Ask the Ex­perts

Craft Beer & Brewing Magazine - - Contents -

Homebrew ex­pert Brad Smith, au­thor of the Beer­smith home­brew­ing soft­ware and the voice behind the Beer­smith pod­cast, tack­les ques­tions about ph me­ters, elim­i­nat­ing bac­te­ria, and over car­bon­at­ing a batch.

I pur­chased an in­ex­pen­sive ph me­ter to man­age my mash ph, but I’m having a hard time get­ting con­sis­tent read­ings from it? Man­ag­ing your mash ph within the 5.2–5.6 range is im­por­tant for all-grain brew­ers. While you can es­ti­mate mash ph and make ba­sic ad­just­ments us­ing soft­ware, it is still im­por­tant to have a good-qual­ity ph me­ter to ver­ify your ph.

You men­tion that you pur­chased an in­ex­pen­sive ph me­ter, and this could cer­tainly be the source of your prob­lems. Many low-cost me­ters are not ter­ri­bly ac­cu­rate, having vari­abil­ity of +/– 0.1 ph or higher. Very cheap ones may not be suit­able for beer brew­ing.

Some of the fea­tures you should look for in a ph me­ter in­clude an ac­cu­racy of +/– 0.01 ph, au­to­matic tem­per­a­ture com­pen­sa­tion, a good (dig­i­tal or ana­log) cal­i­bra­tion sys­tem, and—ide­ally—re­mov­able probes. Re­mov­able probes let you re­place the ph elec­trodes, as these will wear out and be­come non-lin­ear within two to three years for a typ­i­cal unit.

A se­cond source of your prob­lems could be im­proper cal­i­bra­tion of the unit. Any ph me­ter must be cal­i­brated be­fore use. To do this, you need to pur­chase a “ph Buf­fer Cal­i­bra­tion Kit.” The kit con­tains three dif­fer­ent so­lu­tions with a known ph of 4.0, 7.0, and 10.0. In ad­di­tion, I rec­om­mend pur­chas­ing elec­trode stor­age so­lu­tion, which is a so­lu­tion you want to store your probes in to ex­tend their life and main­tain cal­i­bra­tion.

For a dig­i­tal ph me­ter, you sim­ply push the cal­i­bra­tion but­ton and then put the probes into each of the fixed so­lu­tions when prompted, and the unit will mea­sure each and cal­i­brate the unit. Cal­i­brat­ing an ana­log unit is sim­i­lar, but typ­i­cally you ad­just a dif­fer­ent cal­i­bra­tion knob for each of the known so­lu­tions.

What I rec­om­mend is to cal­i­brate your unit us­ing the known so­lu­tions and then wait a few hours and mea­sure the known so­lu­tions again. You should get good read­ings from the unit as it should be able to main­tain cal­i­bra­tion for at least a few days if you prop­erly store your probes in the stor­age so­lu­tion. If you don’t get good read­ings from the cal­i­bra­tion buf­fers, I would con­sider re­plac­ing the me­ter with a good-qual­ity ph me­ter with the fea­tures men­tioned above. Your sour-beer prob­lem is al­most cer­tainly be­ing caused by bac­te­ria. Bac­te­ria such as Lac­to­bacil­lus and Pe­dio­coc­cus oc­cur nat­u­rally and will in­fect and rapidly sour a batch of beer if you don’t kill them off us­ing san­i­tiz­ers. These bac­te­ria pro­duce lac­tic acid and are widely used in sour-beer brew­ing.

Poor san­i­ta­tion could be the cause, but if you have not changed your san­i­ta­tion process in the past year, it may not be the prob­lem. The fact that the prob­lem is oc­cur­ring from batch to batch and you did not have it ear­lier in­di­cates that some of your equip­ment may be in­fected. Most likely one or more pieces of equip­ment on the “cold side” of your sys­tem are in­fected with bac­te­ria, which is then sour­ing your beer dur­ing trans­fer, fer­men­ta­tion, or stor­age.

I say that the “cold side” is the prob­lem be­cause your beer is not sub­ject to in­fec­tion dur­ing the mash, and the boil as the act of boil­ing will kill any bac­te­ria. How­ever, it is pos­si­ble for your chiller, pump, trans­fer tubes, fer­men­tor, or even bot­tling bucket or kegs to be in­fected.

The most likely lo­ca­tion for an in­fec­tion is plas­tic, rub­ber, or sil­i­cone. Un­for­tu­nately, even a small scratch in a plas­tic bucket can har­bor bac­te­ria that are very dif­fi­cult to re­move. While stain­less-steel and other me­tals are largely im­per­vi­ous to in­fec­tion if prop­erly san­i­tized, it is pos­si­ble for your fit­tings, gas­kets, valves, pump heads, and tubes to har­bor bac­te­ria.

At a min­i­mum, I rec­om­mend dis­as­sem­bling all of your fit­tings, hoses, gas­kets, valves, pump heads, and other in­ter­faces

Last year I was mak­ing some great beer, but sev­eral batches ago I started get­ting sour fla­vors in my beer, and it seems to be get­ting worse with ev­ery batch. What can I do?

and giv­ing them a thor­ough clean­ing and then soak­ing for a bit in san­i­tizer. If that fails, you might want to con­sider re­plac­ing old hoses, gas­kets, plas­tic uten­sils, and other rub­ber and plas­tic in your sys­tem to elim­i­nate po­ten­tial sources of an in­fec­tion.

Fi­nally, I want to men­tion that it is also pos­si­ble to cre­ate sour beer if you have im­prop­erly stored in­gre­di­ents, such as wet malts. In this case, an in­fec­tion of the malt be­fore brew­ing can pro­duce lac­tic acid in the malt or mash that then can carry for­ward to the beer. Es­sen­tially, you are cre­at­ing a sour mash. This is far less com­mon than a cold-side bac­te­rial in­fec­tion, but it is a pos­si­bil­ity you should be aware of.

I’ve re­cently started brew­ing with ex­tract and my beers have been con­sis­tently over­car­bon­ated. What could be the cause?

There are sev­eral pos­si­bil­i­ties, in­clud­ing too much car­bon­at­ing sugar, bot­tling too soon, and us­ing poor-qual­ity malt or yeast. Let’s walk through each of these one at a time.

First, it is pos­si­ble you are us­ing too much sugar to car­bon­ate the beer. For ex­am­ple, a lot of beer kits come with a generic amount of corn sugar (or other sugar) to be used for carbonation. It’s not un­com­mon to see a pack­age of 5 oz (142 g) or more of corn sugar. How­ever, to achieve an av­er­age level of carbonation on a 5 gal (19 l) batch, you re­ally only need about 4.2 oz (119 g) of corn sugar.

You can also run into sim­i­lar prob­lems if you try to mea­sure carbonation sug­ars by vol­ume. Old books of­ten had things such as “2/3 cup of corn sugar” to car­bon­ate. Not sur­pris­ingly, corn-sugar den­sity varies de­pend­ing on source, so 2/3 of a cup could be too much or too lit­tle.

To avoid both of these is­sues, I rec­om­mend you cal­cu­late the proper weight of sugar needed us­ing soft­ware or an on­line cal­cu­la­tor and then weigh the corn sugar (or other sugar) to get an ex­act amount.

An­other pos­si­bil­ity is that you sim­ply bot­tled your beer too soon. When you do this, the beer will con­tinue to fer­ment in the bot­tle, over car­bon­at­ing your beer. Many new brew­ers are quick to bot­tle their beer so they can en­joy it. More ex­pe­ri­enced brew­ers are a lit­tle more pa­tient. Don’t rush to bot­tle your beer just be­cause the bub­bler on the air­lock stopped bub­bling.

Use a hy­drom­e­ter and make sure you have a sta­ble fin­ish­ing grav­ity for at least a few days. If you can, give it an­other week af­ter you think fer­men­ta­tion is done. This will give you some ex­tra in­sur­ance to make sure fer­men­ta­tion is done be­fore bot­tling and also aid in devel­op­ing clar­ity in your beer.

Fi­nally, it is pos­si­ble that the qual­ity of your in­gre­di­ents led to over-car­bon­ated beer. Low qual­ity or older malt ex­tract, for in­stance, can of­ten fer­ment and fin­ish much more slowly than fresh malt ex­tract, again lead­ing to con­tin­ued fer­men­ta­tion in the bot­tle. The same can hap­pen if you use poor-qual­ity yeast or an in­suf­fi­cient quan­tity of yeast. So when­ever pos­si­ble, only brew with high­qual­ity fresh malt ex­tract and a suf­fi­cient quan­tity of fresh yeast.

Not all dig­i­tal ph me­ters are cre­ated equal. Look for one, such as the Hanna In­stru­ments HALO, that in­cludes tem­per­a­ture com­pen­sa­tion, ac­cu­racy to the hun­dredth dec­i­mal, and a straight­for­ward cal­i­bra­tion sys­tem.

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