stable for a longer time. But even heat-processed molasses is subject to infections, which tend to settle on the surface of the liquids (osmotic pressure is too high for them to thrive within the molasses). Molasses stored for longer times is more likely to have surface contaminants, and the contamination only gets worse once water is added to prepare the wash, since water reduces the osmotic pressure to a point where the bacteria can begin rapid reproduction. Inoculation (heat pasteurization is the easiest approach for craft distillers) is then necessary to stop further formation of dextran, but then enzymes such as alpha amylase must be incorporated to break down the dextran into once-again fermentable sugars. Preparing the wash is easy enough if we know the starting brix of the molasses and target brix we want for the wash. As a rule of thumb, the brix for the wash should be at 25 or below, otherwise the osmotic pressure will prevent the yeast from surviving and thriving. But quantifying how much water to use is a bit tricky at first. For example, if we wanted to dilute 1 gallon of 50 brix molasses by adding water, and the target brix is 25, the initial thought would be to add 1 gallon of water to the molasses, but this would be wrong: Brix is a measure of solids in a liquid, thus we would have to weigh the gallon of 50 brix molasses and then add exactly that much weight of water to it (which would be more than a gallon). Fermenting the molasses wash is a topic for a different article, so for now letâ€™s jump to the end of the fermentation. How do we know fermentation has completed and, more importantly, do we have
dextran or other un-fermentable sugars leftover? Large companies or those with access to specialized labs can simply run a sample of the wash through a HPLC (high-performance liquid chromatography) and determine final sugars fairly quickly. Craft distillers rarely have this luxury, but they do have a quick and straightforward way to test the wash: Taste it! If CO2 release has finished and there are no visual signs of fermentation activity, before transferring the wash to the still I always take a small sample and drink it. The smell should be sweet, like the molasses we started with, but the flavor must be sour and acidic, nothing sweet in it. If there is real sweetness in the taste, then either the yeast was killed prior to finishing the fermentation of all the sugars, or the remaining sugars are nonfermentable. Hopefully by now you will have a larger degree of appreciation for molasses, from High Test to the lowest grade available. Understanding its high sugar content and pasteurization explain why molasses is a preferred material for rum producers, versus fresh cane juice that can only be obtained during the harvest and which requires more energy to ferment and distill. So, is molasses really a by-product of the sugar industry? The answer: absolutely not!
Luis Ayala is an international rum consultant and broker of specialty aged rums. He is founder of The Rum University, Rum Central and Got Rum? magazine. Visit www.gotrum.com or email firstname.lastname@example.org for more information.
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