Equipment Glossary Acknowledgements

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Section 1
Brewing Your First Beer With Malt Extract
Section 2
Brewing Your First Extract and Specialty Grain Beer
Section 3
Brewing Your First All-Grain Beer
14 How the Mash Works
15 Understanding the Mash pH
16 The Methods of Mashing
17 Getting the Wort Out (Lautering)
18 Your First All-Grain Batch
Section 4
Formulating Recipes and Solutions


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Chapter 14 - How the Mash Works

14.2 The Acid Rest and Modification

Before the turn of the (last) century, when the interaction of malt and water chemistry was not well understood, brewers in Pilsen used the temperature range of 86-126F to help the enzyme phytase acidify their mash when using only pale malts. The water in the area is so pure and devoid of minerals that the mash would not reach the proper pH range without this Acid Rest. Most other brewing areas of the world did not have this problem.

Pale lager malt is rich in phytin, an organic phosphate containing calcium and magnesium. Phytase breaks down phytin into insoluble calcium and magnesium phosphates and phytic acid. The process lowers the pH by removing the ion buffers and producing this weak acid. The acid rest is not used nowadays because it can take several hours for this enzyme to lower the mash pH to the desired 5.0 - 5.5 range. Today, through knowledge of water chemistry and appropriate mineral additions, proper mash pH ranges can be achieved from the outset without needing an acid rest.

Previous Page Next Page
How the Mash Works
An Allegory"
Mashing Defined
The Acid Rest and Modification
The Protein Rest and Modification
The Starch Conversion/Saccharification Rest
Manipulating the Starch Conversion Rest
Real Beer Page

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Appendix A - Using Hydrometers
Appendix B - Brewing Metallurgy
Appendix C - Chillers
Appendix D - Building a Mash/Lauter Tun
Appendix E - Metric Conversions
Appendix F - Recommended Reading

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All material copyright 1999, John Palmer