Beermaking: Our Process
Many folks visit the Brewery, look through the glass windows, see a lot of shiny tanks, hoses and gizmos, scratch their heads and wonder what they are looking at. What they are looking at is the heart and soul of this business, the reason for our existence as a company.
Before we get to the details, let’s answer some frequently asked questions:
Q. How much beer do we brew in a batch at the Portsmouth Brewery?
A. The “brew length” of our brewery is seven barrels. A barrel is a standard unit of measure in brewing, consisting of 31 gallons. A normal keg is a half-barrel (15.5 gallons). Therefore, we brew 217 gallons (or 14 kegs) at a time.
Q. How much do we make in a year?
A. We brew around 1,000 barrels a year. This is about 31,000 gallons, or a quarter million pints. Strictly speaking, the Portsmouth Brewery is a “microbrewery,” that is, a brewery that produces fewer than 15,000 barrels per year.
Q. How often do we brew?
A. Typically, between 3 and 4 times a week, depending on the season. The rest of the time, we’re doing transfers, cleaning tanks or filling bottles.
Q. Do you bottle your beer?
A. Yes. We bottle limited amounts of beer in 22-ounce “bomber” bottles and half-gallon “growler” jugs. These are available in our retail store and over the bar.
Now, a very brief history lesson
Beer has been brewed for over ten thousand years; for at least as long as humans have called themselves civilized. (It is interesting to note that one of the greatest advances of civilization was also one of the ﬁrst.) Some anthropologists theorize that the production of beer gave rise to civilization in the ﬁrst place. Sound strange? Here’s how the theory goes: Early on, humans were nomadic hunter-gatherers, who were able to scratch out a comfortable enough living by digging up what they could ﬁnd growing wild, or chasing down what they could kill. At some point, a fermented beverage was discovered, most likely by accident when some bread or grain got wet and was allowed to sit around in a vessel and spoil. The early brewers drank this strange “spoiled bread water” and liked how it made them feel. They were able to repeat the process, but in order to have a steady supply of grain, they had to stop their nomadic ways and stay in one place and plant and harvest it. Thus arose the ﬁrst permanent agricultural settlements and the beginnings of human civilization. Though brewing techniques and equipment have improved over the ages, beer still is essentially a sugary extract derived from malted barley, seasoned with hop ﬂowers, and fermented by yeast. The brewer’s art consists of taking four basic ingredients – water, malted barley, yeast and hops – and combining them to create the amazingly wide variety of beer styles available today.
The Raw Materials
Traditionally, beer is made with with four ingredients: water, malted barley, hops and yeast.
Beer is mostly water. We use Portsmouth water for brewing, which tends to be rather hard (mineral laden), a quality, which makes it good for brewing, one of the reasons why brewing was one of Portsmouth’s major industries in the nineteenth century.
Barley is a cereal grain, similar to wheat or oats. Malted barley is grain that has been germinated, then dried in a kiln. In the malthouse, the barley is spread out in a foot-deep layer on a concrete ﬂoor, and sprayed with water. Warm air is blown over it for several days until it starts to sprout. It is then loaded on a conveyor and passed through a kiln, which dries it out and stops the growth process. Some of the malt is kilned longer, causing it to become darker in color, ranging from pale brown to totally black. This is how specialty malts, like caramel, munich, chocolate, and black malts are made. These darker malts are used in beers for color and ﬂavor. Malt is the source of fermentable sugar in beer. Most of the simple sugars extracted from the malt during the brewing process are metabolized by the yeast, producing carbon dioxide and alcohol. The more complex sugars remain unfermented and remain in the beer in the form of residual sugars, which give the beer its body and characteristic malty sweetness. Some beers have a greater amount of residual sugars than others. A bock beer, which is very sweet, has a lot, whereas a “dry” beer is brewed to have virtually no residual sugars, and therefore its “dry” ﬂavor. At the Portsmouth Brewery, we use domestic two-row and six-row malts, as well as some specialty varieties imported from Europe.
Hops are the ﬂowers of a climbing perennial vine. They are used as a seasoning in beer. Hops ﬂowers contribute two things to beer: bitterness and fragrance. We expect the ﬂavor of good beer to be balanced between the characteristic sweetness from the malt, and the crisp, bitterness of the hops. Some beer styles are more bitter than others. Compare our Bottle Rocket IPA, an India Pale Ale, to our Blonde Ale. Which do you think is brewed with more hops? Hops are also responsible for the fragrance in a very fresh beer. Some hops impart a ﬂowery, almost perfume-like fragrance, others are more earthy or spicy. Hops were not always used in beer-making. In early times all kinds of things were added to beer for ﬂavoring: certain tree barks, juniper berries, and ginger root to name a few. Hops were originally put in beer as a preservative, which was very important in the days before mechanized refrigeration. They became widely used in the 1600’s, ﬁrst in Germany and Holland, later in England. Today, dozens of different varieties of hops are grown, each with different ﬂavor traits. At the Portsmouth Brewery we use six to eight different types of hops, depending on the type of beer being brewed. Most of the hops we use come from the Paciﬁc Northwest. Some, notably the Saaz hop – from the Czech Republic – are imported.
Yeast is a single-cell organism which causes the beer to ferment. During fermentation, the yeast consumes the sugars extracted from the malt and produces alcohol, carbon-dioxide and a number of other by-products which affect the ﬂavor and fragrance of the beer. Brewers’ yeast is one of thousands of different types of yeasts, all of which are adapted to live in very speciﬁc environments. Although there are hundreds of speciﬁc strains of brewers’ yeast, they all fall into one of two general categories: ale (top fermenting) and lager (bottom fermenting) yeasts. Ale yeasts ferment at room temperature (65° to 75°). They typically impart certain “fruity” ﬂavors (from compounds known as esters) which are characteristic of most ales. Lager yeasts ferment at lower temperatures (45° to 55°), and generally do not produce the same fruity ﬂavors. Compare our Pale Ale and Amber Lager for a good idea of the different ﬂavors produced by ale and lager yeasts.
The Brewing Process
Let’s follow a batch of beer through the various steps of brewing process.
1. Milling The Grain
To make seven barrels of beer, the different types of malted barley, depending of the recipe, are measured, mixed together and ground into a coarse grist in a mill. A typical seven-barrel batch would require between four and five hundred pounds of pale and specialty malt.
2. The Mash
The grist is augured into the mash-lauter tun and combined with hot water to form a thick porridge, called the mash. This soaks at 149°F for about an hour. During this time, the starch in the malt is being broken down and converted into sugars by enzymes in the grain. These malt sugars are what the yeast will ferment later on. After the mash has sat for forty minutes, sparging begins: 168° water is sprayed on the mash and a the sugary liquid extract, called wort, is drawn off the bottom of the tank and into the brewkettle. We convert and extract about two-thirds of the dry weight of the original grist. In other words, we started with 400 pounds of malt. Two thirds of this weight (268 lbs) is converted into sugar and ends up dissolved in the brew kettle. Afterwards, the spent grain is shoveled out of the mash tun and into barrels and used for animal feed.
3. The Boil
The wort is boiled in the brew kettle for ninety minutes. Bittering hops are added at the onset of the boil and ﬁnishing (aromatic) hops are added at the end. A typical seven-barrel batch of beer would use between two and ten pounds of hops, depending on the style of beer.
After a 90-minute boil, the wort is allowed to stand in the kettle for 30 to 40 minutes. This allows the hops and sediment, called trub, to settle out. Then it is pumped from the kettle, still over 200°, through a heat exchanger, cooling it to 55-65°F. A note: The key to any brewery’s success is scrupulous sanitation practice. The fermenting beer must be completely free of any other microbes except for the particular strain of yeast the brewer is using: no bacteria, no molds, and no other yeasts can come into contact with the beer, because they will contaminate and spoil it. Up to the heat exchanger, sanitation is not a problem because of the high temperature, but as soon as the temperature falls below 160°, the beer is vulnerable to contamination, and every surface it comes in contact with from this point on – pipes, hoses, tanks – must be completely sterile. We use an iodine-based sterilant and hot water to sanitize our equipment.
The chilled wort leaves the heat exchanger and is pumped into a unitank fermenter. A pure, liquid yeast slurry and oxygen are injected as the wort enters the tank. Lager beers ferment at 55° with a “bottom-fermenting” yeast; ales ferment at 68° with a “top-fermenting” yeast.
6. Filtration and Conditioning
After fermentation, the beer – yes, we can call it that now – is chilled in the unitank to 34° and allowed to settle for several days to months, depending on the beer style. Our lager beers generally are passed through a plate-and-frame filter. However, most of our ales remain unfiltered, clariﬁed by allowing the yeast to settle out naturally at a cold temperature, a process known as cold conditioning.
Carbonation is sealed into the beer during fermentation. Any additional carbonation necessary is added in the conditioning tanks. The beer is dispensed directly from the conditioning tanks – there are a total of twelve of them in the brewery’s cold room – to the bar. Ales are served approximately two weeks after they are brewed; lagers four weeks after they are brewed.