Browsing by Subject "Most"

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Analysis of the effects of abolishment of planting rights in the European Union on the wine sector in Rheinland-Pfalz, Germany
(2016) Bogonos, Mariia; Dabbert, Stephan
The production and marketing of wine in the European Union (EU) are governed by the Common Market Organization (CMO) of the EU Common Agricultural Policy (CAP). Since 1976, a crucial point of the CMO with respect to wine has been the regulation of wine production by the system of the planting rights. Consistent with the goal of increasing the competitiveness of EU wine producers on the world market, the 2008 CAP reform included the liberalization of the planting rights regime by 2018 the latest. As a result of intense discussions on the EU and EU Member states levels, the planting rights system has recently been converted into a scheme of authorizations for vine plantings, which is valid until 2030. This dissertation investigates the effects of abolishment of planting rights on the largest wine-producing region in Germany, Rheinland-Pfalz. For this purpose a comparative static regional partial net-trade equilibrium model that includes the output of a Markov chain projection was used. The model simulates the future distribution of vineyards in Rheinland-Pfalz among wine farm groups according to size classes and area type, the demand for standard and basic quality wine must in Germany and production of standard and basic quality wine must in Rheinland-Pfalz. The policy simulation model was run for scenarios of different levels of market prices of wine must, different land rental prices, restricted and liberalized planting rights, and a scheme of authorizations for vine plantings. The results revealed that the effects of liberalization of planting rights and of a scheme of authorizations for vine plantings depend on profitability of standard and basic quality wine must production. In particular, if standard and basic quality wine must production is profitable for at least one wine farm group, and planting rights are liberalized, production of standard and basic quality wine must and, respectively, acreage of vineyards in Rheinland-Pfalz will increase with respect to the demand for these two types of wine must in Germany and availability of land suitable for vine growing. If production of basic and standard quality wine must is profitable and planting rights regime is retained or converted into a scheme of authorizations for vine plantings, the acreage of vineyards in Rheinland-Pfalz might reach the maximum defined by the policy regime. In addition, newly established vineyards will be used for production of either standard or basic quality wine must depending on which type is more profitable. Movement of vineyards within the wine farm groups will take place only if at least one of the farm groups receives positive economic profits. Land for vine growing will be distributed to the farm groups which are profitable and characterized by positive growth rates in the past. The abolishment of planting rights will have minor or no effects on the wine sector in Rheinland-Pfalz, if production of basic and standard quality wine must is not profitable. Similarly, movement of vineyards within the wine farm groups will not take place, if none of the farm groups receive positive economic profits. This dissertation provided an empirical examination of the effects of restricted and liberalized planting rights, as well as a scheme of authorizations for vine plantings on the wine sector in Rheinland-Pfalz. It has also supplemented the literature on how policy reforms with regard to the limitation of agricultural production input use in order to control the output affect the agricultural production sector.
Detektion von Schadhefen in Wein mittels mit Flusszytometrie analysierter in situ Hybridisierung (Flow-FISH)
(2021) Willberger, Ilka Nadine; Scharfenberger-Schmeer, Maren
In oenological practice, mostly unpasteurised grape musts are used. This leads to an increased introduction of non-saccharomyces, which can have a lasting effect on the fermentation process. Disturbances in the fermentation process are usually only detected in practice on the basis of abnormalities in selected parameters such as sugar content or temperature or the occurrence of off-flavours. The fermenting yeast population may already be so affected at this point that intervention in the fermentation process can no longer prevent the occurrence of off-flavours in the end product or incomplete fermentation. With the help of flow cytometry, an efficient method using FISH (Fluorescence In Situ Hybridisation) was developed to detect and quantify the common representatives of the fermentation population such as Sacchoromyces cerevisiae and the harmful yeast population such as Hanseniaspora uvarum, Dekkera bruxellensis and Pichia anomala in the course of fermentation. Rapid detection enables countermeasures to be taken in good time before a harmful yeast population can have too great of an influence on the course of fermentation and the metabolites formed. Flow-FISH was established with pure cultures from strain collections in defined medium (YPD) and pasteurised white grape must. Samples are extracted and fixated directly from fermentation mixtures. For hybridisation, 18S- and 26S-rRNA probes with FITC-labelling are used. For the evaluation of the flowcytometric data, the Overton-subtraction method is used in this work. This allows a more accurate assessment of the hybridised cell population than the usual setting of a marker. For this purpose, an effective negative control with complementary sequence to the universal eukaryote probe (Euk516) is introduced. Subsequently, the method already known from the literature was optimised with regard to hybridisation conditions and cell fixation and thus adapted to the requirements of a quantitative flow cytometric analysis. With fixation in formaldehyde or in ethanol, fixation methods were developed that fulfil the requirements of both rapid and reliable fixation in the laboratory and rapid fixation in the cellar, if transport to the laboratory is not possible in a timely manner.Helper probes were designed to increase the fluorescence intensity. They are unlabelled and bind in the direct proximity of the specific probe. In all yeast species investigated, S. cerevisiae, H. uvarum, D. bruxellensis and P. anomala, the fluorescence intensity can be considerably increased by using the helper probes. In the case of D. bruxellensis and P. anomala, detection is only possible with the use of the helper probes. The helper probes allow the Flow-FISH assay to be used in a broader growth range of the yeast culture. Without helper probes, quantitative detection is limited to the middle logarithmic growth phase. With helper probes, hybridised cells can be reliably detected starting in the early logarithmic growth phase up until the stationary phase. This covers the critical phase of fermentative activity so that increasing contamination can be detected in the fermentation.The specificity of the probes is given. In part, there are slightly increased fluorescence intensities compared to the negative control, especially with the D. bruxellensis probe combination and non-specific yeasts, which can probably be attributed to increased binding due to the composition of this probe combination.The Flow-FISH assay is also reliable in mixtures of different yeast species and up to a cell count of 10³ cells / ml in the initial fermentation. This detection limit is also achieved by other methods in molecular biology for yeast detection. In contrast to most of these methods, Flow-FISH can also quantify the number of yeasts present. Additionally the use of the flow cytometer offers a simple variant to determine the total cell count of all yeasts in the fermentation. The detection limit of Flow-FISH allows detection before the damage threshold values of the yeasts examined are reached. The Flow-FISH method presented in this dissertation can also be applied to other yeast strains, some of which also originate from wild isolates. A transferability to native fermentations from oenological practice is given. It was possible to examine both spontaneous fermentations and inoculated fermentations in practice fermentations in steel tanks for their yeast population composition and to follow their development in the course of fermentation. Due to the use of flow cytometry and the helper probes and negative control used in this dissertation, the optimised Flow-FISH assay offers a stable basis for the continued development of a test system for use in oenological practice.
UV-C-Behandlung von Traubenmost zur Inaktivierung von Mikroorganismen
(2018) Diesler, Kathrin; Scharfenberger-Schmeer, Maren
The development of new preservation process techniques to protect ingredients and maintain a high quality standard is always a main goal in the food industry. In course of this, microbial safety has top priority. UV-C technology is a modern, non-thermal process with high efficiency. It has been used for sterilization and treatment of drinking water for many years. Also, ultraviolet radiation for disinfection purposes is already being used in other areas of food production. To what extent this method can be successfully applied in the field of grape must production, will be investigated in this dissertation. For this purpose, several yeasts and bacteria, relevant in this area, were examined for their inactivation potential by UV-C treatment. To ensure the best possible microbial inactivation in must, it is essential to determine an ideal treatment dose for both yeasts and bacteria. The results have confirmed that bacteria are far more sensitive to UV C treatment, than yeasts. It was also shown that there are major differences in UV-C stability within the seven yeast species and six bacteria species used in this study. The analyses have identified Metschnikowia pulcherrima and Acetobacter aceti as the most UV-C stable and Brettanomyces custerianus and Pediococcus sp. as the most sensitive organisms. Furthermore, three morphologically different Brettanomyces strains were used to show that there are also strain-specific variances in the response to UV-C treatment. Using Saccharomyces cerevisiae as an example, a potential formation of UV-C resistance was also ruled out. For this purpose, yeast cells were exposed to a dose, that did not result in complete inactivation. The surviving cells were cultured and retreated. Even after repeating this process eight times, no change in the UV-C response of the yeast cells could be detected. For the application of UV-C technology in the juice and wine industry it has to be ensured, that microorganisms are killed directly and their enzymatic activities are directly inhibited. Yeasts and bacteria could further convert sugar to alcohol or form unwanted metabolic byproducts. Therefore, the enzymatic activity after the initial treatment and during the inactivation process of Saccharomyces cerevisiae was analyzed in more detail. HPLC was used to determine the content of glucose, fructose and ethanol. No enzymatic activity could be detected in the UV-C treated samples from the moment after the initial UV-C treatment, up to the day of complete destruction. However, the effectiveness of UV-C treatment of must and wine cannot be attributed solely to the responsiveness of the various microorganisms. Other product parameters such as grape variety, turbidity and optical density also play a decisive role. In this context, four different musts with different optical density and turbidity were treated and the inactivation kinetics of Saccharomyces cerevisiae were compared. In this work it could be proved, that with an increasing optical density and a higher turbidity, the efficiency of the UV-C treatment in must decreases strongly. The success of a treatment is also directly dependent on the initial contamination rate of the product. Tests with different starting cell numbers have shown, that the required inactivation dose also has to be increased, as the number of cells increases. In the winemaking process, however, not only yeasts and bacteria can be a potential source of danger. The fungal infection of grapes by Botrytis cinerea also carries a high risk. The polyphenol oxidase laccase, produced by the fungus, damages ingredients and leads to a colour change in must and wine. In the investigations it could be proven, that it is possible to strongly reduce or completely inactivate the enzymatic activity in Botrytis infected must, depending on the starting concentration. In summary, UV-C technology represents an effective alternative and extension for current oenological practice. It offers the possibility to inactivate a large number of wine relevant microorganisms without causing resistance. In addition, this work has created a new framework for the application of must specific parameters. The results for the inactivation of the enzyme laccase are also proved to be extremely promising.