Tips & Tidbits - The pH Scale
The pH scale is used to determine the concentration of hydrogen ions, which indicate the level of acidity or alkalinity of a given compound. The pH scale's range starts at zero and ends at fourteen. Water has a pH of 7 and is considered neutral. Anything with a pH below seven is acidic, and anything with a pH above 7 is considered alkaline. So, a low pH means a high acidity and a high pH means a low acidity.
pH for Vintnors
In the wine world, pH is critical. TA(total acidity) refers to the amount of acid in the grapes, juice, or wine whereas pH refers the strength of the acidity. Checking pH gives a numerical indication of the ripeness of the grape. As grapes ripen the pH will rise as the TA drops. White grapes are generally ready to pick when the pH is 3.1 -3.2 where red grapes are on the higher side 3.3 - 3.6. A moderately acidic solution is the proper environment for yeast metabolism, but the range is fairly narrow. High pH wines, 3.8 or greater, will be soft and flat and have a problem with oxidation, microbiological stability and the color will seem washed out. Wines with a low pH, 2.8, will be very sour.
pH for Brewers
For all grain brewers, pH is extremely important because the enzymes that convert starches into fermentable sugars are quite fussy about the pH at which they will work. The optimum pH for diastatic enzymes is 5.2 - 5.8. Proteolytic enzymes prefer 4.2 - 5.3. Usually a compromise is made at 5.2. For extract brewers pH is less important because the folks who made the extract have already dealt with it for you.
pH for Green Bay Packers fans or Cheese makers
Milk has a pH of 6.6. Cheddar cheeses have a final pH of 5.3, whereas fresh cheeses like cottage cheese have a pH of 4.5