For many years I never worried about balancing pH or even what my water profile was when brewing. After all, the beer was fine and most of the time I was brewing with extract, so pH did not matter much.
However once I started all grain brewing, the water I brewed with suddenly started to matter. It also helped that I moved to an area with extremely hard water, which forced me to use bottled water to produce anything reasonably resembling beer. It turns out that the pH of your mash has a huge impact on the mashing process as well as taste of your finished all-grain beer.
Understanding pH: Alkalinity and AcidityPure water has a pH of 7.0, which means that it is neither acidic nor alkaline. If you are into chemistry, this means that the free H+ (hydronium) ions are balanced with the OH- (hydroxide) ions giving equal concentrations capable of forming H2O. If water has an excess of H+ ions, we call it acidic (lower pH), while an excess of OH- ions gives us alkaline (higher pH) water.
Now it we take our pure water in the form of rain and run it down through the atmosphere and soil it picks up CO2 and Calcium from the soil, these elements will bind with the H+ ions leaving a bunch of free OH- (hydroxide) ions making our water more alkaline. This increases the pH of the water. Most tap water is slightly alkaline for this reason. Really hard water can be highly alkaline.
Interestingly all malts (and dark malts in particular) have phosphates in them that react with the calcium and magnesium ions in alkaline water freeing up H+ ions that make the mixture acidic. Adding malt, especially dark malt, lowers the pH of the malt water mixture in the mash.
The Importance of Mash pHThe pH of the mash is very important for proper conversion of sugars during the mash and also due to its effect on finished beer. Mashing should always take place at a pH between 5.1 and 5.3. However, its important to note that we are talking about the pH of the mixed mash, which as I point out above depends on the color and quantity of malts added to the beer. In most cases the mixed mash will be slightly alkaline (pH above 5.3) and require an acidic addition or buffer to bring it down to 5.2.
Though some commercial brewers can accurately predict the pH of their mash in advance, few homebrewers have the detailed knowledge and data available to do this. The problem is that the color, quantity and even type and supplier of the malt can change the pH. In addition, your starting water and its interactions with the malts may vary with each recipe. Remember that commercial brewers brew the same recipe every time using the same ingredients, while homebrewers do this only rarely.
That's why homebrewers are reduced to measuring the pH of each mash right after it is mixed and then adjusting our pH as early as possible in the mashing process.
Measuring pH can be done in several ways including pH (litmus) strips, precison pH strips and even using an electronic pH meter. Of the three methods, precision pH strips are usually most cost effective and practical. Standard pH strips lack the precision needed to measure down to a tenth of a point pH, and electronic meters are expensive and require frequent replacement of the electrodes to maintain accuracy.
Another practical consideration is that the mash is usually hot, so you need to adjust the pH reading for temperature. Hot wort will almost always provide a higher pH reading than the actual wort. You can compensate for this either by rapidly cooling the sample to room temperature before measuring or applying a correction factor after taking the reading. Check the documentation with your pH strips to determine the appropriate correction.
Methods for Adjusting Mash pHThere are several methods available to the homebrewer for adjusting the pH of your wort. As noted earlier, in most cases you will need to lower your pH to reach the 5.2 target level.
· Calcium and Magnesium Salts: Three salt: Gypsum (CaSO4), Epsom Salt (MgSO4) and Calcium Chloride (CaCl) can be added to lower your pH. The calcium and magnesium ions in these additions reduce the alkalinity of the water. Note, however, that the sulfate and chloride ions react with the phosphates from the mash, which can lead to undesirable flavors. As a result you need to limit the amount added. You can calculate appropriate amounts using a water tool such as the one in BeerSmith. Suggested limits are 50-150 ppm for calcium, 50-150 ppm for sulfate, 0-150 ppm for chloride and 10-30 ppm for magnesium. See our article on water profiles for more information.
· Food Grade Acids - Acid additions counter the H+ ion and directly lower the alkalinity of the mash. Popular additions include phosphoric acid, sulfuric acid and lactic acid. All of these contribute other flavors and ions to the beer as well, which can again cause problems if used in excessive amounts. Phosphoric acid is used to make soda, and will contribute phosphates to the mash. Lactic acid will add lactates, and is used in many Belgian styles to sour the beer. Sulfuric acid will contribute sulfates. In general you should add the minimum needed to achieve your target pH. The amount will vary depending on the concentration of your acid and wort volume.
· Acid Malt - Because of German purity laws (the Reinheitsgebot) that prevent additives to German beer, sour malt (called acid malt) is used to aid in the brewing of light beers to lower mash pH. Acid malt is made by souring malt with lactic bacteria for a short period which effectively creates lactic acid. Adding acid malt is effectively equivalent to adding lactic acid to the mash. Adding one percent of acid malt effectively lowers the pH of the malt by approximately 0.1 pH.
· Sour Mash - Another technique developed by the Germans is to create a sour mash which again contains lactic acid produced by lactic bacteria. The technique is to mash a quantity of grain, cools it to about 80F and then adds some fresh malt (which contains lots of lactic bacteria naturally) and lets the mixture sit overnight. The bacteria will quickly sour the mash and start fermenting it, again creating lactic acid. The next day this sour mash can be mixed with a regular mash to lower its pH. The challenge with sour mashing is that it can be somewhat inconsistent in pH and also labor intensive.
· Acid Rest - Though seldom used today thanks to modern highly modified malts, an acid rest in the 95F (35C) range can break down phytins in the malt into phytic acid that will lower the mash pH. This was traditionally done in German triple decoction mashes, and is most effective when used with undermodified malts.
· 5.2 Stabilizer - A number of brew stores now carry an additive called 5.2 stabilizer. This is a powder you can add to the beer to lower the mash pH to 5.2. It consists of buffers that reduce the alkalinity of the mash to reach a 5.2 level. As long as your starting water is not completely out of kilter, this is a good simple solution for many homebrewers.
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啤酒釀造糖化用水處理很多年來，我從來沒有擔心過pH值的問題，甚至當我釀酒的時候我都不知道我的水質是什麼樣的， 畢竟，我釀的啤酒還不錯，而且大部分時間我都在用萃取物釀造，所以pH值並不重要。
然而，一旦我開始釀造用全穀物釀造，我的釀造水突然開始變得重要。我搬到了一個水很硬的地方，這也讓我不得不用瓶裝水來生產任何類似的啤酒。事實證明，糖化的pH值對糖化過程和成品啤酒的口感有很大的影響，特別是全穀物啤酒。
了解pH：鹼性和酸性純淨水的pH值為7.0，也就是說它既不是酸性的，也不是鹼性的。如果你對化學感興趣，這意味著自由H+（氫離子）與OH-（氫氧化物）離子平衡，使能形成H2O的濃度相等。如果水有過多的H+離子，我們稱之為酸性水（低pH值），而過量的OH-離子使我們得到鹼性水（高pH值的水）。現在我們以雨水的形式將純淨的水輸送到大氣中，在土壤中吸收二氧化碳和鈣，這些元素會與氫離子結合，留下一些游離的氫氧根離子，使水變得顯鹼性，這會增加水的pH值。大部分自來水是微鹼性的，就是這個原因。真正的硬水可以是高鹼性的。
有趣的是，所有的麥芽（尤其是黑麥芽）中都含有磷酸鹽，它們與鹼性水中的鈣和鎂離子反應，釋放出使混合物呈酸性的氫離子。添加麥芽，特別是黑麥芽，會降低麥芽汁中麥芽水混合物的pH值。
糖化pH值的重要性
糖化過程中糖的定量轉化是非常重要的，也是由於它對成品啤酒有很大的影響。糖化應始終在pH值在5.1-5.3之間進行。然而，需要注意的是，我們討論的是混合麥芽漿的pH值，正如我上面所指出的，它取決於麥芽的顏色和加入啤酒的麥芽數量。在大多數情況下，混合後的麥芽漿呈微鹼性（pH值在5.3以上）並需要酸性添加劑或緩衝劑使其降至5.2。儘管一些商業釀酒商可以準確地預測他們的麥芽漿的pH值，但很少有家庭釀酒商有詳細的知識和數據可以做到這一點。問題是麥芽的顏色、數量甚至種類和供應商都可以改變麥芽的pH值。此外，你的起始水和它與麥芽的相互作用可能會因每個配方而有所不同。記住商業釀酒商每次用同樣的原料釀造同樣的配方，而自釀啤酒的人很少這樣做。
這就是為什麼自製者在混合後會降低到測量每個糖化過程中的pH值，然後在糖化過程中儘早調整我們的pH值。
測量pH值可以通過多種方式完成，其中包括石蕊試紙、預檢測pH試紙，甚至使用電子pH計。在這三種方法中，精密pH試紙通常是最具成本效益和實用性的。標準pH試紙不能精確測量pH值到十分之一點，電子測量儀價格昂貴，需要頻繁更換電極以保持準確性。另一個實際的考慮因素是，糖化通常是熱的，所以你需要調整溫度的pH值。熱麥汁幾乎總是提供比實際麥汁更高的pH值。你可以通過在測量前迅速將樣品冷卻到室溫來彌補這一點，或者在測量後使用校正因子。用pH試紙檢查文檔，以確定適當的校正。
調整糖化度的方法
有幾種方法可供家庭釀造者調整你的麥芽汁的pH值。如前所述，在大多數情況下，你需要降低你的pH值，以達到5.2的目標水平。
鈣和鎂鹽：三種鹽：石膏（硫酸鈣），瀉鹽（硫酸鎂）和氯化鈣（氯化鈣）的添加可以降低您的pH值。這些添加劑中的鈣和鎂離子降低了水的鹼度。但是請注意，硫酸鹽和氯離子會與糖化後產生的磷酸鹽發生反應，從而產生不想要的味道。因此，你需要限制添加量。您可以使用Beersmith中的水計算工具來計算適當的量。啤酒史密斯。鈣的建議限量為百萬分之五十至一百五十，硫酸鹽的限量為五十至一百五十，氯化物的限量則為零到一百五，鎂離子的限量則為十到三十。你可以在我有關於水質的文章中看到更多信息。
食品級酸—酸的添加對抗H+離子和直接降低糖化的鹼度。常用的添加劑包括磷酸、硫酸和乳酸。所有這些都會對啤酒的風味和離子有貢獻，但是，這可能也會再次引起問題，如果使用過量。磷酸通常被用於制蘇打，並且在啤酒糖化時貢獻磷酸。乳酸會增加乳酸鹽，在許多比利時啤酒中使用乳酸。硫酸會生成硫酸鹽。一般來說，你應該添加最低需要達到你的目標pH值。量將根據你的酸濃度和麥芽汁體積度而變化。
· 酸麥芽-由於德國純淨法（Reinheitsgebot）禁止添加添加到德國啤酒中，酸麥芽（稱為酸麥芽）被用來幫助釀造低度啤酒，以降低糖化液的pH值。酸麥芽是在短時間內用乳酸菌使麥芽變酸，有效地產生乳酸。添加酸麥芽的效果相當於在麥芽漿中添加乳酸。添加1%的酸性麥芽，有效地降低麥芽的pH值約為0.1 pH。
· 酸麥芽汁-德國人發明的另一種技術是製造一種酸麥芽漿，其中含有乳酸菌產生的乳酸。該技術是將大量穀物搗碎，冷卻至80華氏度左右（26.7℃），然後加入一些新鮮麥芽（自然含有大量的乳酸菌），讓混合物靜置一夜。這種細菌會很快地使糖化物變酸並開始發酵，再次產生乳酸。第二天，可以將這種酸麥芽汁與普通麥芽汁混合以降低其pH值。酸糖化法的挑戰在於，它的pH值和預想的有些不一致，而且勞動強度大。
· 酸休止-雖然在今天很少有人使用，由於現代高度改良麥芽，酸休止在95F（35C）範圍內可以將麥芽中的肌醇六磷酸分解成植酸，從而降低麥芽中的pH值。這在傳統的德國三重麥芽泥中進行，並且在與改良的麥芽一起使用時最為有效。
· 5.2穩定劑 許多釀酒廠現在都有一種叫做5.2穩定劑的添加劑。這是一種粉末，你可以添加到啤酒中，以降低糖化pH至5.2。它包括緩衝液，降低鹼度的糖化達到5.2水平。對於家釀愛好者來說，只要你的開始的水沒有完全失去平衡，這是一個很好的簡單的解決方案。在本地找不到這些物品？
可以從MoreBeer獲得一整套水穩定劑，並且同時BeerSmith網站會為其提供技術支持。
再次感謝您一直以來的支持！
以上翻譯來自於Beersmith的文章，由於翻譯者的英語水平實在有限，所以大家看到有錯誤的地方歡迎指出！！