Timing of di-ammonium phosphate addition to fermenting chardonnay must : effect on nitrogen utilization, ethyl-carbamate formation, and CAR1 expression by yeast /

The maximum amount of ethyl carbamate (EC), a known animal carcinogen produced by the reaction of urea and ethanol, allowed in alcoholic beverages is regulated by legislation in many countries. Wine yeast produce urea by the metabolism of arginine, the predominant assimilable amino acid in must. This action is due to arginase (encoded by CARl). Regulation of CARl, and other genes in this pathway, is often attributed to a well-documented phenomenon known as nitrogen catabolite repression. The effect of the timing of di-ammonium phosphate (DAP) additions on the nitrogen utilization, regulation of CARl, and EC production was investigated. A correlation was found between the timing of DAP addition and the utilization of nitrogen. When DAP was added earlier in the fermentations, less amino nitrogen and more ammonia nitrogen was sequestered from the media by the cells. It was also seen that early DAP addition led to more total nitrogen being used, with a maximal difference of ~25% between fermentations where no DAP was added versus addition at the start of the fermentation. The effect of the timing ofDAP addition on the expression of CARJ during fermentation was analyzed via northern transfer and the relative levels of CARl expression were determined. The trends in expression can be correlated to the nitrogen data and be used to partially explain differences in EC formation between the treatments. EC was quantified at the end of fermentation by GC/MS. In Montrachet yeast, a significant positive correlation was found between the timing of DAP addition, from early to late, and the final EC concentration m the wine (r = 0.9226). In one of the fermentations, EC levels of 30.5 ppb was foimd when DAP was added at the onset of fermentation. A twofold increase (69.5 ppb) was observed when DAP was added after 75% of the sugars were metabolized. When no DAP was added, the ethyl carbamate levels are comparable at a value of 38 ppb. In contrast, the timing of DAP additions do not affect the level EC produced by the yeast ECU 18 in this manner. The study of additional yeast strains shows that the effect of DAP addition to fermentations is strain dependent. Our results reveal the potential importance of the timing of DAP addition to grape must with respect to EC production, and the regulatory effect of DAP additions on the expression of genes in the pathway for arginine metabolism in certain wine yeast strains.

The seasons of Zarathustra and their correspondence to the metamorphoses of the spirit

Nietzsche employed metaphors frequently throughout his works. This is especially true in Thus Spoke Zarathustra. Although this is often aesthetically pleasing, it can be very difficult for the reader to understand the nuances and interconnections with the various metaphors. This is generally considered one of the main drawbacks of Thus Spoke Zarathustra. While it is beautifully written in a style that is incomparable today, much of what it is attempting to communicate is lost on the reader. This thesis explores the connection between the metamorphoses of the spirit and the seasons in Thus'Spoke Zarathustra, with the camel spirit corresponding to autumn, the lion spirit with winter, the child spirit with spring, and finally the Overman with summer. Although the Overman is not included among the three metamorphoses of the spirit, it will be argued that the Overman is a separate metamorphosis and must not be conflated with the child spirit despite their similarities. While Thus Spoke Zarathustra will be the primary text used, Nietzsche's other works will be employed to demonstrate that this connection between the metamorphoses of the spirit and the seasons runs through much of his thought. By demonstrating how the seasons are used in Thus Spoke Zarathustra, a deeper understanding of the work will be revealed. Further, this thesis will demonstrate that it is an intentional connection, and not merely coincidental or something that has been constructed and imposed upon the work. Bringing this correspondence between the metamorphoses of the spirit and the seasons to light will result in the need to rethink particular notions of Nietzsche's philosophy. The most apparent involves the Overman and the process of overcoming. Although the Overman has often been viewed as "the end" in the cycle of metamorphoses, it will be argued that this is not the case. The typical interpretation of the metamorphoses of the spirit regard it as a linear progression; however, it will be shown that the metamorphoses of the spirit is cyclical with the camel, lion, and child spirits endlessly repeating, much like the seasons.