Historically fermentation vessels for Bourbon whiskey were made, of woods, such as cypress, redwood and larch, but stainless steel is now preferred. It is recognized that the use of stainless steel results in a slightly different taste, but this has no effect on consumer pre ference. Where a 72 h fermentation is used, it is usual to control the temperature at a maximum of 32-35°C. This ensures a high quality product by maintaining yeast activity throughout the fermentation period.