labeling) equipped with a Gas Chromatographer (GC) and ask
terms, light rums will have less than 50 mg of total congeners
them to run tests on the following:
per 100 ml AA. Heavy rums will have more than 250 mg of total congeners per 100 ml of AA, and medium rums will be
• Acetaldehyde
(heads)
• Ethyl Acetate
(heads)
will have little heads and tails, while the opposite will be true
• Methanol
(heads)
for dirty or “wide” cuts.
• Ethanol
(heart)
somewhere in between these two ranges. Very clean “hearts”
Armed with this knowledge you can evaluate if you are fermenting and distilling efficiently. There is nothing worse for
• Amyl
(tails)
• Butanol
(tails)
yeast only to have to discard the resulting alcohol as part of
• Propanol
(tails)
unwanted cuts. Some of the potential problems that result in
When you receive the results, they should look like the graph in Figure 01 (the numbers will, of course, be different). And somewhere near the graph, either above it, below it or on a separate page, you should see a table something like Figure 02. The graph with the peaks is very eye-catchy; the prominent peak above the number “6” on the graph is the ethanol, which is not quantified when you run a congener report like the one above. However, all the usable data is on the table.
HOW TO READ THE GC RESULTS TABLE: You will want to focus on the “Amount mg/100 ml” column, but make sure you understand first if the “100 ml” refers to 100 ml of the original concentration or, as in most cases, it refers to 100 ml of the alcohol at 100% ABV (200-Proof). To find this out, look for the word “Multiplier” on the report. If Multiplier is “1.0000”, then the report is showing mg of congeners per 100 ml of the alcohol at the
a distiller than spending time and money on raw materials and
wasted alcohol or distilling time include:
• Improper pitch rate (too little yeast or unhealthy yeast) • Improper wash dilution (osmotic pressure may be too high) • Improper nutrition for yeast • Uncontrolled fermentation temperature • Unnecessarily long fermentation times • Wrong yeast for the type of rum being produced • Wrong type of still for the type of rum being produced Two common problems related to abundant heads and tails are described below. Solving them usually requires troubleshooting at different levels in order to isolate the root cause(s), but here are a few starting points...
fig. 02
original strength. If, on the other hand, it reads “2.5000” and the original alcohol was at 40% ABV (80-Proof), then the report is showing mg of congeners per 100 ml of AA (Anhydrous Alcohol). There is no standard across all
rum-producing
countries
or companies, but in general
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