Difference between revisions of "An Evaluation of the suitability of colorpHast strips for pH measurements in home brewing"

From German brewing and more
Jump to: navigation, search
 
Line 1: Line 1:
EMD's colorpHast strips for the pH range 4.0 to 7.0 are very popular among home brewers.  
+
EMD's colorpHast strips for the pH range 4.0 to 7.0 are very popular among home brewers. Their more narrow range and improved readability are an improvement over economy pH strips. While they don't provide the precision of a pH meter they don't require the maintenance necessary for the latter and are therefore a very attractive means of testing pH in home brewing.
 +
 
 +
But earlier studies done by myself have shown that these strips seem to have a systematic error of -0.3 pH. I.e. the strips tend to report a pH reading that is about 0.3 pH less than what is determined with a calibrated pH meter:
 +
* [[colorpHast_vs_pH_meter|colorpHastStrips vs. a pH meter]]
 +
* [[Effects_of_mash_parameters_on_fermentability_and_efficiency_in_single_infusion_mashing#pH_meter_vs._colorpHast_strips| micro mashing experiments]]
 +
 
 +
Since this error could be the result of lot specific variations I needed a larger sample. To get this larger sample I solicited the help from fellow brewers on the [http://forum.northernbrewer.com/ Northern Brewer] and [http://www.homebrewtalk.com/ HomeBrewTalk.com] forms. They sent me a few of their colorpHast strips and I made test mashes and
 +
tested these mashes and a sample of beer with these test strips and a pH meter.
 +
 
 +
In the end it was confirmed that the colorpHast strips have a -0.3 systematic error when they are used for testing the mash pH. No significant error was found for testing beer pH but the range of confidence with which the strip's color could be interpreted was larger than for the mash pH experiments.
  
 
=Methods and Materials=
 
=Methods and Materials=

Revision as of 04:16, 2 August 2009

EMD's colorpHast strips for the pH range 4.0 to 7.0 are very popular among home brewers. Their more narrow range and improved readability are an improvement over economy pH strips. While they don't provide the precision of a pH meter they don't require the maintenance necessary for the latter and are therefore a very attractive means of testing pH in home brewing.

But earlier studies done by myself have shown that these strips seem to have a systematic error of -0.3 pH. I.e. the strips tend to report a pH reading that is about 0.3 pH less than what is determined with a calibrated pH meter:

Since this error could be the result of lot specific variations I needed a larger sample. To get this larger sample I solicited the help from fellow brewers on the Northern Brewer and HomeBrewTalk.com forms. They sent me a few of their colorpHast strips and I made test mashes and tested these mashes and a sample of beer with these test strips and a pH meter.

In the end it was confirmed that the colorpHast strips have a -0.3 systematic error when they are used for testing the mash pH. No significant error was found for testing beer pH but the range of confidence with which the strip's color could be interpreted was larger than for the mash pH experiments.

Methods and Materials

Results and Discussion

Conclusion

References