The history and science of Goses | Part 2

Anderson Valley Brewing Co. in Boonville, Calif., makes some awesome Goses. In fact, Brewmaster Fal Allen wrote a whole book on them. So who better to submit 6,000+ words on the topic? Part 1 covered the entire history of the Gose to this point — from the dawn of humanity to its fairly recent revival. Here, Fal gets nerdy about the technical specifications.

The flavors and aromas listed here are for Gose beers made without additional flavorings such as non-traditional spices or fruit additions. Obviously additions of fruit or spices will greatly alter the beer’s flavor profile. The fact that Gose-style beers easily lend themselves to being flavored with spices or fruit makes it difficult to cover all possible flavor variations here.

Gose technical specs

Original Gravity (OG): Goses are not big beers, your starting gravity should be no higher than about 14°P (1.057), and could be as low as 8°P (1.032). A typical starting gravity for Gose should be about 10°P (1.040).
Final Gravity (FG): A Gose should finish dry, between 1.25°P (1.005) and 3°P (1.012), and certainly not above 3.25°P (1.013). Typically final gravities should be about 2°P (1.008).

Acidity & pH

Since acidity is such a big part of Gose’s flavor, we will discuss it before looking at the other specifications the beer’s profile. Acidity is the main thing that has defined the beer style since its beginning. And as such, one needs to know a little about acidity, how it is measured, and how it works.

There are two ways to measure acidity, namely pH and titratable acidity (TA). We will only discuss pH here as TA is less often used and is more complicated. Acidity is the effective strength of an acid (or a base) in solution. We use the pH scale to measure that concentration. For the more scientifically minded, pH is the negative log of the activity of free, dissociated hydrogen ions (H+) in an aqueous solution.

Brewers have been using the pH scale since soon after it was developed at the Carlsberg laboratories in Denmark in 1909. The p stands for “power of” or “potential of”—the H stands for Hydrogen, and is a measurement of hydrogen ions in a concentration. The pH scale runs from zero (very acidic) to 14 (very alkaline or base) with a measurement of 7.0 being neutral. Pure distilled water is pH 7. Thus a pH below 7 is acid, and a pH above 7 is alkaline.

The pH scale is logarithmic, and uses an exponent of 10. Each increase or decrease of 1.0 on the scale indicates a ten-fold change of pH. Thus a solution of pH 4 is 10 times more acidic than a solution of pH 5 and 100 times more acidic than a solution of pH 6. Remember the lower the number from 7, the more acidic it is.

Temperature will affect pH. All pH readings should be taken at or calibrated to a temperature of 77°F (25°C). As the temperature rises, pH decreases. For example at 32°F (0°C), the pH of pure water is an alkaline 7.47. At 77°F (25°C), its pH is a neutral 7.00, and at 212° F (100°C) its pH is an acidic 6.14. Be sure to adjust your pH reading accordingly if your solution is greater or less than 77°F (25°C).

The pH range for most finished, non-soured beers runs between 4.0 and 4.5. For sour beers the range will run about 2.9 to 3.9 pH. Sourness in Goses should be low to medium high, but should complement the overall beer. The pH should fall between 3.2 and 3.6. It should produce a lively and bright acidity, not a mouth puckering sourness

Flavors

Gose is a tart wheat beer with low bitterness and a restrained touch of seasoning, most often that seasoning is coriander. This beer is brewed with both barley and wheat in equal amounts and the flavor reflects this mix. The beer should have a light bready flavor and aroma. The beer also has a mild salinity (discussed later). The overall impression from the salt should be a light mineral quality and not one of saltiness. Gose-style beers usually have a high level of carbonation and a bright acidity. This tart acidity is the result of lactic acid and this is often described as a lemon or citrus tartness. Bitterness should be low and generally go unnoticed. Bitterness

Bitterness should be between 5 and 15 IBUs—although some brewers in the United States have produced hoppy Gose-style beers. The hoppy versions fall far outside the guidelines of the Leipzig-Gose tradition. I find that the acidity of the Goses clash with a high bitterness and that that clash interferes with the thirst quenching drinkability of the style.

Gose-style beers have bright, sharp flavors that make them refreshing to drink. They are highly attenuated and should finish dry and crisp, never full-bodied or flabby. The restrained acidity and sourness should balance the bready, doughy, wheat malt character.

Aroma

Gose-style beer aromas are often light to moderately fruity. The malt aroma is reminiscent of sourdough bread dough. There may be a cider quality to the overall aroma. The use of coriander can give the beer a floral and sometimes lemony note. These coriander notes, when mingled with the fruitiness and sourness, create a pleasing aroma. Hop aroma should be low and when noticeable should complement the other aromatic components. The fermentation (both bacterial and yeast) should be clean, with no to very low levels of “funkiness.” The aromatic qualities should be mild to moderate and should blend together to create an overall impression of being fresh and spritely.

Color

The color of Gose should be relatively pale; very light straw to medium amber color, in the range of 1.5 to 6.0 SRM (3 to 12 EBC). Traditionally they were called white beers. This originally came from the use of “air dried” malts that are not commercially available today. The color might be a little higher if a brewer decides to use a small amount of specialty malt, but this would not be considered traditional. The typical Gose beer is light golden with a white head.

Goses are unfiltered wheat beers and as such some haze is acceptable, they will be hazier than modern German style Pilsners but they should not be as hazy as a hefeweizen-style beer nor a modern new England IPA. They should be in the range of about 8 – 25 Turbidity Units (NTU), but they could be as low as 4 to as high as 600 NTU. They definitely should not be milky or opaque.

Mouthfeel

The body of these beers is light to medium-full. The overall impression for these beers should not be heavy. High carbonation levels should lend a pleasing effervescence, on the higher side of 2.55–3.0 volumes. It may have a good head from the wheat, but due to lactic acid fermentation, some may also have very little foam at all. The issue of low foam can be rectified by starting wort souring at a pH <4.5 (or lowering very quickly to below pH 4.5). This will help keep the protease enzymes that cause foam degradation from being active

Alcohol

The alcohol by volume (ABV) on these beers is fairly low, between 3 and 5 percent. This corresponds to the low original & finishing gravities mentioned above.

Ingredients

Many things play a part in the formation of the final beer’s flavors: specific processes, time, cleanliness, equipment design, the brewer’s skill, and ingredients. None can be more important than good ingredients, particularly the water and the yeast you will use. Without good ingredients it is very difficult to make delicious beer—and as brewers, that is always the goal.

Malt | Malt for Goses should be pale in color. Traditional Goses are made using 50% barley and 50% wheat. These proportions can vary some, but keep in mind that Goses are wheat beers and as such should have a relatively high percentage of wheat malt. Since wheat is a naked grain (no husk) this may cause problems in lautering. To rectify this problem a brewer can use a small percentage of rice hulls (5 – 10 %). Sometimes a small amount of oats can be used (about 10%).

Hops | Goses are not hop-forward beers. One reason that Goses are not hoppy beers is that Lactobacillus is not a hop-tolerant bacteria. As little as 5 IBUs can affect the growth of Lactobacillus, and without Lactobacillus, Goses will not be sour. This is less of an issue if you are doing a brewhouse souring of your Gose, but still keep in mind that Gose are light beers that are balanced and refreshing. Too much hop bitterness will throw these light beers out of balance.

Water | For brewing – If you like the way your water tastes then it will be an acceptable base for brewing beer. As to Goses – We know from many historical sources two things about Gose 1) that the water of the Gose River which runs through Goslar was used to brew the Gose beers and 2) that the Gose beer had a noticeable mineral note or salinity. The waters of the Gose River are not very high in minerals or salts, so where then did the salt in the Gose beer come from? It was probably added to the beer to create more body.

Salt | It has been suggested that the salinity in Gose beer once came from the mineral-laden water of the River Gose. Today we know that not to be the case. Unlike other regions of the world at that time, salt was plentiful in the area around Goslar, and thus was not the expensive commodity it was in other brewing centers. We do know that brewers have at times added salt to enhance body and fullness of their beers. These reasons are probably why salt was first used in Goses. We know that later as the beers from Goslar gained in popularity, brewers in the nearby towns wanted to emulate their unique character. In order to replicate the Goslar’s famous Gose flavor, brewers needed to replicate that mineral salinity. From brewing records, we know that the solution for many of those brewers was to add a little salt.

There are many varieties of salt, and you probably should decide what kind of salt you want to use before you decide how much of it you want to use. Salt’s chemical makeup, in its purest form, is sodium chloride (NaCl) in a 2:3 ratio of sodium and chloride ions. Thus 100 g of sodium chloride (salt) contain 39.34 grams sodium and 60.66 grams chloride. Minerals or compounds bound up with the salt are what gives different salts different flavors and colors. There are many varieties of salt to choose from, but once a salt is dissolved in either food or beer, it is pretty unlikely that any difference could be easily distinguished. The mineral content in most salts is so low that any effect these minerals might have on flavor will be lost when even as much as 1 oz. (28 g) is mixed into one gallon (3.78 liter) of beer. This leads me to believe that the value of using an esoteric and expensive salt in a Gose would be almost entirely marketing. For brewing Gose I would suggest an affordable non-iodized sea salt.

I believe that in most of brewing, more can often end up being less. It’s a tricky thing; one wants the ingredient to be noticeable, but only enough to make the beer interesting. Salt’s flavor contribution should accentuate other flavors and enhance mouthfeel, not create a salty brew. For some historical perspective, we know that some Goses from the early twentieth century had between 130 and 280 ppm of salt. At Anderson Valley we use a bit more; about 800 ppm of hydrated salt added post fermentation. That is a bit more than some historically, but below the threshold of where it would negatively affect the beer. This gives our Goses a noticeable salinity but certainly not a salty taste.

Spices | When Goses were first brewed in the Middle Ages, hops were not yet in use, there were, instead, many herbs and spices used in brewing beer. There may have been many spices once used in making Goses but the two that were most noted in the historical record were coriander and sometimes spruce. Of these two, coriander was the one that remained in use even up into the 20^th century. Regardless of what (if any) spices a brewer chooses to use as with salt, a spice’s contribution to the overall beer should be in a supporting role. You want to add enough spice to lightly accent the beer, but not overpower the other flavors.

Fruit | Traditionally fruit was not added to Gose, but as with Berliner Weisse, flavored syrups were sometimes added to the beer at the point of service. Modern brewers have taken that concept and run with it by adding fruits, both natural and as purees, syrups, or flavorings, to the beers before packaging. The potential flavor combinations are nearly limitless.

The fruit a brewer adds will contribute flavor, but also some fermentables. Most fruits contain a mixture of sugars: fructose, glucose and sucrose.

The pH of fruit can vary from 4.5 to as low as 2.1 for some citrus fruits. You should bear this in mind when adding fruit to beer. In the case of Gose, a fruit addition might even raise the pH.

Fruit may also bring color to the beer. Most of these colors will be pleasing, but not all. Be careful when using fruits that contain seeds, pits or skins. These parts of the fruit can cause unpleasant astringency or off flavors. I recommend tasting these components by themselves and deciding if you think it worth the extra effort of removing them from the fruit. The rind, peel, skin and seeds can contain compounds that impart harsh and unwanted flavors—sometimes even toxins. In most cases, I think it is worth the trouble to peel, pit or de-seed the fruits.

In my experience fresh fruit almost always tastes best, but fresh fruit has many drawbacks. It is labor intensive to process; peeling, squeezing, zesting, chopping, pureeing, scooping, and mixing. It can be hard to acquire a sufficient amount (when out of season). It does not store well.

Other options include (in descending order of preference) frozen whole fruit, frozen purees, frozen pasteurized purees, pasteurized juice, pasteurized aseptic non-frozen purees, juices, juice concentrates, extracts, natural flavoring, and artificial flavorings.

Each of these has pros and cons. As you descend down that list from frozen whole fruit to artificial flavoring, the quality of the flavor decreases as the ease of use increases. One nice thing about using purees, juices, or extracts is they have removed most of the extraneous matter (seeds, pits, stems, etc.). Whichever of these forms you choose, be careful to find a vendor with flavors that you like; puree, juice, syrup, and extract can vary widely in flavor and aroma from one supplier to the next.

Hot Side Fruit Additions

The advantage to adding your fruits on the hot side is that they are sterilized by contact with the hot wort. The down side is that there may be a loss of some of the subtle and more delicate flavors and aromas during the boil, whirlpool, or steeping. Boiling fruit may also create a more cooked jam-like flavor. As with spices, the best way to add fruit on the hot side is at the very end of the boil—just long enough to sterilize the fruit in the whirlpool.

Cold Side Fruit Additions

Adding fresh fruit to your beer on the cold side can give your beer the flavors closest to real, fresh fruit. As with spices, the down side to adding fruit at this time is that it has not been sterilized. Fresh fruit has a lot more both micro and macro fauna. Adding fresh fruit to beer on the cold side may dramatically increase your chances of infection. To alleviate some of this potential, brewers often use frozen fruit, as most bacteria cannot survive any length of time in the deep freeze—but some can. Safer yet are flash-pasteurized fruit purees that have then been frozen, and even safer are fruit concentrates.

The closer to the beginning of fermentation you add your fruit, the more fruit flavor and aroma is lost to carbon dioxide creation during fermentation. The obvious way to avoid losing aroma and flavor this way is to add the fruit when fermentation is very near the end or completely finished. If the yeast are dormant or removed this may leave fruit sugar in your beer. This additional fruit sugar will not only make the beer sweeter, it will leave unfermented sugar in the beer which can lead to infections, gushing bottles or foaming kegs, or worse exploding bottles or cans.

If a brewer wants to get fruit flavor and aroma, but does not want the sweetness from the fruit sugar add the fruit in the last 20–30 percent of fermentation and this will allow the yeast to consume most of that sugar.

Yeast | For Gose, the choice of yeast is not as dramatic as for other beers. Goses are traditionally top-fermented ales, so although lager yeast could be used, it is not the best choice. I would recommend a German ale strain—perhaps Kölsch or Altbier yeast. One could also use an English ale yeast, but I would avoid ones that are overly fruity. Pick a yeast that ferments dry and with a low fruitiness. Kveik yeast would be an interesting choice and make a good Gose.

Bacteria | Lactic acid is one of the defining flavor characters of the Gose style. The lactic acid in the beer is derived from lactic acid bacteria (LAB). The Lactobacillale (LAB) family include Lactobacillus, Pediococcus, Lactococcus, Leuconostoc as well as several other lesser-known varieties. Lactobacillus is the most used and most known and understood of the LAB. Lactobacillus can be found throughout nature on fruits, plant material and grain husks, in human and animal mouths, and in digestive tracts and skin. The genus Lactobacillus contains around 180 known species.

Most species of Lactobacillus are not hop tolerant. Below, some of the more common choices of Lactobacillus are:

L. delbrueckii: (often used in yogurt production) clean, lactic sourness. Known for heat tolerance.
L. Acidophilus: heterofermentive, micro aerophilic, used in soured dairy products like yogurt. Known to inhibit other organisms’ growth.
L. Plantarium: aerotolerant, will grow at lower temperatures of about 60°F (16°C) has some difficulty performing above 115°F (45°C). Heterofermentive, can produce other by products (CO₂, alcohol, acetic acid). Does not like hops. Very high tolerance to low pH (~3.0)
L. Sanfranciscensis: Important in sourdough production, produces dough notes.
L. buchneri: heterofermentive, may produce acetic acid.
L. Casei: has a wide pH and temperature range. Used in cheese production. Ferments lactose, maltose,

The source for your LAB can vary as well. Most people get their bacteria from a laboratory like White Labs or Wyeast Labs. Some choose to pitch live active yogurt into their beer. Others use probiotics like Good Bellies. And a few use the LAB that exist on grains to sour their beer. This later is a tried and true method known in Germany as Sauergut. Whatever the source you decide to use for your bacteria, it is very important that you make a starter and grow up a proper amount to pitch into your wort. The amount should be similar to the proper yeast pitching rate for a wort – approximately one million cells per milliliter per degree plato of the beer. The optimal temperature range for LAB to grow is 95–120°F (37–49° C).