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

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(Methods and Materials)
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=Methods and Materials=
 
=Methods and Materials=
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The test mashes were prepared by mixing 60 C (140F) water with a pulverized grist at a mash thickness of 4 l/kg:
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* mash A: 50% Weyermann Munich II, 50% Weyermann Pilsner, water residual alkalinity = 35 ppm CaCO<sub>3</sub>
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* mash B: 100% Weyermann Pilsner, water residual alkalinity = 115 ppm CaCO<sub>3</sub>
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The mash temperature was held stable at 60C (140F) for 10 min in a water bath and then the mashes were cooled to 25C (77F) within 5 min in an ice bath. Because of additional delays the samples stood at room temperature
  
 
=Results and Discussion=
 
=Results and Discussion=

Revision as of 21:52, 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

The test mashes were prepared by mixing 60 C (140F) water with a pulverized grist at a mash thickness of 4 l/kg:

  • mash A: 50% Weyermann Munich II, 50% Weyermann Pilsner, water residual alkalinity = 35 ppm CaCO3
  • mash B: 100% Weyermann Pilsner, water residual alkalinity = 115 ppm CaCO3

The mash temperature was held stable at 60C (140F) for 10 min in a water bath and then the mashes were cooled to 25C (77F) within 5 min in an ice bath. Because of additional delays the samples stood at room temperature

Results and Discussion

Conclusion

References

Acknowledgments