Turn on any sink and clean potable water pours out in such abundance that we think nothing of letting it run right down the drain for minutes on end.

Reach in the fridge—or visit nearly any commercial building—and you find milk, juice, water and soda all tasting just the way their producers intended.

As consumers, we Americans (and our many peers in the developed world) have got it pretty good when it comes to the quality and consistency of what we consume. This occurs not just because it is good business, but because many of these products have the potential to cause serious harm through food poisoning or disease transmission. As a result, government regulations and oversight play a major role in determining the packaging and handling of products like water and milk.

Beer is different. And draft beer even more different. It has long been accepted that beer—even bad beer—won’t kill you or make you seriously ill. The unique process and ingredients of brewing delivers a liquid that has been well sanitized and loaded with mild natural preservatives in the form of hops and alcohol. Because of this, the vast body of regulation concerned with beer focuses on government tax revenues and public access to alcohol. Very little regulation at any level of government deals with the safe handling and serving of beer.

Yet despite its apparent hardiness, beer has a vulnerable side. Like milk, bread and hundreds of other grocery items, beer flavor can be greatly changed even while it remains safe to drink. That’s pretty huge when you think about it. Most people consider flavor a key benefit of beer, yet given the susceptibility to taint, beer may be the dietary staple most likely to suffer from off-flavors when consumed.

This article traces draft beer’s journey from the fresh, safe confines of a brewery fermenter to the consumer’s glass in a bar or restaurant. Come along for the ride and see how the beer trade keeps a good pale ale from being transformed into a buttery-sour, hazy goblet of grossness.

From Your Seat…

at the bar, you see the very end of the process: the bartender picks up a glass, opens the tap and fills your beer. If all works well, you receive an attractive, tasty pint.

What should a freshly poured pint of beer look like? For starters it should be topped with foam. And below the head, the glass should be filled entirely with liquid beer. No bubbles should stick to side of the glass below the head. The head should persist as you drink and it should leave lines of collapsed foam on the side of the glass as it empties, forming what we call “lace.”

Many attributes of a well-poured beer depend on draft system maintenance and operation. But to pour great draft beer a bar must begin with a “beer-clean” glass. When cleaned properly, a glass has no soil left adhering to the surface—and no oils left behind from the cleaning process. To achieve this, bars must isolate beer glasses from food dishes and milk glasses and wash them with special low-sud detergents. A cold-water rinse before filling helps too. A beer-clean glass provides the perfect vessel for beer and facilitates head formation and retention while eliminating the potential for unsightly glass-clinging bubbles. Beer drunk from a beer-clean glass will leave the telltale lace of a well-poured beer.

Now, about those bubbles.

In order to form, tiny pinpoints of CO2 must meet, coalesce and combine into a sphere big enough to be seen. When this happens naturally in the beer, bubbles rise quickly to the top of the glass to form the foam or head. But bubbles can also form around fixed meeting points called “nucleation sites.” Clean glass is so smooth it offers no nucleation sites—no place for bubbles to form and stick. Bubbles can only adhere to glass if food, dried beer or other contaminants are left behind after cleaning. Thus bubbles on your glass in the liquid beer flag a poorly cleaned glass. Point them out to your server as soon as you see them and explain that you’d really like your beer in a clean glass.

As for the foam at the top of the beer, it can be a contentious issue between pubs and patrons. Brewers call for up to an inch of foam atop their beers, but consumers—knowing that foam is mostly air—often want that minimized. In Europe, you find beer served in lined glasses. A line, labeled with a liquid volume such as “0.5 Liter,” appears an inch or so below the top of the glass. When presented, your glass should contain liquid beer to that line. The space above that (and often above the top of the glass as well) should be filled with foam.

Behind the Faucet

Draft systems range from simple to complex. But regardless of structure or design, every draft system should deliver cold, carbonated beer. When a server opens the tap or draft faucet, beer should come out as a completely liquid steam that pours at a rate of about 2 ounces per second. In short, pouring a glass of draft beer should be no more difficult or time consuming than pouring beer from a bottle.

New draft systems typically achieve this ideal. But without proper maintenance, the carefully tuned beauty of properly poured draft slips away. In its place, we all too often find out-of-control draft systems that give consumers poor quality beer while also reducing retailer profits.

Draft problems run a range from mild to malodorous based on the consequences faced by both consumer and retailer. Let’s start with the least offensive maladies and work our way up to the truly awful.

Flat Beer: Beers delivered with too little carbonation rarely cause great offense. Indeed, some consumers won’t even notice a flat beer. Still, they support no head or foam and have a dull, lifeless character on the tongue. People will drink a beer with reduced carbonation, but they rarely follow through with another thanks to the subtle signals of poor beer quality. The consumer loses out on enjoyment and the retailer loses beer sales.

Flat beer is more common than you would think. And the problem doesn’t come from the brewery because retailers usually create flat beer with improper draft system management. Here’s why: Normally carbonated beers often get pressurized with the same gas used for nitro beers like Guinness. Because nitro beers have less than half the carbonation of regular beers, the two beers need entirely different blends of gas. (See sidebar: And You Thought They Were Just Bubbles.) When a retailer serves a normal beer on nitro beer gas, they won’t notice any difference at first. But soon physical realities set in—as the keg empties, carbonation leaves the beer. By the time the keg is half empty, the carbonation could well be half of what the brewery intended. Ultimately, the cause of flat beer is inadequate CO2 pressure applied to the keg.

Foaming Beer: Beers that foam leaving the faucet cost retailers money. For starters, foaming wastes a lot of beer as a lot of foam generally goes down the drain. When you dump a pint of “foam,” you lose a quarter pint of beer. Such losses undermine beer—and bar—profitability. Customers lose too. Beer that foams excessively while pouring has lost some of its carbonation and won’t be quite what the brewer intended.

Surprisingly, the biggest problem here usually comes from warm kegs. Most draft systems operate at 38 degrees F. Although few bars realize it, a half-barrel keg that warms up to just 48 degrees F during delivery won’t pour properly. This usually mystifies the bar largely because a 48 degree F keg feels pretty cold to the touch. Unless you realize how exacting the temperature spec is on draft beer, you’ll feel the keg and think, “That beer is cold enough to serve.”

In truth, it takes a full 24 hours in the beer cooler for a 48 degree F keg to reach proper serving temperature. Except in the dead of winter, that means nearly any keg delivered today can’t be served properly until tomorrow. And if a keg warms up to room temperature for some reason, it can take up to two days to chill.

Another problem comes when the entire keg cooler warms up. During the day, cooler doors sometimes get propped open for deliveries or kitchen access. Another source of warming might involve large deliveries of warm goods like bottled water or soda. If beer in the cooler warms up 5 or 6 degrees during the day, all of the beers in the cooler will foam until temperatures drop back into line—a process that can take up to 12 hours.

Beyond keg temperatures, some systems suffer when beer warms up on its trip to the faucet. Draft system designs include beer line chilling, but these may fall short when summer temperatures put more stress on the system or if the cooling system itself is turned off or malfunctioning. Long-draw draft systems—any system where the run from the cooler to the bar is more than 15 feet—rely on a small glycol refrigeration system that typically has two switches: one for the compressor and one for the pump. If one is off, the system can’t operate properly.

If properly chilled beer foams at the faucet, then maintenance may be to blame. Without proper cleaning, lines build up mineral deposits over time. Those deposits change draft system dynamics making it impossible to pour liquid beer at any temperature. Once this happens, lines will need to be rehabilitated with intensive—and regular—cleaning.

Sour/Infected Beer: Poor draft system maintenance affects beer flavor as well. Under the worst circumstances, beer from poorly maintained lines pours hazy, sour and spoiled. It will have a buttery or butterscotch flavor usually mixed with vinegar or—gasp!—slight vomit traits. You might find this when you order beer from a slow-moving draft line or arrive just after opening and get the first pint of the day. Draft lines that pour sour on the first pint or two will give less offensive beer after several pints. Still, “less offensive” is a long way from “good.”

Draft systems that aren’t well maintained negatively affect beer flavor. Most consumers wouldn’t send beer from dirty lines back for being obviously “off”—but they can still tell that the beer doesn’t taste quite right. Thus, they often decide to order a mixed drink or head to a different bar instead. Dirty draft lines hurt business and profits.

Sadly, many retailers still neglect line cleaning. Why? Line cleaning costs money—not only for the service itself, but in terms of beer lost from the lines at each cleaning. Furthermore, many states and communities do not required retailers to clean lines or, if they do, have no effective enforcement. Even in communities with line cleaning mandates and health department inspections of cleaning logs, lines can still get funky. After all, proper cleaning depends on the use of proper cleaning solution, proper circulation routines and sufficient time spent doing the circulation. Cost-cutting line cleaners shave corners and leave lines far from “clean.” Over time, the effect on the lines can be the same as not cleaning at all.

How can you tell if lines aren’t clean? From a consumer’s point of view, draft beer should taste good. No, actually draft beer should taste great. The flavors should be fresh and bright and basically be as good as beer can be. When a beer pours foamy it means it is going to be poorly carbonated. If beer tastes dull or lifeless—especially when compared to the same beer fresh from a bottle, there’s a problem. You’ll have to rely on experience to spot a lifeless beer. Ask yourself if it tastes like it does when it comes from a bottle. Are you missing certain flavor notes? Or have those flavor notes changed? Lobby for proper cleaning or drink somewhere else.

Sadly, in some communities draft system neglect is common. When I asked a group of retailers and wholesalers in a large city I visited last year who did the line cleaning in that area, I got a room full of blank stares. If no one knows who’s cleaning the lines, it probably isn’t being done. That’s not a good sign for your beer.

Neglect can inflict other maladies on draft systems as well, although the ones we’ve discussed above are the most common. On the “really bad” end of things, a small number of bars still dispense beer with compressed air rather than CO2. This approach basically ruins every keg within a few hours of tapping. Another one that I have found is metallic flavors from systems so old that the chrome has worn off of the faucet interiors exposing the beer to brass. You won’t see these often, but when you do, they are reason enough to leave and never come back.

Beyond the Bar

As soon as beer finishes fermentation, it begins to decline. The twin evils of time and temperature take a toll and sooner or later, every beer will taste noticeably different from that “just fermented” flavor. Let’s look at how these issues influence the flavor of draft.

Before craft beer came along, draft beer had a reputation as being beer at its best. The reasons for this are tied up in two issues: pasteurization (or lack thereof) and cold storage throughout the entire distribution chain.

Most breweries ship unpasteurized draft beer. This prevents the slight flavor loss that occurs during pasteurization, but leaves the beer susceptible to microbial infection. To preserve what brewers call the “biological stability” of draft beer, it must be kept refrigerated, so U.S. distribution channels have long been set up to keep beer cold from brewery to bar cooler.

If you visit a U.S. beer distributor, you’ll find a large warehouse that’s maintained at room temperature. Most bottled beer gets stored here to await shipment to a retailer.

Draft beer is a different matter. That gets stored in a nice cold walk-in refrigerator at about 40 degrees F. And, because refrigerated warehouse space is more costly, distributors keep it to a minimum and therefore move the refrigerated inventory more rapidly. That means that in addition to being unpasteurized and maintained cold, draft beer spends less time in transit from brewery to bar and is probably fresher in addition to being better kept.

Among craft brewers, pasteurization is unusual. But larger brewers commonly pasteurize bottled beers. Thus, prior to the craft beer revolution, draft beer had a reputation for being better than bottled product. Today, small and artisanal brewers rarely use pasteurization so bottle and draft leave the brewery at flavor parity. Still, the differences in distribution temperature and turnover persist, so draft may still be the fresher product in most cases.

At the Brewery

We’ve seen how various influences beyond the brewery can ruin the flavor of beer. Of course the brewery itself plays a key role in preparing kegs so that they taste great when they arrive at the bar.

Perhaps the most important part of kegging comes in cleaning returned kegs. Since you can’t see inside them, they must be subjected to an intense sequence of steps that includes caustic cleaners and near-boiling water as well as the occasional acid rinse before a final cold-water flush.

Oxygen is bad for beer so anytime beer gets moved or filled brewers try to minimize exposure to air. Kegs offer a nearly ideal container for oxygen-free fills as they can be purged with CO2 in advance. Furthermore, filled kegs are nearly impermeable to air so oxygen doesn’t seep in during transport and storage.

At most breweries, the cleaning and filling processes are automated to ensure the proper sequence of steps and consistent high-quality results. And of course, brewers know the importance of keeping draft beer cold, so you’ll find filled kegs stored in a refrigerated section of the warehouse until they are shipped to the distributor.

So that’s a look at the key issues affecting draft beer quality. It takes a team effort to put great tasting draft beer in your glass. If any one of the players involved drops the ball, the resulting product can be less than wonderful or even exceedingly bad! As a consumer, pay attention to the quality of the beer you receive and make it a point to patronize places that get it right.

Further Reading

The Brewers Association has an excellent guide to draft beer quality that you can read or download at www.draughtquality.org. This is a highly recommended resource for people in the trade.

Those who want to know more about the presentation of quality beer might consider participation in the Cicerone Certification Program. For more information, see www.cicerone.org.