Thesis (doctoral)--Münster, 1983.

This thesis is concerned with the formation of carbonyl compounds in wine, depending on the spread of wine. Therefore examines what influences the spread of musts and wines on the formation of carbonyl compounds. Discusses the characteristics and forms of sulfur dioxide. Further detail the carbonyl compounds which bind just with sulfur dioxide. In this work it was found that the influence of the spread of the wine has no great influence formation of carbonyl compounds. On the contrary, it was confirmed that the initial SO2 concentration in the must greatly affects the formation of acetaldehyde, which binds sulfur dioxide. Furthermore ratified the greater influence on the formation of carbonyl compounds, the activity of microorganisms in the wine than different concentrations of SO2.

Techn. Hochsch., Diss., 2003--Aachen.

The thesis focuse on the effect of dose levels of sulfur dioxide in the must on the formation of carbonyl compounds. Futhermore it is concerned with oenological properties of sulfur dioxide, its forms and effects on wine. The thesis corroborates in detail carbonyl compounds bind sulfur dioxide and discusses their origin and various options to affect their quantity. Substances that may partially replace sulfur dioxide and thereby reduce its total quantity in wine are also debated. Experimental part of the thesis involved samples of wine differing in quantity of sulfur dioxide added to the must before fermentation and in forms of nutrition. Using the HPLC analysis concentrations of acetaldehyde, pyruvic acid, and 2-oxoglutaric acid were determined. The experiment demonstrated the effect of initial doses of sulfur dioxide on the amount of generated acetaldehyde and pyruvic acid. The effect of addition of thiamine, which reduces formation of pyruvic acid, was also shown.

Öl är en dryck som i ökande grad framställs av mindre bryggerier. För bryggarna är ett av målen att producera öl med så lång hållbarhet och en så jämn kvalitet som det är möjligt utifrån resurser, ekonomi och engagemang. En av svårigheterna vid ölbryggning är oönskad förekomst av syre efter jäsning. Syre i produkten kan förstöra ölets karaktär och ge upphov till oönskade smakämnen. Det här projektet har handlat om att mäta koncentrationen löst syre(O2) i öl efter filtrering med kiselgur och med några olika metoder försöka minimera syreupptag under filtreringsprocessen. Detta för att säkerställa god kvalitet på Nils Oscars öl. Resultatet visar på att det finns skillnad i syrekoncentrationen i alla ölsorter när metoderna med kallt- och varmt förträngningsvatten har använts samt när koldioxidgenombubblingen tillförts i kiselgurublandaren. Det skulle behöva ses över på andra delar av bryggeriprocessen för att utesluta syrekontakt med öl genom att kontrollera ventiler, rör, ledningar för att försäkra sig om att syretillförsel inte sker. Det finns också åtgärder under filtreringen som skulle behöva förbättras. Om varmare vatten används i produktionen och koldioxid tillsätts i kiselgurblandaren kommer det att minska syrekoncentrationen i filtrerad öl. / Beer is a drink that increasingly is produced in smaller brewers. For the brewers the most important is to make the beer long lasting, and that requires resources, economy and commitment. Many things can go wrong when making beer, and one concern is the oxygen levels in beer that can change its taste and character and produce off flavors that are not wanted in the product. In this project the levels of oxygen was measured in the beer after filtration with kisel- gur, and using different methods attempting to minimize oxygen uptake during the filtering process to insure a good quality of Nils Oscars beer. The results showed that there are differences in oxygen levels between all beer types when using the three methods with cold- and hot water as a narrowing water and using carbon dioxide in the kiselgur mixer. It would be necessary to lock at other parts of the brewing process to exclude oxygen contact with beer. By ensuring valves, pipes and lines, quality of the equipment, and exclude any contact with oxygen. There are workarounds during filtration that can be improved. Like using hot water for a longer time. It would also need a stable and prolonged solution for induction of carbon dioxide to bubble in the kiselgur mixer. The induction of carbon dioxide has been shown to minimize oxygen pick up in filtrated beer.

Dissertation thesis Study of physical chemical features in fruits of peaches and plums was developed at the Institute of Post Harvest Technology of Horticulture Products at Faculty of Horticulture of Mendel University in Brno. This thesis concentrated on setting of material elements in fruits of peaches, the variety 'Red Haven' in the period of ripening and post-harvest storage in different types of atmosphere according to contents of CO2 and O2. In five analysed varieties of peaches 'Flamingo', 'Harbele', 'Harblaze', 'Harbrite', and 'Maria Marta' were set ripening values during ripening on tree. In varieties of plum fruits 'Valjevka', 'President', 'Stanley' was found their tolerance against gas mixtures. During ripening of peach varieties were set volatile elements (ethanol, acetaldehyde) and was stated the concentration of ethylene in the critical period of ripening. In literary review there are characterized material elements of pulp fruits, both chemical structure of fruits, and volatile aromatic substances and their biogenesis, there are described in detail material substances of fruits, amongst which belong biological, physical, sensory, technological signs of quality and post harvest influences on fruits. Further ethylene is characterized in post-harvest period and its physiological features and methods of its effect limitation, factors of plant reaction against ethylene, and chemical inhibition of ethylene reception. Next part deals with methods of quality evaluation and techniques of fruit storage, further on with fruits of plums, peaches and their general characteristics. Experimental part evaluates several fractional methodics. Assessment of peach varieties in three stages of ripening and setting of ripening index, influence of low content of oxygen on production of anaerobic metabolites and volatile materials stated in plum fruits, distribution of frequency of peach fruits ripening on tree in five stages of ripening, production of ethylene according to the grades of ripening in peach varieties, their sensory evaluation and setting of volatile aromatic compounds. In variety 'Red Haven' there were evaluated grades of ripening in the range: unripe to over ripe, which represented in dates five successive harvests. Each successive term was compiled of 40 fruits of average weight for the set grade of ripening. Production of ethylene was evaluated through distribution of fruits in settled harvest date, and was distinctively different in fruit distribution according to ethylene content pursuant to harvest date. In executed measurements of fruits of peach variety 'Red Haven' ripening on tree in grades of ripening unripe, ripe, over ripe, in their frequency five to seven there was stated concentration of ethanol and acetaldehyde expressed in mg*l-1 by direct spraying of juice into filling analytic colon. Concentration of acetaldehyde did not change during fruit ripening, and this metabolite can be assessed as interim which changed by alcohol dehydrogenase into ethanol. Concentration of ethanol in over ripe fruits is characteristic with higher content which does not represent multiple concentrations in over ripening in common oxygenated atmosphere. Evaluation was executed only in one variety, however, similar tendencies should be supposed in other varieties as well. Index of ripening (IZ = RS* strength/TK) was formulated in five peach varieties, which represents processes of fruit ripening on tree and important differences were found for ripe and unripe fruits, whereas index of ripening between ripe and over-ripe fruits differs only in several units. With following ripening rates in varieties there were determined differences in phases unripe to ripe for varieties 'Harblaze' and 'Maria Marta'. Furthermore these varieties were evaluated by sensory analysis as well. In analytical method HP/GC/MS 42 volatile aromatic compounds were specified in groups of alcohols, aldehydes, esters, terpenes, lactones, and organic acids in plum fruits in varieties 'Valjevka' and 'Stanley'. In Tukey´s test productions of each specified volatile compounds were evaluated. In variety 'Red Haven' treated with four different gas mixtures (ULO, CA, RA, FAN) according to percentage of content of set amount of CO2 and O2, and stored in these atmospheres during 29 days, there were specified several volatile aromatic materials through analytical method HP/GC/MS.