Sour Mash

Thursday May 16, 2024

So what exactly is the ‘Sour Mash’ process within whiskey production you may ask yourself and what exactly is its purpose and effects?

These are very good questions and ones that are more often that not deliberately shrouded in more than a little myth and marketing propaganda.

Dr James C Crow (1780 – 1854), is widely credited for perfecting and implementing the sour mash process with the bourbon distilling industry. Crow was a Scottish chemist who emigrated to America in 1820 and went to work for Oscar Pepper in Frankfort KY in 1838 as their head distiller. Crow was one of the first master distillers to apply a scientific approach to whiskey production, using implements such as a hydrometer, saccharometers, litmus paper and the likes, to improve and standardise mashing and fermentation processes and techniques.

To improve the performance of his bourbon fermentation, Crow used the sour mashing method to adjust the PH level or acidity of the ferment. Ensuring the correct acidic environment for the yeast, improves the performance and results in a better alcohol yield, with fewer ‘off’ flavours due to less yeast stress.

By the addition of spent spillage from the previously stripping run into the next fermentation, Crow found he could adjust the acidity, to provide a better environment for the yeast to work its magic.

It’s also reported that the sour mash method is the process of adding ‘live mash’ from an active fermentation into the next. This isn’t the original sour mashing technique, however, this process does inoculate the next fermentation from the previous, providing a degree of consistency between batches.

The water here in Cornwall is a lot softer than that of the Louisville, Kentucky area and therefore doesn’t take as much adjusting, however, by micromanaging the acidity of our fermentation, we can ensure a better, stronger, more complex fermentation with less ‘off’ flavours. This in turn rewards us with a superior ‘distillers beer’ to turn into our whiskey.

In today’s competitive whiskey marketing world, the term ‘Sour Mash’ is touted by many of the large bourbon producers, as some sort of magical secret flavour enhancing technique, when in fact its original intention was simply to enable a more consistent and efficient fermentation. It could be argued that the flavour advantages are minimal, but it can also be argued that a better more consistent fermentation produces a superior end product due to a stronger, less stressed fermentation.

At Penrock, we use Dr James Crow’s sour mash technique. We also inoculate new fermentation with ‘live mash’ from previous batches. Even though the water in Cornwall is markedly different to that of central Kentucky, we use every available method to ensure we produce the very finest whiskey possible.

Other articles about our Whiskey, Rum and Spirits

Our jounal about Whiskey, Rum and our process and how we do it the old fashioned Tennessee way

in the pursuit of the finest handcrafted, premium spirits

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