ETHANOL PRODUCER'S DATA BASE

The "p" in pH is always written as lower case, not upper case.
The "p" stands for potential. The "H" stands for Hydrogen.
pH of a fermentation will go more acidic as the ferment progresses due to yeast metabolism byproducts being excreted into the fermenting solution.
For this reason, we in the beverage brewing/distilling world start our fermentations at the range of
- pH 5 - pH 5.5 so that when finished, the pH will still be around pH 4 which ensures we don't stop or retard the yeast action too soon ( i.e. before all the sugars are converted to ethanol & CO2 ).
pH scale is an inverse logarithmic representation of Hydrogen-Ion ( H+ ) concentration in a solution.
- Each individual pH unit is a factor of 10 different than the next higher or lower unit.
- This means that pH 6.0 is 10 times ( 10 x 1 ) more acidic than pH 7.0,
- and pH 5.0 is 100 times ( 10 x 10 ) more acidic than pH 7.0.
Given all of the above, it is clear that the correct pH conditions (slightly acid) of fermentations at start will retard bacterial growth, allowing a correct yeast growth & metabolism environment and ensure virtually trouble-free progress to completion.
- Slainte! regards Harry SOURCE: ( Posting No: 8031 at: The Alcohol Fuel Forum )
  - Thank you Harry

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The pH is a measure of the acidity or alkalinity of an aqueous solution expressed on a scale of 1-14.
- Neutral is pH 7, pH 1-7 is acid, and pH 7-14 is alkaline.

The pH is measured with an electronic pH meter or test papers that change color according to the pH of the solution being tested.
- These meters and papers are available from swimming pool supply houses, garden shops, and laboratory supply companies.

Control of pH during the mashing and fermentation process is important for two reasons:
The growth of harmful bacteria is retarded by acid solutions.
- Yeast will grow only in a mildly acid solution.

Most grain mashes have a naturally acid pH of between 5.4 and 5.6 after conversion has been accomplished.
Other materials, notably saccharine substances like molasses and fruit pressings, have a naturally alkaline pH and must be acidified prior to fermentation.

The principal bacterial contaminants in a distillery are those that form lactic acid.
Although the production of fuel alcohol is not concerned with the taste of the product,
- Lactic acid formed subtracts from the yield of alcohol.
The production of lactic acid and other contaminants should therefore be avoided as much as possible.
Below about 4.1 to 4.4 is detrimental to other processes taking place during fermentation.
The development of these micro-organisms is severely repressed at pH values under 5.0.
Above 5.0 their growth is rapid.
The optimum pH range then is 4.8 to 5.0.
Consequently, the pH should be checked during the cooking and conversion.
LOWERING pH: If it is above 5.0, it should be reduced by the addition of acid.
The acid most commonly used is sulfuric, although any mineral acid is perfectly suitable.
Hydrochloric (muriatic) acid, for example, is available from swimming pool suppliers.
The acid should be added cautiously, the mash stirred, and the pH checked.
RAISING pH: To raise the pH, use with sodium hydroxide caustic soda or ordinary lime.
CAUTION: Do not over correct, or you may have to scrap the mash.

Adjusting pH

The pH scale ate left shows the relative acidity of a solution.

It also shows the additives in order to adjust the pH to the desired precise Fermentation levels.

To Lower pH: Add more acid materials such as sulphuric or muriatic acid.

To Raise pH: Add more basic materials such as Lye, Amonia, Baking Soda.

The optimum pH for yeast activity is 4-6.
The fact is, that the pH of the cell interior of the yeast remains quite constant at about
pH 5.8, regardless of any relatively wide pH variations in the fermenting medium.
The enzymes involved in fermentation thus operate in an optimum pH environment within the yeast cell that is largely unaffected by external changes in pH.

Simplicity in Applied technology