Ask the Troubleshooter
Dave Miller on...
Water Hardness, Dextrin Malt, Malt Shelf Life, and Careers in Brewing

by Dave Miller
Republished from BrewingTechniques' May/June 1994.

This issue, The Troubleshooter gives a quick primer in basic water chemistry, explains how dextrin malt "works" to add body and mouthfeel to beer, discusses malt shelf life and storage, and advises would-be professional brewers on the challenges of turning pro.

Water Hardness

Q: After seeing references in various beer publications and books on water analysis, I decided to contact my local officials and get a copy of the breakdown for our local water supply. The contents of the report indicate that carbonates are <1 ppm and that bicarbonates are 160 ppm. My reference material discusses carbonates but not bicarbonates. Should I treat carbonates and bicarbonates as the same thing?

One person told me that the amount of bicarbonates in water is related to temporary hardness. If this is so, in comparing my water supply to other water supplies in various parts of the world, do I look at the initial hardness of my water, or the hardness of my water after it has been boiled? Is it true that adding chalk to water raises temporary hardness? If so, does it matter when I add chalk to the boil? If it's going to precipitate out, why add it at all?

One last question: When I use my copper wort chiller the liquid changes the copper coils from a dull color to a bright finish. Is my wort too acidic?

DM: In a sense, carbonates and bicarbonates are the same; in another sense, they are not. They are the same because they freely change from one to the other, depending on the pH of the water in which they are found. In low-pH water, such as yours, carbonate ions are scarce. Raise the pH of that water, and some of the bicarbonate ions would become carbonate ions.

Carbonate and bicarbonate differ, however, in that bicarbonates are considerably more soluble than carbonates. Calcium carbonate (chalk), for example, is only slightly soluble in neutral (pH 7) water; calcium bicarbonate is considerably more soluble.

Now let's talk about hardness. Hardness, strictly speaking, refers to a water sample's content of calcium and magnesium ions. (For the rest of this discussion, I refer only to calcium, just to keep things simple. In general, magnesium resembles calcium in its behavior, except that magnesium salts, including magnesium carbonate, are somewhat more soluble in water than are calcium salts.) Permanent hardness is hardness that cannot be removed by boiling the water. Temporary hardness is hardness that can be removed by boiling. In temporary hardness, most of the hardness is attributable to calcium bicarbonate. Boiling such water causes the bicarbonate ion to become a carbonate ion, which then binds with calcium. Calcium carbonate is almost insoluble, so it precipitates, thus removing both calcium and carbonate from the water. Because carbonate is alkaline in character, the alkalinity of the water decreases at the same time.

In effect, boiling water like yours will reduce the carbonate/bicarbonate ("total alkalinity") from 160 ppm to 30-40 ppm. This is very significant because it will enable you to brew pale beers. As is, your water is best suited for making very dark beers, such as stouts and porters, which use a large amount of dark, acidic malt.

In comparing your water to other water supplies in the great brewing cities of the world, you should probably compare the initial carbonate/ bicarbonate content. Traditionally, brewers did not preboil their water. However, you can also estimate the hardness (calcium content) and alkalinity (carbonate/bicarbonate content) of your postboil water and compare those figures with various brewing waters of the world. For estimation purposes, figure that for every 5 ppm of carbonate you remove you also remove 3 ppm of calcium. In your case, assuming you aerate the water thoroughly before boiling, you can precipitate ~125 ppm of bicarbonate, leaving ~35 ppm in the water. At the same time you would reduce the calcium content by about 80 ppm.

Though you can do the comparisons, it is best not to get too devoted to the idea of duplicating the water of a particular brewing center. It may not be possible, especially in the case of very soft water like that of Pilsen - at least, not without distillers or deionization filters. Also, it is unnecessary and may not even be desirable. To continue with the Pilsen example, if you duplicate Pilsen water, you will also have to duplicate the Pilsener brewing method, which is a triple-decoction mash that takes 5 h to complete. The decoction mash is necessary to lower the pH of the mash and to get a good conversion reaction. If you tried to use an infusion mash with this water supply, the mash pH would be too high. It is perfectly possible to brew Pilseners with the infusion method, but you must have a calcium content of 50-100 ppm combined with very low total alkalinity (<75 ppm). In other words, your soft water would work, but you would have to add calcium chloride or calcium sulfate to the mash.

Adding chalk to water does not increase temporary hardness, for the reason already given: calcium carbonate is almost insoluble in neutral or alkaline water. There is no reason to add it to the water before boiling. If you need to add carbonate to raise the pH of the mash, you must put it directly into the mash. A dark malt mash is more acidic than a pale malt mash, and carbonate will dissolve in the mash and raise its pH. This treatment, however, is needed only when using water of very low alkalinity and low pH.

To answer your question about the wort chiller, the mildly acidic wort dissolves the surface layer of corrosion on the copper coils. This reaction is normal and does not mean your wort is too acidic. The same thing happened to me and I checked my wort with a pH meter. It was fine.

Dextrin Malt

Q: Is it correct to assume that all extract from dextrin malt is in the form of dextrins and therefore not fermentable? If dextrin malt is mashed with other malt, will the enzymes in the other malt convert the dextrins to fermentable sugars? How much dextrin (when added to a typical batch size) is appropriate for a "full-bodied" beer style? What type of extract should I expect from dextrin malt?

DM: Dextrin malt is made by a complicated process that is proprietary to the manufacturer, Briess Malting Company. Basically, the malting conditions are so manipulated that the sugars and dextrins are changed into nonfermentable isomers that also cannot be attacked by the malt enzymes, alpha and beta amylase. This means that, no matter how long the dextrin malt sits in a mash tun, little or no breakdown will occur. In addition, virtually all of the carbohydrates extracted from dextrin malt are unfermentable. These characteristics make dextrin malt an almost ideal "body builder" for beers.

I say almost ideal because, in my own experiments, I found that using very high proportions of the material can impart a starchy flavor note to the beer. When kept to a reasonable level, however, any flavor change is so slight as to be virtually undetectable. I recommend amounts of up to 0.5 lb/5-gal batch. You can go higher, but this level seems to give sufficient body enhancement, even to low-gravity brews.

Dextrin malt is most useful in lager beers because lager yeasts use more of the triple sugars in wort and thus generally give a lower terminal gravity, and a lighter body, than ale yeasts working on a wort of similar starting gravity. At the Saint Louis Brewery, we use dextrin malt to improve the mouthfeel of our Pilsener. It seems to give about 30 points specific gravity/ lb/gal - a few points lower than pale brewer's malt.

Storing Malt Extracts

Q: I love quantity discounts on malt, but do malts have limited shelf life? I assume cool, dry storage is best, but is this the same for dry malt extract? Liquid extracts? Should I refrigerate or freeze?

DM: Malt, like almost any food product, is perishable. Whole grain malt, however, will keep for six months or more if it is stored in cool, dry conditions. Preground malt is less stable, because crushing strips away the tough protective husk and exposes the interior of the grain to airborne moisture and mold spores. Nonetheless, even preground malt will keep for a couple of months if it is stored in airtight bags. By the way, the bags in which preground malt is packed are very good these days.

Malt extract is likewise fairly stable, but not everlasting. Dry malt extract will show deterioration by absorbing moisture from the air and hardening. I have seen it keep for a year when stored in a very dry room packed in a double layer of airtight plastic. Liquid malt extracts, on the other hand, seem to slowly deteriorate in the can or drum from the day they are packaged. Very old malt syrups become dark and acquire a coarse, molasses-like flavor that is obvious in beers made from them. You can do little to extend the life of malt syrup by your own packaging or repackaging. About all you can do is keep it at moderate temperatures (60-80 °F) and use it within six months.

I do not recommend freezing or refrigerating malt in any form. Unlike hops, they do not keep better under cold storage. I do, however, recommend storing opened packages of malt grain or dry malt extract in a tightly sealed container and with a few packets of silica gel desiccant. You can get these things in the notions department of department stores, and they last forever if you occasionally redry them in the oven. Dry air and moderate temperatures will give your malt the longest possible shelf life.

Careers in brewing

Q: I am a home brewer and would like to get into brewing professionally. Do you have any advice on how I should proceed? Should I take a course at the Siebel Institute or the University of California-Davis?

DM: I get this question about once a week. It's really hard to answer without knowing more about you, because everybody is different. The answer really depends on your age, your educational background, your marital and financial status, and a host of other things.

The first thing you have to realize is that a lot of other people have the same dream. They love beer and are obsessed with brewing. They can't imagine anything they'd rather do for a living. And I agree with them.

On the other hand, the fact that so many people have the same dream means that a lot of potential microbrewers are chasing the relatively few jobs. When supply exceeds demand, the price of any commodity, including labor, goes down. In other words: you are not likely to make a lot of money in this business.

Another thing you need to realize is that when you do it for a living, your attitude toward brewing will change. You'll still enjoy it, and you'll feel proud of your product, but the fact remains that it's possible to get enough of anything. When I leave work these days, many times brewing is the last thing I want to think about. The way I usually put it is, "I had the greatest hobby in the world, and I had to go and turn it into a job."

Also, there is a lot of responsibility for such a low-paying job. When you make homebrew, an infection is a terrible disappointment. All that effort down the drain. But in a microbrewery, an infection is a catastrophe. It usually means the loss of several batches of beer, which in turn means that you are liable to be out of product for at least a week or two. So you have to be more than a talented, creative person. You have to be meticulous, methodical, and willing to put in whatever hours it takes to ensure that the mindless, repetitive task of cleaning and sanitation is done right, every time. Much of the actual process is like that: it is essentially rote, yet you have to keep your mind on it.

Finally, the job takes a physical toll. Good brewery design can go a long way toward minimizing the amount of hard labor needed to turn out a batch of beer, but even a well-designed micro usually needs lots of muscle work. Like most small businesses, micros are usually strapped for cash, especially at start-up. This means that they cannot spend a lot of money on mechanization. Tasks like mash agitation and grain disposal are done the old-fashioned way - by hand. A lot of micros brag about their "hand crafted" brews; back-crafted, shoulder-crafted, or leg-crafted are nearer the mark. The work grinds you down.

OK. You're sure you want to do this. Then here is my advice. First, learn as much as you can. That means taking one or more courses at Siebel or Davis. But before you enroll, prepare yourself. Read all the brewing books you can get your hands on. If you have read, and understood, George Fix's Principles of Brewing Science, you can be confident that the technical lectures at brewing school will not go over your head. On the practical side, go as far as you can in your home brewing. That means all-grain brewing, yeast culturing, the whole nine yards. Mashing is mashing, whether you're making 10 gal or 10 bbl. If you have never seen a mash, never felt how it thins out as the starch converts, you won't get nearly as much out of a formal class on the subject. And considering how much they cost, you will want to get as much out of your brewing courses as you can. The price of a full-bore all-grain home brewery is quite modest compared with the price of formal instruction, and although you will learn things in the classroom that you would never learn by the seat of your pants, the opposite is also true. Take recipe formulation, for example. The only way to really learn what a particular grade of caramel malt will do to the color and flavor of a beer is to brew with it.

You should also get into the Beer Judge Certification Program. Microbrewing is, in a lot of ways, more like home brewing than it is like industrial-scale brewing. You have to be familiar with the range of beer styles brewed in Western Europe, with a good understanding of what makes them taste the way they do. Also, you need to learn how to evaluate beers by using your senses - sight, smell, and taste. Part of that evaluative skill must be an ability to discern the various types of off-flavors that arise in beer. Since micros lack the huge technical departments of the large industrial breweries, a microbrewer has to use his or her senses as the basis of the brewery's quality control program. Those areas of knowledge and skill are precisely the ones you must learn in order to become a beer judge. I recommend the program highly.

That is the best advice I can give, not knowing your personal situation.

If you think the goal is worth pursuing, don't do it half-heartedly. Good luck.


I wish to thank Mary Anne Gruber at Briess Malting Co. for providing helpful technical input for the answer to the question on dextrin malts.

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