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Author: Subject: A dilemma with molasses and pH control

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Registered: 18-9-2018
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[*] posted on 26-5-2020 at 20:35
A dilemma with molasses and pH control

I've been working as a fermentologist for a couple years now exploring yeast fermentation of molasses. The absolute best aroma and resulting flavor occurs when the pH of the molasses wash is close to 6 throughout the ferment with a particular kind of yeast. Raw molasses often has a resting pH between 4.7-5.3, which needs to be brought up to the optimal pH range.

The biggest problem facing this process is the creation of off-odors when raising the pH with an excess of strong base, such as calcium hydroxide. Calcium hydroxide is used to both raise the pH and help precipitate some of the ash and gunk that remains in suspension in molasses (which is then removed with a centrifuge - thinning this out helps the yeast to ferment all the sugars. Use of other salts, such as sodium or potassium, further contributes to the osmotic pressure which will stress the yeast). I can usually only bring the pH up by 0.5 before off-odors start to develop, which I believe occurs from reaction of the strong base with nitrogenous compounds in the molasses. For low pH molasses, this makes it hard to reach the optimal fermentation pH.

Some treatment with strong base is desirable, as it cleaves the glycosides that lock away the aroma precursors. However, it can only go so far and then I have to find some other way to reach high pH without ruining the molasses, antagonizing the yeast, or creating off-aromas.

Addition of ammonium hydroxide has been attempted thoroughly, though this has problems, namely with over accumulation and the potential creation of high amounts of ethyl carbamate (the yeast will eat it when growing, though if an excess remains it can ruin aroma in the distillate and/or contribute to an accumulation of ethyl carbamate through reaction with carbon dioxide and ethanol).

Does the biochem community have any creative ideas for increasing the pH without increasing the osmotic pressure or adding an excess of strong base? I would be deeply indebted to anyone with good advice.

Thank you,
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