoxidation with peracetic acidformed in situ from acetic acid and hydrogen peroxide in apresence of an ion exchange resin as catalyst. The localconcentrations of components in water and oil phases wereintroduced into the model. In addition to reactions of theperacetic acid and epoxy compound formation, modelconsiders the side reaction of epoxy ring cleavage withacetic acid. Approximate modeling of peracetic acidformation was based on Langmuir-Hinshelwood-Hougen-Watson and Rideal-Eley postulates. Established threephasemodel is a system of ordinary first order differentialequations which describes change of components andfunctional groups amounts with reaction time. Besideskinetic parameters, model comprises the thermodynamicones as well as parameters of mass transfer between the oiland water phase. All model parameters are dependent ontemperature and some additionally on composition andintensity of stirring.A semitheoretical temperature dependency of chemicalequilibrium constant for peracetic acid formation wasestablished. The order of magnitude and temperature trendof the calculated chemical equilibrium constant are inagreement with the most data given in a literature.For calculation of partition coefficient for acetic acidbetween oil and water phase, temperature and compositiondependency of liquid-liquid equilibrium constant for aceticacid is necessary. It was found that UNIFAC model ofgroup contribution was non-applicable for the predictionof the equilibrium constant. The experimental data for theequilibrium constant were, however, successfully fitted byUNIQUAC model.Temperature dependencies of the reaction rate constantsand sorption constants of reactants and products inperacetic acid formation reaction are expressed byreparameterized Arrhenius equation. The parameters ofsuch equation were determined simultaneously with masstransfer parameters and ratio of peracetic acid and aceticacid partition coefficients between oil and water phase byfitting the experimental data i.e. by minimization of leastsum of squares of deviation between the calculated andexperimentally determined iodine value and epoxy oxygencontent . Marquardt method was successfully used to fitthe experimental data. A fourth-ordered Runge-Kuttamethod was applied for integrating the system ofdifferential equations of the model.
Predrag, Kukić. „Uticaj ekstrudiranja na promene odabranih fizičko-hemijskih svojstava soje“. Phd thesis, Univerzitet u Novom Sadu, Poljoprivredni fakultet u Novom Sadu, 2018. https://www.cris.uns.ac.rs/record.jsf?recordId=104284&source=NDLTD&language=en.
Der volle Inhalt der QuelleAB The aim of this research is to determine the changes in chemical composition of the products at the outlet of the extruder and press (soya meal and oil), i.e. their quality in terms of their further use in animal feed production, food industry or the further use of soybean oil in bio-diesel production, with the functional correlation between the variable characteristics of feedstock and operating parameters of the extruder. Extrusion of soybeans was carried out on the extruder, type E-751, manufactured by "SREM PRODUKT" DOO from Lacarak, and pressing of oil on the press, type PM-5S, manufactured by "BRONTO" from Ukraine. Studies that were conducted in this PhD Thesis were done as a contribution to the expansion of knowledge related to the production process of soya cake and soya oil, and to provide practical guidelines for the optimal control and modeling of the extrusion process and squeezing soybeans, as well as for the designing of the extruder. Some experimental and laboratory tests were conducted in order to obtain and to analyze data that could determine changes in chemical composition of the products at the outlet of the extruder and press (soya cake and oil), i.e. their quality in terms of their further use in animal feed production, food industry or the further use of soybean oil in bio-diesel production, all with the functional correlation between variable characteristics of feedstock and operating parameters of the extruder. Experimental researches are intended for practical application, by which the production process of soya cake and soybean oil could be enhanced and optimized. The results obtained in these researches can be useful to everyone involved in the production of soya cake and soya oil. Experimental studies were carried out on the extruder, type E-751 and the press, type PM5S, but the results are also applicable to other extruders and presses from other manufacturers, that use soybean as a raw material and produce soybean cake and soybean oil. The conducted researches, processed and discussed results have led to the functional correlations between different extrusion parameters and variable characteristics of the incoming raw___________________Doktorska disertacija, autor:Kukić Predrag____________________________________________________________________________________IX od 34materials on the one hand, and the characteristics of the extrudate and soybean oil on the other hand, and further on to the certain conclusions. Based on the experimental researches, the impact of changes in selected physical and chemical properties of soybeans was evaluated in the extrusion of soybeans. The PhD Thesis started with the analysis of raw material i.e. soybean and its composition: protein, oil, free fatty acids (FFA) and moisture, and then, the content of free fatty acids, phosphorus and moisture in soybean oil after pressing the extrudate were monitored, as well as protein, moisture, oil, urease activity and PDI (Protein Dispersibility Index) in soya cake by varying the operating mode of the extruder, i.e. feeding of raw material, monitored via load of the main drive motor of the extruder expressed through amperage [A], the die openings surface and moisture of soybeans. The conducted researches have led to the functional correlations between the preset operating modes of the extruder, incoming raw material and selected physical and chemical properties of soybeans in the extrusion process. Thus, with increasing the die openings surface and feeding mass, the production of soya cake is being increased as well. Production of soya cake is also increased with the increase of moisture in the incoming raw material. Moisture content in soya cake is being increased with the increase of moisture content in a feedstock and interactions of feeding mass and the die openings surface. Based on the conducted researches, it can be concluded that the oil content in soybean cake is being increased with the increase of the extruder die openings surface for each of the three moisture content in soybean as a feedstock, while the oil content in soybean cake is being decreased with increased dosage of feedstock for each of the three extruder dies. By increasing the surface area of the extruder die openings, there is a decrease of the protein content in soya expeller cake, while vice versa, with an increase in the dosing of input raw material, i.e. with increasing dosage of raw material to the extruder, the protein content in soya expeller cake is increased. The positive effect of urease activity (ΔpH) in soya cake is for larger values of the surface of extruder die___________________Doktorska disertacija, autor:Kukić Predrag____________________________________________________________________________________X od 34openings as well as for the interaction of variables W (moisture in soybean) and D (soybean mass dosage determined via the load of the main electric motor). PDI in soybean cake increases with the increase in moisture content of raw material, the surface of the extruder die openings and the dosing of soybeans as a feedstock. Considering the data obtained for soybean oil, manufactured by squeezing the extruded soy product with the predicted moisture content in the feedstock, it has been concluded that the oil production decreases with increasing the surface of the extruder die openings, while by increasing the dosage of incoming raw material, the production of soybean oil is increased. Moisture content in soybean oil is reduced with the increase of the surface of the extruder die openings, as well as with an increase in dosage of feedstock. Based on the evaluated model, the largest values of FFA content were achieved with the smallest considered values for the moisture content in the incoming feedstock, wherein the content of FFA increases with increasing the feeding mass. The phosphorus content in the oil decreases with increasing the feeding of raw material into extruder. Higher extrusion temperatures [oC] are achieved at the lower values of moisture and surface of extruder die openings. With increasing the feeding mass and fixed values of moisture content and die openings surface, the expected value of the extrusion temperature decreases. With increasing the dosage of raw materials into the extruder, the largest expected value for the energy, spent per kilogram of production (soybean cake + soybean oil), decreases. By increasing the dosage of raw materials in the extruder, the largest expected value for the energy, spent per kilogram of soya cake production, is reduced. With increasing the dosage of raw materials in the extruder, the lowest expected value of energy, spent per kilogram of soybean oil production, increases
Svetlana, Milošević. „Ekstrakcija ginka (Ginkgo biloba L.) ugljenik (IV)-oksidom pod pritiskom“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2011. https://www.cris.uns.ac.rs/record.jsf?recordId=76803&source=NDLTD&language=en.
Der volle Inhalt der QuelleWithin this thesis preparative isolation of essential oil from leaves of ginkgo (Ginkgo biloba L.) by steam distillation was carried out, in order to determine some physico-chemical parameters. The essential oil content in the leaves of ginkgo wass determined by an officinal procedure and its value is 0.0083%. Ginkgo leaves were extracted with conventional solvents, i.e. alcohol-water mixture, where the alcohol concentration was 40% (w/w). The forementioned solvent was used to carry out a multistage counter-current extraction (five stages) by which the liquid extract (Extracta fluida) with a relatively high content of extracts (17.06%) was obtained. The liquid extract was directly used to obtain a dry extract of ginkgo leaves (Extracta sicca) by spay drying. The qualitative and quantitative characterisation was based on the proceedings of liquid thin layer chromatography (HPTLC), the content of total flavonoids expressed as rutin, and as catechin, and the total phenol content expressed as chlorogenic acid was determined. The main part of the doctoral thesis is the extraction system of ginkgo leaves-carbon (IV) oxide under pressure, in which the effect of the drug particle size on the extraction yield was studied, and as a measure of the kinetic behavior of extraction the coefficient of fast and slow extraction was used. The obtained results showed a significant effect of the drug particle size on the speed of extraction, particularly, the extraction with supercritical carbon (IV) oxide. For the purpose of selecting the optimal flow of the solvent several flowrates were investigated 0.095, 0.194 and 0.277 kg/h. Based on the yield of extraction the solvent flowrate of 0.194 kg/h was assumed as optimal. The extraction yield was investigated using two extraction procedures: extraction with liquid carbon (IV) oxide (temperature below the critical temperature Tc = 31.1 0C and pressure slightly below or above the critical pressure pc = 73.8 bar), and extraction with supercritical carbon (IV) oxide (pressure and temperature above the critical values of pressure and temperature). In the supercritical area the change in pressure significantly the influences the properties of the solvent, increases the ability of dissolving, dielectric constant, etc. The effect of temperature on extraction yield was examined (isothermal process), where the obtained results can not be explained simply by analyzing only the effect of solvent density on the power of dissolution, but to explain these results the effect of vapor pressure of the extracted components must be included, so that the solubility of the component may increase, decrease or remain the same with increasing temperature at constant pressure, depending on which influence is dominant. In isothermal processes the extraction yield increases with increasing pressure of extraction, which is consistent with theoretical principles. On the other hand, extracts obtained at high pressures have a lower content of essential oils which can be explained by the fact that higher pressures have a greater power of dissolution of the main components as well as components such as resins, waxes and fatty oils. The qualitative and quantitative analysis of the selected extracts obtained with liquid (130 bar, 20 0C, 3 h) and supercritical (100 bar, 40 0C, 4 h) carbon (IV) oxide, and essential oils isolated from these extracts showed that the studied samples contain n-alkanes, branched alkanes and compounds with oxygen, including phenols with saturated and unsaturated alkyl residues. A comparative analysis of the essential oil obtained by distillation of ginkgo leaves by steam and essential oil obtained from selected extracts was carried out. An interesting fact concerning the essential oil content in the drug determined by direct distillation of drugs by steam and separating the essential oils from extracts also produced by steam distillation. In the other case, by calculation, the obtained essential oil content in the drug is several times higher (4-10 times) of content, determined by an fficinal procedure, in the drug. This phenomenon is explained by introducing the notion of "linked" essential oil and "free" essential oil. The extraction with carbon (IV) oxide under pressure the so called linked essential oil is released from waxes and fatty oils which is reflected in its increased amount in CO2-extracts. At the end of this dissertation the modeling of the extraction system leaves of Ginkgo biloba - carbon (IV) oxide under pressure was carried out using the model equation of Naik and associates, the modified model equation of Reverchon and Sesti Osseo and also like a frequently used model proposed Sovová. The mentioned models can be relatively used to describe the extraction system leaves of Ginkgo biloba - carbon (IV) oxide under pressure. In order to find the most favorable conditions of extraction, the response surface methodology varying extraction parameters was used (pressure, temperature and extraction time). Based on the experimental results a second order polynom for the calculation of the optimum yield of extraction was obtained and the extraction conditions and the mutual influence of some parameters were determined.
Ranko, Romanić. „HEMOMETRIJSKI PRISTUP OPTIMIZACIJI TEHNOLOŠKIH PARAMETARA PROIZVODNJE HLADNO PRESOVANOG ULJA SEMENA VISOKOOLEINSKOG SUNCOKRETA“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2015. http://www.cris.uns.ac.rs/record.jsf?recordId=95781&source=NDLTD&language=en.
Der volle Inhalt der QuelleIn this dissertation the optimal conditions for the dehulling process of high-oleic sunflower seeds, as raw material for oil production, were tested and determined. The conducted studies provided data for the optimal values of moisture content in the seed and the air pressure in the seed dehulling machine, what presented the base for determination of the dehulling model. Also, conducted studies examine the effect of variable technological parameters, such as content of hull (ranging from 0 to 20%) and the impurities content (ranging from 0 to 10%) on the composition and quality of oil and cake, oil yield, oxidative stability, sensory quality and colour of cold pressed high-oleic sunflower oil.The obtained results were analyzed by modern classification (cluster analysis and principal component analysis) and regression chemometrics methods, and chemometric models whose implementation could contribute to the production of cold pressed oil of high quality and high oxidative stability were set. It was found that the defined mathematical models are statistically valid and that they could be used to optimize the technological parameters of production of cold pressed high-oleic sunflower oil. The validity of the set models, that is the quality of obtained correlations, were estimated based on the parameters of cross-validation.The maximum effectiveness of high-oleic sunflower seeds dehulling can be achieved under optimal conditions, i.e. when the moisture content in seed is 6,0% and when the air pressure in seed dehulling machine is 800 kPa. Regarding composition and quality of the oil and cake, oil yield, oxidative stability, sensory quality and color, cold pressed high-oleic sunflower oil could be produced from seed containing 10-20% hull and 0-5% impurities.
Branimir, Pavlić. „Valorizacija sporednog proizvoda žalfije (Salvia officinalis L.) u cilju dobijanja bioaktivnih jedinjenja savremenim tehnikama ekstrakcije“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2017. http://www.cris.uns.ac.rs/record.jsf?recordId=104416&source=NDLTD&language=en.
Der volle Inhalt der QuelleThe main aim of this dissertation was valorization of sage (Salvia officinalis L.) by-product from filter-tea factory for recovery of high-value extracts with desirable properties for application in food, cosmetics and pharmaceutical products.Conventional (maceration) and novel (ultrasound-assisted, microwave-assisted and subcritical water extraction) extraction techniques were applied for polyphenols recovery. Ethanol concentration was optimized in maceration process, while experimental design and response surface methodology were applied for optimization of novel extraction techniques. Polyphenols yield (total phenols and total flavonoids) and antioxidant activity, determined by various in vitro assays, were investigated responses. Influence of main process parameters was determined for each technique: ultrasound-assisted extraction (temperature, extraction time and ultrasonic power), microwave-assisted extraction (ethanol concentration, extraction time and sample-solvent ratio) and subcritical water extraction (temperature, extraction time and HCl concentration in solvent). Liquid extracts obtained by novel extraction technique exhibited higher antioxidant activity determined by scavenging of DPPH and O2∙- radicals and reduction of Fe3+ and also provided higher polyphenols yield comparing to extracts obtained by maceration. Soxhlet extraction, hydrodistillation and supercritical fluid extraction were applied for terpenoids recovery. Supercritical fluid extraction process was optimized by response surface methodology and optimal conditions were pressure of 290 bar, temperature of 55˚C and CO2 flow rate of 0.4 kg/h, while predicted and experimentally obtained values of total extraction yield at these conditions were 8.90 i 8.84%, respectively. According to chemical analysis, the most abundant compounds in lipid extracts and essential oil were oxygenated monoterpenes (α-thujone and camphor), oxygenated sesquiterpenes (viridiflorol) and diterpene polyphenols (epirosmanol).Sage liquid extracts obtained by conventional and novel extraction techniques were spray dried in order to obtain dry extract form. Physico-chemical properties (chemical profile, moisture content, hygroscopicity, rehydratation time, WAI and WSI) and biological activity (antimicrobial and antioxidant activity) were determined in dry extracts and their potential application in food and pharmaceutical formulations was discussed.
Mohamed, Elgndi Ahmed. „Farmakološko delovanje ekstrakata odabranih aromatičnih/lekovitih biljaka“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2018. https://www.cris.uns.ac.rs/record.jsf?recordId=106922&source=NDLTD&language=en.
Der volle Inhalt der QuelleThe main aim of this dissertation was recovery and chemical characterization of extracts and essential oils of winter savory (Satureja montana L.), basil (Ocimum basilicum L.) and coriander (Coriandrum sativum L.), as well as their mixture, and determination biological activity of extracts in in vitro conditions by capacity towards neutralization of free radicals and antiproliferative activity.Plant materials (winter savory, basil and coriander) and their mixture (CBS) were characterized in terms of moisture content, mean particle size and essential oil content. In order to obtain essential oil and extracts from investigated plants, hydrodistillation (conventional procedure) and supercritical fluid extraction (novel technique) were applied. GC-MS analysis was used for determination of qualitative content and relative abundance of monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpenes and other volatile compounds. Furthermore, GC-FID analysis was used for quantitative determination of content and yield of terpene compounds (α-pinene, β-pinene, d-limonene, γ-terpinene, eucalyptol, linalool, camphor, α-terpineol, geraniol, methyl-chavicol, carvacrol i eugenol) and samples obtained by traditional and novel techniques were compared. Biological potential of essential oil and lipophilic extracts was determined by antioxidant and antiproliferative activity. In vitro antioxidant activity of supercritical extracts and essential oils was determined by DPPH assay, while antiproliferative activity was determined in in vitro conditions on three cancer cell lines (HeLa, MDA-MB-453, K562) and on normal human fibroblasts (MRC-5).Chemometric techniques such as principal component analysis (PCA) i hierarchical cluster analysis (HCA) were applied for better understanding of similarities between essential oils and lipid extracts.
Jelena, Bajac. „Dobijanje emulzionih nosača aktivnih materija primenom homogenizera i membranskim emulgovanjem u ćeliji sa mešanjem“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2018. https://www.cris.uns.ac.rs/record.jsf?recordId=107583&source=NDLTD&language=en.
Der volle Inhalt der QuelleThe aim of this doctoral thesis was to prepare multiple W/O/W emulsions with encapsulated active substances in both phases, by a two-step process, where the stirred cell membrane emulsification (ME) process, with a sintered glass filter disk as a membrane, was used as the second step, instead of conventional process (homogenization). The ME process was employed in order to improve the characteristics of the formed emulsions, in terms of better control of the size and droplet size distribution, that can change the encapsulation degree of active ingredients in the internal aqueous phase.The complete optimization of W/O emulsion composition, which includes determination of optimal contents of a hydrophobic emulsifier (PGPR), a lipophobic substance (NaCl) and pumpkin seed oil as an active component of the oil phase, resulted in the formation of stable nanoemulsions with improved nutritional properties. This nutritionally enhanced emulsion was used to encapsulate primary active ingredients (aqueous and ethanol garlic extract), in order to protect instable bioactive compounds of the extracts and mask the unpleasant smell and taste. After defining the composition of all phases of multiple emulsions, which includes determination of a suitable hydrophilic emulsifier and its optimal content, as well as examining the effect of addition of an osmotic regulator (glucose) in the external aqueous phase on the emulsion stability and lipophobe diffusion, multiple emulsions with encapsulated active components were formed by membrane emulsification in the stirred cell. The complete characterization of the sintered glass as an economically favourable membrane material, gave the possibility of its application in the process. Investigation of the influence of process parameters (transmembrane pressure and impeller rotation speed) and multiobjective optimization of ME, led to the formation of the multiple emulsions with a narrow droplet size distribution, which had improved retention of encapsulated material in the internal water phase over time, relative to the emulsions prepared by the homogenization process.
Marina, Kalić. „Fizičko-hemijska i reološka karakterizacija mikrokapsula ribljeg ulja inkorporiranih u čokoladni matriks“. Phd thesis, Univerzitet u Novom Sadu, Medicinski fakultet u Novom Sadu, 2020. https://www.cris.uns.ac.rs/record.jsf?recordId=114094&source=NDLTD&language=en.
Der volle Inhalt der QuelleOmega-3 fatty acids are essential for human health and have significant physiological roles. Dietary products based on omega-3 fatty acids are a significant source of omega-3 fatty acids. Fish oil is a good source of polyunsaturated fatty acids (PUFA). The daily intake of omega-3 polyunsaturated fatty acids is below the recommended level in most parts of the world, mainly due to the lack of fish in the diet. This is why fish oil is now found as various dietary products which are widely present in the world’s market. The problem with fish oil intake as a dietary supplement is its intense and unpleasant taste and odor, which can lead to inadequate supplementation. Spray drying is a technique that allows instantaneous drying of solutions, suspensions or emulsions. It is a widely used method in the pharmaceutical industry and is used, among other things, to mask the unpleasant taste of medicines. It is possible to use proteins as a coating of spray-dried microcapsules, but it is necessary to test and know their physicochemical properties and functionality. Incorporating fish oil microcapsules into chocolate would make functional or enriched foods, which is consider as a final formulation in this work. Enriching the high cocoa content chocolate with fish oil microcapsules would create a multi-functional product. The choice of chocolate as a base is conditioned by the fact that it is a widely consumed product. The aim of this study was to investigate the effect of spray drying method on the stability of fish oil pre-formulation, to determine the characteristics of microcapsules obtained by spray drying (yield and efficiency of microencapsulation, oxidative stability of oil, morphological properties and size of microcapsules), to determine the effect of particle size crystallization in the oil phase of the suspension used for confectionery products and to determine the physicochemical characteristics (texture, color, rheological properties) of chocolate containing fish oil microcapsules in comparison with chocolate without the addition of microcapsules. Methods included characterization of proteins obtained from soybeans, peas, potatoes, rice and whey, their solutions, as well as fish oil emulsions in aqueous solutions of these proteins, determination of the yield and efficiency of microencapsulation, and characterization of the microcapsules obtained. In the examination of the effect of particle size on crystallization in the oil phase of the suspension used for the manufacture of confectionery and physicochemical properties of chocolate containing fish oil microcapsules, methods were used to determine the texture, rheological characteristics, solid fat content and color of the formulations obtained. The results show that proteins act as good emulsifiers and that spray drying is an effective way to obtain fish oil microcapsules with proteins as microcapsule shells. The crystallization of the oil phase in the suspension representing the chocolate model depends on the size of the solid particles. In the case of production of chocolate with incorporated fish oil microcapsules using soybean, whey and potato proteins as coating material, the addition of these microcapsules does not affect the chocolate characteristics to a degree sufficient to impair the manufacturing process. All of the above points to the conclusion that the production of chocolate with incorporated fish oil microcapsules would be technologically possible.
Boris, Župan. „UTICAJ DODATKA LANENOG ULJA U HRANI NA PROMENU SADRŽAJA MASNIH KISELINA U MIŠIĆNOM TKIVU ŠARANA“. Phd thesis, Univerzitet u Novom Sadu, Poljoprivredni fakultet u Novom Sadu, 2016. https://www.cris.uns.ac.rs/record.jsf?recordId=97698&source=NDLTD&language=en.
Der volle Inhalt der QuelleThe aim of this study was to determine to what extent adding flaxseed oil to pellet diet andfattening carp so enriched food affects the amount of fat and the composition of fatty acids infish meat. Feed mixtures in all the studied groups were the same composition, except for theaddition of linseed oil to be changed (2.0; 3.0; 4.0; 5.0% and 6%) and fat (Magnapac), whichwas reduced by the same percentage value addition linseed oil. During substantial period ofresearch physico-chemical parameters of water in all experimental ponds ranged in valuessuitable for the cultivation of warm-water fish. Share C18:1 cis-9 was statistically significantlylowest in the control group and amounted 35.43%. By increasing the value of flaxseed oilincreases the proportion of C18:1 cis-9. Statistical highest value of C20:0 in the samples fedwith the addition of 5% linseed oil. The lowest value of C20:3 ω-3 in the control group is0.22% and significantly highest in the group that feeds supplemented with 5% linseed oil. Dueto the addition of linseed oil in the food, there is no significant difference in total saturated,monounsaturated, polyunsaturated omega-6 fatty acids. The largest proportion of ω-3 fattyacids found in samples of carp which was in food supplemented with 5% linseed oil (5.41%).The experimental results of the second experiment show the usefulleness of using of linseed oilin fish food regearging the meat quality. The ratio ω-3/ω-6 fatty acid increased significantly inthe group that is added to food in a higher proportion of linseed oil (0.21 in the control groupto 0.30% in the group with addition of 5% linseed oil). The value of cholesterol was notsignificantly changed by adding linseed oil to the diet of carp.Accepted on Senate on:AS
Snežana, Filip. „Ekstrakcija bosiljka (Ocimum basilicum, Lamiaceae) ugljendioksidom u superkritičnom stanju i modelovanje ekstrakcionog sistema“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2014. http://dx.doi.org/10.2298/NS20140117FILIP.
Der volle Inhalt der QuelleIn this study, the extraction of basil (O. basilicum L.) ussing the hydrodistillation process, Soxhlet extraction and supercritical extraction with carbon dioxide were investigated. The content of essential oil was determined (0,565%), and the qualitative and quantitative composition of detected coumpound was made by GC/MS(FID). The identified coumpounds were classified into five groups (monoterpenes, sesquiterpenes and their oxidative derivates). The results of investigation shows that the dominant compound of basil essential oil is linalool (50,09%), and that it belongs to linalool chemotype (chemotype A).The influence of temperature (40-60°C) and pressure (100–300 bar) of supercritical carbon dioxide on extraction yields were studied. It was determined that the total yield of extract increases with the increaseing of extraction pressure, while the influence of temperature on the yield depends on the density of the solvent and vapor pressure of components in the extract.Fractional supercritical fluid extraction was performed, and obtained extracts were compared regarding of yield, and the qualitative and quantitative composition of the extract. Chemical analyses of CO2 extract by GC/MS and GC/FID showed that extract contains, besides essential oil componentes, other lipophilic compounds (waxes, fatty oils, fatty acids, phytosterols, etc.). The few compounds were dominant in all analyzed basil extracts: linalool, and to a lesser extent eugenol, δ-cadinene, α-bergamotene, germacrene D, γ-cadinene, β-selinene and spathulenol. Based on the experimental results of the extraction kinetics, a modeling of basil – supercritical CO2 extraction system was performed, using three models (Kandiah and Spiro, Brunner, and Esquivel et al.). Based on the average values of the relative deviations of modeled and experimental values of extraction yield, it was found that the model Kandiah and Spiro shows acceptable agreement, while other models show lower agreement of the experimentally determined and model calculated extraction yield.In finale phase of work the antioxidant potential of essential oil and CO2 extracts were examined, using DPPH method. The highest antioxidant activity showed CO2 extract obtained at 100 bar, 60°C (IC50 = 18,93 μg/ml), which is 5 time higher then antioxidant activity of basil essential oil.
Seddiq, Mrihil Ali Esalami. „Karakterizacija kvaliteta, nutritivne vrednosti i stabilnosti devičanskih maslinovih ulja proizvedenih u različitim regionima Libije“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2018. https://www.cris.uns.ac.rs/record.jsf?recordId=107467&source=NDLTD&language=en.
Der volle Inhalt der QuelleIn this thesis, with the help of literature data, the geographical origin of olive and olive oil, its use during history, production process, sensory properties, nutritive value and composition of fatty acids and sustainability were presented. In the experimental part of the thesis, five samples of virgin olive oils-VOO produced in various olive growing regions of Libya were analyzed in detail over the two consecutive production years. The qualities of these oils are compared with the characteristics of extra virgin olive oils of the world's most famous producers, Italy. Spain and Greece. The most important fatty acids in olive oil are the seven major fatty acids - FA that are detected in the VOO samples. Oleic, palmitic and linolenic acid are dominant, while other FAs are detected in small amounts. The largest percentage of palmitic acid was found in the VOO from the Tripoli area (P ≤ 0.05). Oleic acid is dominant in all VOO samples. It has been found that the Libyan VOO from the Gharyan region has the highest concentration of oleic acid, monounsaturated fatty acids, the highest content of bioactive compounds and the best nutritional value. Bioactive compounds in olive oil are tocopherols, phenols and pigments. These compounds make olive oil very healthy. The VOO's photostability under the influence of fluorescent light for a period of 35 days was also examined. These experiments were carried out with three samples of VOO originating in Libya in comparison with oil from Italy. Samples were exposed to fluorescent light in transparent and dark brown glass containers. Changes in color characteristics were observed and the results showed that fluorescent light influences the quality of VOO more in samples in transparent packaging compared to those in dark brown packaging. In addition, the VOO color thermostability was tested using a Schaal-Oven test under the influence of a moderate temperature of 63 ± 2°C over a period of 28 days. The smallest changes in characteristics and parameters of the best quality were recorded in the Gharyan VOO sample. The sample contained several pigments and phenolic compounds compared to the sample from Italy and the loss was the smallest for the color parameters. The positive relationship between iodine and polyunsaturated fatty acids is registered with the coefficient of correlation r = + 0.927. A strong positive relationship between the content of chlorophyll and (a*) of the color value was noted, (r = + 0.859). A strong positive association between TPC and AC (1/EC50DPPH) was also observed, r was + 0.511. On the other hand, (1/EC50DPPH) showed a positive moderate correlation with TTC, (r = + 0.587).
Milena, Vujanović. „Hemijski sastav, biološke i funkcionalne karakteristike novih proizvoda od zove“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2020. https://www.cris.uns.ac.rs/record.jsf?recordId=115048&source=NDLTD&language=en.
Der volle Inhalt der QuelleThe main goal of this doctoral dissertation is to determine the chemical composition, biological and functional characteristics of new elderberry products. Elderberry products were obtained via traditional and modern technological processes. The exploitation of the natural potential of the elderberry started with the application of traditional and modern (lyophilization) drying techniques. To obtain high-value extracts of fruits and flowers, traditional (maceration) and modern (ultrasonic and microwave) extraction techniques with two solvents (50% ethanol and water) were applied. Obtaining the juice from the elderberry fruits implied the application of the traditional cold pressing method, whereas wine from the elderberry fruits was obtained in accordance with the standard procedure of wine production. The wine was exposed to different temperature treatments in different periods (60°C for 5 minutes, 60°C for 10 minutes, 70°C for 5 minutes and without heat treatment) to evaluate the biological activity of the product. The essential oil of the fruit and flower was obtained by hydrodistillation. The examination of the efficiency of the applied technological procedures of drying and extraction is based on observing the biological and functional characteristics of the obtained extracts of the said fruits and flowers. In the examined fruit and flower extracts, the dominant phenolic acids are chlorogenic and protocatechuic acid, while rutin and quercetin-3-O-hexoside are the dominant flavonoid compounds. Biological and functional characteristics were examined using various in vitro antioxidant, neuroprotective, antityrosinase, and antidiabetic tests. The application of lyophilization and microwave extraction (as modern drying and extraction techniques) increased the biopotential of the analyzed extracts. Elderberry juice, a potentially new functional product, was analyzed to define the chemical, phytochemical and nutritional composition, biological potential, and sensory characteristics. The wine was tested in order to determine the optimal conditions for the production of fruit wine. By defining the chemical and phytochemical composition and evaluating the biopotential of wine, the optimal temperature profile for obtaining one of the new functional products was determined. Based on the obtained chemical composition, it is determined that the essential oil of fruits and flowers is a potentially new natural agent for maintaining freshness and extending the shelf life of food products. Without a doubt, elderberry is a wild plant species that could be used in the future as the starting material for creating and obtaining new food products on the domestic and foreign markets.
Miloš, Bjelica. „Uticaj kvaliteta semenki grožđa na bioaktivne komponente i održivost hladno presovanog ulja“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2019. https://www.cris.uns.ac.rs/record.jsf?recordId=110946&source=NDLTD&language=en.
Der volle Inhalt der QuelleRaising new plantations and increasing the grapeprocessing capacity increases the amount of waste facedby the wine and brandy industry. The best and mostresponsible way of waste management is its furtherexploitation as by-products.In this dissertation, the possibility of using by-products from different stages of production in wineries and distilleries forobtaining grape seeds, which were used for the productionof cold pressed oil, was examined. The hypothesis isbased on the fact that grape seeds of various varietiesfrom different stages of wine production (white, rose or redwine), that is, brandy can have a completely differentchemical composition and quality that can certainly bereflected on the quality, bioactive components and stabilityof cold pressed oil.Such a product, as it is obtained by cold pressing, canbe very attractive to consumers, due to its specific sensoryand nutritional characteristics.For the needs of the dissertation, the by-products werecollected and samples were prepared from the wineriesand distilleries of the Fruška Gora vineyard. Seeds wereobtained and cold pressed oil produced from Merlot grapeseed, as representatives of red grape varieties, ItalianRiesling, as representatives of white grape varieties andSila, as new white grape varieties. Cold pressed oils wereproduced from grape seeds that did not undergo anytreatment, that is, they were obtained after pressing, duringthe production of white (Italian Riesling and Sila) and rose(Merlot) wines, then from the seeds that were fermentedduring the production of red wines (Merlot ) and seeds thathave undergone fermentation and distillation processduring the production of brandy (Merlot, Italian Riesling andSila). In addition to the mentioned seeds and oils, anaverage production sample was prepared, which is asample obtained from all collected seeds. Unrefined andrefined grape seed oil purchased on the market was usedas comparative samples. For realization of the set goal, the work on theperformance of this dissertation encompassed differentphases. In the first phase, grape seed were collected andtheir technical and technological characteristics and qualitywere examined. Then cold-pressed oils were producedfrom these seeds.In the following phases, the resulting ear, together with asample of unrefined and refined grape seed oil from themarket, were examined from the aspect of sensory andnutritional quality and differences in oil stability wereobserved. Sensory analysis was performed, pigmentatefractions, carotenoids and chlorophylls were determined,transparency was measured, and oil color parameterswere also determined instrumentally. The nutritive oilquality was examined based on the content andcomposition of bioactive components, primarily tocopherolsand tocotrienols, phenols and sterols. Since thesecompounds exhibit significant antioxidant activities, theantiradical activity of the samples was also tested. Thestability of grape seed oils was examined based on theinitial quality and the oxidative state, as well as the resultsof accelerated tests, such as Rancimat test, Schaal-ovenand fluorescence test.On the basis of the obtained results, it can be concludedthat all the obtained seed samples had good storagemoisture, which, given the small content of oil in the seeds,can ensure the storage of seeds for a longer period. Thecontent of oil in the seed, in addition to the influence of thegrape variety, depends on the influence of the process towhich the seeds are subjected to pressing (fermentation,distillation). Sensory analysis grape seed oils showed significantdifferences in characteristics that are due not only to themethod of obtaining oil (cold pressed or refined), grapevarieties, but also the method of obtaining, the origin andquality of grape seed. The conditions for grape seedsexposed during fermentation and especially distillationaffect the formation of a specific cold pressed oil. Althoughan extremely wide range of different flavors, odors andflavors in oil appear, and there are significant differences inthe aroma of the oil, depending on the grape variety, it ispossible to recognize whether the cold-pressed oil isderived from the grape seed without fermentation, afterfermentation or after distillation. Also, from the aspect of oilcolor it can be said that refined grape seed oil has a lightyellow color with a greenish shade, while cold pressedgrape seed oils have more intense colors range fromyellowish-greenish, over greenish yellow and light greenishto dark green. A higher proportion of green color has coldpressed grape seed oils obtained after distillation.The thesis has shown that the content of pigments(carotenoids and chlorophyll) depends to a great extent onthe origin of the seed. The fermentation processcontributes to increasing the content of pigments, while thedistillation process has a negative effect due to hightemperatures.Transparency of cold pressed grape seed oils producedfor the dissertation ranged from 32.8% to 53.8%.The content of unsaturated fatty acids in all samples ofgrape seed oil is greater than 90%, with the dominant fattyacid being linoleic, omega-6, fatty acid. The content of tocotrienols is higher than the content oftocopherols in grape seed oils, and the dominanttocopherol is alpha-tocopherol. Its content is higher in oilsamples obtained from the seed after fermentation anddistillation.The content of phenol compounds, depending on thevariety, is somewhat higher in cold pressed oils obtainedfrom red grape varieties, but there is also a significantincrease in accumulation of phenol in cold pressed oilsobtained from the grape seed after the fermentation anddistillation process. The largest individual oil content ofgrape seeds has ursolic acid, and besides it, significantcontent, although much smaller, shows rezveratrol,kemferol and vanillinic acid.The most prevalent sterols of grape seed oils are β-sitosterol with a share of 62.59-69.74%, stigmasterol with ashare of 12.13-15.00% and campesterol with a share of6.59-11.94% in total sterols. Fermentation and distilationprocesses, to which the seeds have been exposed, haveno effect on the content of phytosterols in grape seed oils.The paper has shown the negative influence of thefermentation and distillation process, to which the seedshave been exposed, onto the antiradical potential of theobtained oils. The antiradical potential of grape seed oilsdepends on grape varietes, as well as on the way oil isobtained (cold pressed or refined).Processes of fermentation and distillation also affect thebasic chemical quality of obtained cold pressed oils in sucha way as to increase the acid and peroxide values.Cold pressed grape seed oils show good oxidative stability. The Rancimat test showed differences in theinduction period of cold pressed grape seed oils as a resultof the variation in the variety, as well as in the method ofobtaining the seed. The fermentation process affects theincrease, and the process of distillation decreases theinduction period.Based on all the obtained results, it can be concludedthat cold pressed grape seed oils showed differentnutritional quality and oxidative stability due to specificdifferences resulting from differences in variety and seedorigin, i.e. due to the specific effect of fermentation anddistillation processes on the seeds from which the oil wasproduced, thus confirming the hypothesis.
Hesse, Uljana [Verfasser]. „Untersuchungen zur Endophytbesiedelung von Gräserökotypen und zu Symbioseeffekten durch Neotyphodium lolii in Lolium perenne-Genotypen hinsichtlich Stresstoleranz und Ertragsmerkmale / vorgelegt von Uljana Hesse“. 2002. http://d-nb.info/965087298/34.
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