For my bachelor's project, I am confronting the feelings of being transnationally adopted. I do not see adoption as a ”win-win” situation, and I would like people to both think critically about it and question its glorification. As a POC-child myself who grew up with white parents, colorblindness has made my existence rather difficult to deal with. Plagued with feelings I did not understand at the time, I became an isolated island. I want to visualize the feeling of estrangement and alienation from your own body and frightened to drown in your own skin. I have often felt the need to unzip my skin suit and to leave it in a pile on the floor, next to my trousers. In this project I am growing my own skin in a vat, or more precisely, I am growing a kombucha culture in tea and sugar. During the fermentation process, the kombucha culture creates a cellulose material that resembles human flesh. The process is slow, and the development of the material requires a lot of love and nutrition. In return, I get a self-produced material that allows me to work independently. My final piece communicates how it feels to not feel compatible with the body that encases you, as a result of the norms that are written onto your skin.

As the global plastic consumption is increasing, an innovative substitute for petroleum-based product must be developed towards a more sustainable society. Cellulose is the most abundant biopolymer on earth having potential because of its biodegradability and is produced from renewable resources. However, purification of plant cellulose is costly and limit the application development where bacterial cellulose have gained more focus. Bacterial cellulose can be obtained as a by-product from Kombucha fermentation on commercial sugars such as sucrose. Replacing commercial sugars with molasses, a by-product from the sugarcane industry, as a substrate could be a low-cost alternative. The purpose of the study is to investigate and evaluate the properties of bacterial cellulose obtained from Kombucha microorganisms fermented in molasses medium using different fermenting conditions. Biofilms containing bacterial cellulose were obtained by fermenting with three types of molasses inoculated with two types of Kombucha cultures. Two of the three molasses used came from PT. Andalan Furnindo in Indonesia from two different sugar production batches and one type from Nordic Sugar AB in Sweden. The culture was obtained from previously fermented Kombucha, one from Tujju Kombucha, Indonesia and one from Roots AB, Sweden. Fermentation was carried out with one of the molasses from PT. Andalan Furnindo together with coffee waste, containing different concentrations of the substrates. The obtained biofilms were compared to biofilms produced with the ingredients of a conventional Kombucha setup. The other molasses from PT. Andalan Furnindo was fermented with or without the addition of pure caffeine, using culture with adapted microorganisms. Obtained films were either dried under pressure, without pressure in oven or purified with 1 M NaOH and air-dried. Optimum fermentation conditions with the molasses from Nordic Sugar AB were analysed. Regarding the fermentation with molasses from PT. Andalan Furnindo and coffee waste, the highest yield of biomass after fermentation could be seen in the system containing the highest amount of total sugars (100 g/l) and highest amount of caffeine deriving from coffee waste (200 mg/l). However, the membrane produced from conventional Kombucha exhibited a more flexible character, having superior elongation at break, stretching 46 % more than the sample produced in molasses medium. Using culture with adapted microorganisms in the fermentation with molasses from PT. Andalan Furnindo proved to increase the biomass yield with roughly 40 % compared to the biofilms produced without adapted microorganisms, but no effect of higher caffeine concentration was detected for the setups. All biofilms obtained from fermenting with adapted culture possessed superior mechanical-thermal properties. The highest elongation at break of 48.7 % was observed for the sample dried under normal conditions and the highest tensile strength was observed for the purified samples of 43.5 MPa. Furthermore, the purified samples possessed a higher thermal stability and had the highest cellulose content of 64 %. Adaptation was vital to obtain any bacterial cellulose fermenting in medium containing molasses from Nordic Sugar AB.

The kombucha drink is referred to as leavened tea with added sponge called a scobie. In this way, a low-alcohol beverage is obtained, which gains considerable popularity, especially due to the alleged beneficial properties for human health. The microbial composition of this beverage is very rich, consisting of bacteria and yeasts living in a beneficial symbiosis [11]. The microbial composition of the drink and its beneficial effects on human health are very closely related. This work deals with the analysis of the chemical composition of the commodity beverage, especially with regard to the content of major components such as organic acids, carbohydrates and ethanol. These analytes are among the most common and most profoundly found substances in the carbohydrate beverage and are very closely related to the microbial composition of the scoby itself [3]. Combo beverage samples were supplied by RebornFood, one of which is the commercial production of this drink on the Czech market. At the same time, this company bases itself on purely natural fermentation of beverages, and therefore it is not particularly involved in the production process. The results of this diploma work point to the effect of the scoby used and the associated occurrence of analytes in the beverage, as well as the production process associated with the formation of analytes, which is described in several articles. It is expected that this work will provide information both on the production conditions and on the chemical properties of the beverage related to the condition of the scoby, which will be used further, both for RebornFood and the material used to solve the technical problems of this beverage production.

Denna kandidatuppsats undersöker framtagningen av ett bakteriellt cellulosamaterial (BC-material), samt undersöker om materialets vattenavvisande egenskaper kan förbättras för att kunna möjliggöra användning som textilt material. Arbetet grundar sig i det faktum att BC- materialet är av en hydrofil karaktär, något som den brittiska designern Suzanne Lee utryckt vara ett problem för dess användningsmöjligheter. Arbetet behandlar en litteraturstudie av BC, vilken ligger till grund för en experimentel del där odling, vattenavvisande beredningar och vattenavvisande tester utförts. Gällande BC-produktion och materialframtagning har faktorer som pH-värde, temperaturförhållanden, och recept visat sig påverka cellulosaproduktionen. Ett varmare temperaturförhållande på 30°C jämfört med rumstemperatur (20- 22°C) har uppvisat bättre cellulosatillväxt. Detsamma gäller även för användandet av äppelcidervinäger i odlingmediumet, vilket uppvisat positiva resultat. Testerna av det framtagna BC-membranet har för det första kunnat bekräfta dess påstådda hydrofilitet. Vidare har även de vattenavvisande behandlingarna visat positiva resultat, även om användarmöjligheterna för materialet fortfarande anses vara begränsade inom det textila området. En ökning av kontaktvinkeln från 40,76° till 96,98° uppvisades efter att en behandling med en syntetisk vaxpolymer applicerats. Denna ökning på drygt 100 % skapade en kontaktvinkel över 90°, vilket teoretiskt betyder att materialets karaktär gått från hydrofilt till hydrofobt. Ett likvärdigt resultat uppvisades även efter en behandling med en vaxdendrimer. Materialet uppvisade dock tydliga resultat på att absorbera vatten vid längre tid av blötläggning, oavsett om det behandlats eller ej. / This bachelor thesis is investigating the development of a material based on bacterial cellulose (BC), as well as examine and test the material's hydrophobic properties. This is made in order to improve its user possibilities as a textile material. The motive is based on the fact that BC- materials have a hydrophilic nature, something that the British designer Suzanne Lee expressed as a problem for its user possibilities. The thesis process a literature study of BC, which is used for an experimental study where cultivation, water repellent treatments and water repellent tests are performed. Regarding BC-production and material creation, factors as pH-levels, temperature conditions and the recipes has shown to affect the cellulose production. The cellulose levels occurred to increase during a warmer condition at 30 °C compared to room temperature (20-22°C), both conditions where used for the cultivation. The same positive results also occurred when apple cider vinegar was used in the cultivation bath. The tests on the developed BC-membrane, initially confirmed its alleged hydrophilic nature. Furthermore, positive results occurred for the water repellant-treated materials, even if the user possibilities still is considered to be limited in the textile field. The contact angle increased from 40.76 ° to 96.98 ° on the material treated with a synthetic wax polymer, which results in a 100% increase. The angle of 90°, theoretically means that the character of the material changed from hydrophilic to hydrophobic. Similar results also occurred after treatment with a wax dendrimer. The material, however, showed significant results in absorbing water when subjected for a longer time of soaking, whether it was treated or not.

<p>Promene komponenata i strukture mleka ispitane su tokom fermentacije kori&scaron;ćenjem inokuluma kombuhe kultivisane na crnom čaju zaslađenom saharozom<br />u koncentraciji 10%. Fermentacija mleka sa 2,2% mlečne masti izvr&scaron;ena je na dve različite temperature (37&deg;C i 42&deg;C) i uzorci su analizirani na sledećim pH vrednostima: 6,1; 5,8; 5,4; 5,1; 4,8 i 4,6. Urađena je determinacija i identifikacija produkata fermentacije laktoze kao &scaron;to su: &scaron;ećeri, organske kiseline i masne kiseline. Ispitane su teksturalne i reolo&scaron;ke karakteristike i mikrostruktura uzoraka. Pored toga, utvrđene su sličnosti i razlike uticaja inokuluma kombuhe na proces fermentacije mleka u poređenju sa delovanjem jogurtne, odnosno probiotske starter kulture.<br />Tokom fermentacije mleka u različitim fazama procesa pri odabranim pH vrednostima na 42&deg;C transformi&scaron;e se 14,6% laktoze odnosno 18,2% na 37&deg;C. Sadržaj galaktoze i glukoze koje nastaju fermentacijom i hidrolizom laktoze raste između prve i druge tačke fermentacije (pH=6,07 i pH=5,8). Dominantne organske kiseline tokom fermentacije su L&ndash;mlečna kiselina i sirćetna kiselina. Nije utvrđena značajna razlika u sadržaju masnih kiselina tokom fermentacije mleka kombuhom na 37&deg;C i 42&deg;C. Sadržaj palmitinske kiseline u mleku i uzorcima tokom fermentacije je najveći, zatim slede miristinska, stearinska i oleinska kiselina.<br />Praćenjem procesa fermentacije mleka uz primenu kombuhe na 37&deg;C i 42&deg;C od početne pH vrednosti 6,07 do zavr&scaron;ne 4,6, najznačajnije promene teksturalnih karakteristika (čvrstoće, konzistencije, kohezivnosti i indeksa viskoziteta) i reolo&scaron;kih svojstava zabeležene su između pH=5,4 i 5,1, &scaron;to je u korelaciji sa mikrostrukturom.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Promene viskoziteta u svim uzorcima pokazuju istu regresionu liniju, sa različitim koeficijentima i visokom vredno&scaron;ću r2, osim uzorka proizvedenog primenom jogurtne kulture na pH 5,4. Uzorak dobijen kori&scaron;ćenjem inokuluma kombuhe imao je najveće vrednosti kompleksnog modula, &scaron;to je rezultiralo boljim reolo&scaron;kim karakteristikama gotovog proizvoda.<br />Da bi se definisao empirijski model procesa fermentacije laktoze u mleku delovanjem kombuhe formulisana su prethodno dva matematička modela za kinetiku fermentacije saharoze u tradicionalnom kombuha napitku (na crnom čaju) &ndash; jedan koji opisuje promenu koncentracije saharoze tokom fermentacije, i drugi koji opisuje brzinu fermentacije. Promena koncentracije laktoze na ispitivanim temperaturama 37&deg;C i 42&deg;C sastoji se od dve lag faze između kojih je faza izraženog pada koncentracije. Krive zasićenja pokazuju sigmoidalnu kinetiku na nižim koncentracijama laktoze, ukazujući na kompleksni ne&ndash;Michaelis&ndash;Mentenov tip kinetike.<br />Generalno može se istaći da su primenom inokuluma kombuhe tokom fermentacije mleka u različitim fazama procesa ustanovljene specifične promene komponenata i strukture u poređenju sa efektima delovanja jogurtne odnosno probiotske starter kulture.</p><p>&nbsp;</p> / <p>Changes of milk components and structure were examined during fermentation by kombucha inoculum cultivated on black tea switened with saccharose in a concentration of 10%. The fermentation of milk with 2.2% of milk fat was carried out at two different temperatures (37&deg;C i 42&deg;C) and samples were analyzed at the following pH values: 6.1; 5.8; 5,4; 5.1; 4.8 and 4.6. Determination and identification of the lactose fermentation products, such as: sugars, organic acids and fatty acids were carried out. Textural and rheological characteristics and microstructure of the samples were investigated. Furthermore, the effect of kombucha on the milk fermentation process was compared with the effect of yoghurt and probiotic starter culture.<br />During milk fermentation at various stages of the process 14.6% of lactose content was transformed at 42&deg;C and 18.2% at 37&deg; C. The galactose and glucose content, which are formed by lactose hydrolyses and fermentation, increased between first and second pH point of fermentation (pH = 6.07 and pH = 5.8). Dominant organic acids during fermentation are L&ndash;lactic acid and acetic acid. There is no significant difference between samples in fatty acids content during fermentation on 37&deg;C and 42&deg;C. The level of palmitic acid in milk and samples was the highest of all fatty acids, followed by myristic, stearic, and oleic acid.<br />The most significant changes in textural properties (firmness, consistency, cohesiveness and viscosity index) and viscosity during milk fermentation by kombucha at 37&ordm;C and 42&deg;C, from the initial pH value 6.07 to a final 4.6, were recorded between pH=5.4 and 5.1, which is in correlation with microstructure.<br />Viscosity changes in all samples showed the same regression line with the different coefficients and a rather high r2 except for the sample produced with standard yoghurt culture at the pH 5.4. Samples produced with kombucha had the highest values of the complex modulus, which indicates better rheological characteristics of the final product.<br />In order to define an empirical model of lactose fermentation process in milk by kombucha, two mathematical models (one for the change of saccharose concentration, during its fermentation by kombucha, and the other for the rate of the mentioned fermentation) previously were formulated. Change of lactose concentrations at 37&ordm;C and 42&ordm;C consists of two retaining stages and very steep descend in-between. Saturation curves show a sigmoidal kinetics at low lactose concentrations, indicating a complex non&ndash;Michaelis&ndash;Menten type kinetics.<br />Generally it can be concluded that specific changes in the components and structure of milk by application of kombucha inoculum during fermentation at different stages of the process were established in comparison with the effects of yoghurt and probiotic starter culture.</p>

Kombucha is a fermented tea beverage consumed for its probiotics and functional properties and has a unique sensory profile driven by the properties of tea polyphenols and fermentation products, including organic acids. Fermentation temperature and sucrose content affect the fermentation process and the production of organic acids, yet less is known about the impact on the sensory profile and consumer acceptance. Thus, we aim to examine the impact of sucrose concentration and fermentation temperature on sensory attributes and liking. For this study, kombucha tea was fermented at three different concentrations of sucrose and fermented at two temperatures for 11 days. Fermentation was monitored by pH, brix, and titratable acidity, and consumers (n=104) evaluated the kombucha for sensory attributes and overall liking. Fermentation temperature resulted in significant differences in titratable acidity, with higher temperatures producing more organic acids, resulting in higher astringency, and suppressed sweetness. The lower fermentation was reported as significantly more liked, with no difference in liking between the 7.5% and 10% sucrose kombucha samples. Overall, sucrose concentration had less of an impact on overall liking, and the sensory profile and fermentation temperature, which drives the fermentation rate and production of organic acids, strongly influenced the sensory profile.

Examensarbetet har utförts tillsammans med ett företag som tillverkar ekologisk kombucha. Företaget var intresserade av att ta reda på om just ekologisk kombucha är den fortsatta vägen framåt, då smakutbudet på kombuchan begränsas av tillgången på ekologiska fruktjuicer. Att efterfrågan på ekologiska livsmedel minskat under de senaste åren var ytterligare ett incitament att undersöka problemet. Studiens syfte var därför att leverera ett utlåtande om produktegenskapen ekologisk är den fortsatta vägen framåt avseende betydelsen för kundnöjdhet. För att uppfylla syftet användes en särskild metod inom mätning av kundnöjdhet inspirerad av Kano-modellen, där konsumenter tillfrågades om deras inställning till vissa nuvarande eller potentiella produktegenskaper hos kombuchan. Studiens resultat visar att olika kundgrupper värderar och prioriterar produktegenskaper annorlunda. De flesta av produktegenskaperna uppfyller dock omedvetna kundbehov vilket visar på att den undersökta organisationen har en god möjlighet att sticka ut på marknaden och vara konkurrenskraftiga. Produktegenskapen ekologisk är inte lika viktig att inkludera som producerad i Sverige, men kan fortsättningsvis inkluderas i kombuchan då ett stort smakutbud och ett lägre pris varken är förväntade eller nödvändiga egenskaper. Att inte inkludera ekologisk har även en mycket större påverkan på missnöjdheten hos kunderna än att inte inkludera ett större smakutbud. De implementeringsförslag som presenteras i studien är bland annat vikten av att undersöka möjligheten att producera kombuchan i Sverige, fortsätta mäta kundnöjdhet, se över hur vissa egenskaper synliggörs på produktens flaska samt undersöka om endast en del av sortimentet kan vara ekologiskt. Genom att beakta dessa förslag kan företaget uppfylla deras kunders behov ytterligare. / This thesis was conducted in collaboration with a company that manufactures organic kombucha. The company wanted to know whether organic kombucha is the way forward, as the flavour range of their kombucha is limited due to the availability of organic fruit juices. The decreasing demand for organic foods was an additional incentive to research the issue. The purpose of the study was therefore to deliver an opinion on whether the product attribute organic is the way forward, in terms of its significance for customer satisfaction. To do that, a method within the customer satisfaction measurement field inspired by the Kano model was used, where consumers were asked about their attitudes toward current and potential product attributes. The study’s results show that different customer groups value and prioritize attributes differently. However, most of the attributes meet unconscious customer needs which indicates that the company has a good opportunity to stand out. Although the attribute ’organic’ is not as important to include as ’produced in Sweden’, it may remain since a wide flavour range and a lower price are neither must-be nor one-dimensional attributes. Also, not including ’organic’ has a much greater impact on customer dissatisfaction than not including a wider range of flavours. Proposals for implementation include investigating the possibility of producing the kombucha in Sweden, continuous customer satisfaction measurement, reviewing the visibility of the product’s labels and examining if only some flavours in the range can be organic. By considering these proposals, the company could further meet their customers’ needs.

Different factors such as growing environmental awareness due to the increasing negative impact of persistent plastic wastes, the uncontrollable price variations of the raw material and the rapid depletion of  reserves have increased the interest in research regarding polymers derived from renewable sources to replace petroleum-based materials. One of the earth’s most abundant macromolecules is cellulose. The production of cellulose from another resource replaces and reduces the demand from plants, the other resource being cellulose from a bacterial system. Bcaterial cellulose film were produced by fermenting apple waste (apple pomace) from cider production donated by Herrljunga Cider in Herrljunga, Sweden and expired fruit juice, produced by LoveJuice Indonesia, containing a mixture of fruits, mainly apple. As inoculum for the fermentations two different Kombucha cultures were used. To optimize the fermentation conditions, factors such as nitrogen source, sugar content, temperature, pH, surface area, sterilization of the substrate, culture condition and fermentation time was varied to obtain the desired result. The bacterial cellulose films were dried at 50-70 °C in an oven, air-dried or freeze-dried to evaluate the impact of drying technique on the final material. The behavior of the microorganism during fermentation was monitored by sampling and observation. The consumption rate of carbohydrates was analyzed using high performance liquid chromatography (HPLC). The properties of the obtained biofilms were analyzed using thermogravimetric analysis (TGA), tensile testing and determination of cellulose content in the obtained biofilms. Two different sugar concentrations (35 g/l and 70 g/l) and three different caffeine concentrations (0 g/l, 150 g/l and 225 g/l) as nitrogen source were investigated to determine the best condition. A control batch of conventional (black tea and 70 g/l table sugar) Kombucha was used as reference. The highest tensile strength (50 MPa) and thermal stability was observed in the biofilms with the highest yield that had been dried in oven. The biofilms obtained by fermenting apple pomace from the cider industry showed the highest tensile strength and highest thermal stability in comparison to fermenting expired fruit juice. The biofilm obtained by fermenting apple waste(sugar concentration 70 g/l) in combination with sterilizing the substrate without adding any nitrogen source, dried in an oven and purified using 0,1 M NaOH resulted in the highest tensile strength, highest thermal stability and the purest biofilm from a visual aspect. The highest yield was observed in the fermentation of apple pomace (sugar concentration 70 g/l) from the cider industry without sterilization of the initial media with an addition of nitrogen of approximately 450 mg/l). The optimal fermentation period was observed to be 14-15 days, at 25-28 °C under static conditions using a glass vessel with a diameter of 20 cm and an initial pH of 5,5.

<p>Kombuha je tradicionalni napitak koji se dobija fermentacijom zaslađenog crnog<br />ili zelenog čaja, fiziolo&scaron;kom aktivno&scaron;ću čajne gljive, koja predstavlja simbiozu<br />autohthonih vrsta kvasaca i bakterija sirćetnog vrenja. Cilj rada je bio da se ispita<br />biolo&scaron;ka aktivnost konzumnih kombuha napitaka (titrabilne kiselosti 3,5-4 g/L) od<br />crnog čaja (<em>Camellia sinensis</em> L), čaja ehinacee (<em>Echinacea purpurea</em> L.) i<br />rtanjskog čaja (<em>Satureja montana</em> L.). Za ispitivanje antimikrobne aktivnosti<br />kombuha napitaka upotrebljeni su sledeći sojevi bakterija, kvasaca i plesni:<br /><em>Pseudomonas aeruginosa</em>, <em>Staphylococcus aureus</em>, <em>Bacillus sp.</em>, <em>Salmonella<br />enteritidis, Proteus mirabilis, Escherichia coli, Sarcina lutea, Saccharomyces<br />cerevisiae, Candida pseudotropicalis, Rhodotorula sp., Penicillium<br />aurantiogriseum, Aspergillus niger i Aspergillus flavus</em>. Antioksidativna aktivnost<br />kombuha napitaka ispitana je na DPPH i OH radikale ESR spektralnom metodom.<br />Antiproliferativna aktivnost čajeva i kombuha napitaka od crnog i rtanjskog čaja<br />ispitana na tri ćelijske linije humanih karcinoma: HeLa (epitelni karcinom<br />cerviksa), MCF-7 (adenokarcinom dojke) i HT-29 (adenokarcinom debelog<br />creva). Pored istraživanja biolo&scaron;ke aktivnosti kombuha napitaka, cilj rada je bio da<br />se ispitaju i neki od osnovnih parametara kombuha fermentacije &ndash; optimalna<br />količina izvora ugljenika i azota u medijumu za kultivaciju, geometrijske<br />karakteristike fermentora, inokulacija starter kulturama. Definisanje kritičnih<br />parametara kombuha fermentacije je bio osnov za izvođenje matematičkog<br />modela za scale-up fermentativnog procesa.</p> / <p>Kombucha is a traditional beverage obtained by fermenting sweetned black or<br />green tea with tea fungus, which represents a symbiotic combination of acetic acid<br />bacteria and autochthonous yeast species. In this study, the antimicrobial,<br />antioxidative and antiproliferative activity of kombucha beverages (titratable<br />acidity 3,5-4 g/L) obtain from black tea (<em>Camellia sinensis</em> L), echinacea tea<br />(<em>Echinacea purpurea</em> L.) and rtanj tea (<em>Satureja montana</em> L.) were tested.<br /><em>Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus sp., Salmonella<br />enteritidis, Proteus mirabilis, Escherichia coli, Sarcina lutea, Saccharomyces<br />cerevisiae, Candida pseudotropicalis, Rhodotorula sp., Penicillium<br />aurantiogriseum, Aspergillus niger i Aspergillus flavus</em> were used as test<br />microorganisms for examination of antimicrobial activity. The antioxidant activity<br />of differently prepared kombucha beverages was examined agains DPPH and OH<br />radicals by ESR-spectrometry. Antiproliferative activity of black tea kombucha<br />and Satureja montana kokmbucka was measured by sulforhodamine B<br />colorimetric assay on HeLa (cervix epitheloid carcinoma), HT-29 (colon<br />adenocarcinoma), and MCF-7 (breast adenocarcinoma) cells line. Also, same<br />parametars of kombucha fermentation &ndash; optimal quantity of source of carbon and<br />nitrogen in cultivation medium, geometric characteristics of reactors and<br />inoculation by starter culture &ndash; were tested. Definition of critical parameters of<br />kombucha fermentation is important for derivation of mathematical model for<br />scaling-up fermentation process.</p>

The aim of this diploma thesis is to optimize a method of interfacial rheology for testing the interfacial behaviour of biofilms on the liquid-air interface and after that use the method for studying the biofilm formation under optimal and stress conditions. For studying the biofilm formation, Kombucha was used. It is a microbial culture forming a cellulose biofilm on the interface. As the stress conditions, reduction of sucrose concentration, change of pH and change of ionic strength was used. Next, the ability of regeneration of biofilm formed on the interface was studied. The biofilm formation was occured in all cases except of increasing ionic strength. As expected, the best biofilm biofilm growth was observed under optimal condition, which means a sucrose concentration 100 g/l.