Lowering PH

Lowered my starting PH on my all molasses washes from 5.5 to 5 and have an increase in wash ABV by 0.6%. Is this a normal thing to occur or maybe just for the molasses and yeast I'm using which is 493EDV?


  • Yeast generally prefer lower pH, and of course they acidify the wash by creating organic acids. So your fermentation may have come a little closer to finishing all the fermentables. IOW a faster more complete fermentation. The only way I can think of to tell is to assay the sugars in the wash (a fehling test); or do a brewers forced-fermentation-test on the start mix to see where the endpoint is. Some commercial beer brewers were staring as low as 4.5!

  • Yep.

    Lowering the starting pH will reduce the ability for opportunistic bacteria to outcompete yeast and convert sugar or alcohol to organic acids.

    Lowering the starting pH is usually the best way to correct pH crashes in cane-based washes - though entirely counterintuitive.

  • edited February 29

    For example: Consequences of a Lower pH @ Ethanol Produzer Magazine

    At an ethanol plant experiencing bacterial contamination, lowering the pH in the propagator/fermenter is typically the first step used to control bacterial growth. Phibro’s Diagnostic Kit services show that over 80 percent of the bacterial contamination in ethanol plants is from the lactic acid bacteria (LAB) family. The pH for optimal growth of most LAB is between 5.5 and 5.8. In contrast, S. cerevisiae yeast can tolerate and multiply better than most bacteria in acidic environments—from pH 4.0 to 6.5.

    Knowing this, it seems logical to lower the pH during contamination to inhibit the bacteria while allowing the yeast to grow.

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