@masterthesis{TranNguyen, type = {Bachelor Thesis}, author = {Tran Nguyen, Anh Tho}, title = {The influence of zinc sulfate in the fermentation rate of cider under homebrewing conditions}, school = {Hochschule Rhein-Waal}, abstract = {OBJECTIVE: The purpose of this study was to first determine the effectiveness of zinc sulfate at concentrations of 0.5 and 1 PPM (Parts Per Million) on the fermentation rate of yeast when brewing cider under homebrewing conditions and to compare it to commercial yeast nutrient. Zinc is an essential mineral for the production of alcohol as it is a co-factor in alcohol dehydrogenase, the enzyme responsible for alcohol production in yeast. The general consensus of zinc levels needed for yeast fermentation is 0.4 - 1.07 PPM (Nicola and Walker, 2011). METHODS: Data was collected using a refractometer of the brews. There were five brews in total, one with yeast nutrient, two with zinc sulfate at 0.5 PPM and two at 1PPM along with their controls. RESULTS: A total of 25 brews, in five groups of five, were performed. The results showed that supplementing the yeast with commercial yeast nutrient significantly improved the fermentation rate, while zinc sulfate at 0.5 and 1PPM showed no significant difference when compared to the controls. CONCLUSIONS: While a certain level of zinc is needed for fermentation, this study did not find supplementing homebrew cider with zinc sulfate to significantly improve the fermentation rate in comparison with control brews. When compared to yeast nutrient, zinc sulfate was not found to improve the fermentation rate. In order to consider whether or not supplementing zinc can improve fermentation in homebrewing, more studies must be conducted with different factors taken into consideration such as the yeast variant, the juice used and the initial concentration of zinc compounds in the juice.}, language = {en} }