Malt is a grain product produced by soaking grains in water to make them germinate, and then drying and baking. Beer brewing generally uses barley malt, and sometimes other grains and their products are also used. Adding different grains will bring different effects. For example, wheat malt and oats will make the taste of beer smoother and fuller, while rye will bring a slight spicy feeling. During the saccharification process, due to the action of amylase, the starch in the malt is broken down into fermentable sugars and non-fermentable sugars. The fermentable sugars are then metabolized by yeast to produce alcohol, carbon oxides and flavor substances.
According to its role in beer brewing, malt can be divided into basic malt and special malt. Basic malt has certain enzyme activity, sugars and proteins, which provide guarantee for subsequent healthy fermentation; special malt does not have enzyme activity and is difficult to provide guarantee for fermentation, but it can contribute color and different flavors to beer. Therefore, for most beers, the amount of basic malt is greater than that of special malt.
According to different processing processes, malt can be roughly divided into the following categories:
| Malts | Process | Example | |
| kilned malts | It is dried in a kiln and roasted at a lower temperature. It is equivalent to basic malt in the definition of this book. | "Pilsner malt, pale ale malt, Vienna malt, Munich malt, smoked malt" | "Sweet, cereal, biscuit, toast, bread, nutty, smoky (smoked malt)" |
| roasted malts | After the kiln treatment, the dried malt is placed in a roasting oven and roasted at a higher temperature to inactivate the enzymes in it. This is a type of special malt. | "Biscuit malt, chocolate malt, dark malt" | Biscuit, chocolate, coffee, caramel bread |
| caramel-type malts | "Wet malt ("green malt") is not dried, but directly placed in a kiln or roasting oven (kiin) for heating, so that the starch is saccharified in the husk, and the temperature is continued to rise to make it caramelized. This is a type of special malt. | Caramel malt (can be roasted in a roasting oven or a roasting oven), crystal malt (must be roasted in a roasting oven) | Caramel, toffee |
In addition to germinated grains, some ungerminated grains are sometimes used for brewing, including barley, corn, rice, wheat, rye, oats and sorghum.
A study in 2022 showed that malt can be clearly traced to 46 sensory characteristics, including 26 flavor characteristics, 15 appearance characteristics and 5 taste/mouthfeel characteristics.
Hops, also known as hops, are the inflorescences of Humulus lupulus, a climbing herb of the genus Humulus in the Cannabaceae family. Its female cone-shaped flowers can be used to brew beer, so the hop plant is sometimes also called hops. Although beer brewing has a history of tens of thousands of years, it was not until the 9th century that brewers began to use hops. Hops gradually became popular in the next few hundred years and became the basic raw material for beer brewing.
Initially, brewers added hops mainly to use its antibacterial properties to extend the shelf life of beer. The female hops used for brewing contain lupulin glands, in which the resin (containing alpha and beta acids) provides bitterness, which complements the sweetness of malt and makes beer easier to drink; essential oils provide flavor substances, providing beer with rich aroma and taste.
There are many types of beer, and so do hops; the Homebrew Academy has included more than 150 types of brewing hops. According to their functions, hops are divided into aroma type (mainly contributing to aroma), bitter type (mainly contributing to bitterness) and bitter and aroma type (both aroma and bitterness).
As a crop, the flavor of hops reflects the local terroir (natural conditions) and human feelings (cultural aesthetics). Similar to wine, hops are also called "New World" and "Old World". The former includes continental Europe (mainly Germany and the Czech Republic) and the United Kingdom, while the latter mainly includes the United States, Australia and New Zealand.
Continental European hops have the longest history of being used in winemaking. The flavor is relatively elegant, usually with herbal, floral, and herbal aromas. The most famous are "noble hops", such as Saaz, Hallertau, Tettnang, and Spalt. English hops usually also have floral aromas, as well as "earth" flavors similar to wood and soil. Common types include Fuggle, Kent Golding, Target, etc.
As the birthplace of the modern craft brewing movement, the United States has a very diverse culture, and so do American hops. Today's American hops have prominent flavors such as citrus, tropical fruits, and pine needles, which has given birth to many hop-oriented IPA beers. There are many varieties of American hops. In addition to the classic "4℃ hops" - Cascade, Columbus, Centennial, Chinook, there are new varieties like Citra, Simcoe, Mosaic, Amarillo, Idaho 7 and Strata, which provide more distinctive flavors.
Australian hops are similar to some American hops, and the fruity flavor is also more prominent. The most famous Galaxy has the flavor of passion fruit and peach. There are also Topaz, Enigma, and Victoria's Secret, which are all representatives of Australian hops. New Zealand hops often bring interesting cross-border experiences - Nelson Sauvin reflects the flavor of local Sauvignon Blanc wine; Motueka has a very unique lime flavor, reminiscent of Mojito.
Yeast refers to various single-celled fungi that can ferment sugars, belonging to the Eukaryota domain, Fungi kingdom. Alcohol in beer is the metabolic product of yeast.
There are more than 1,500 known yeast species. Beer yeast is mainly divided into two categories: ale yeast and lager yeast.
The fermentation broth is the liquid in the process of converting wort into beer. Although yeast exists in the fermentation broth as a whole, most of the lager yeast gathers in the lower layer of the fermentation broth during fermentation, so it is also called bottom fermentation yeast. Lager yeast usually works at a lower temperature (8~13℃), has a long fermentation time, and the fermented beer is clear and tastes clean. Beer brewed with lager yeast is called lager beer.
Ale yeast gathers in the upper layer of the fermentation broth during fermentation, so it is also called top fermentation yeast. This type of yeast prefers to work at higher temperatures (generally 13~24℃), and some ale yeasts (such as Kveik) can work at temperatures as high as 43℃. Ale yeast ferments faster and produces rich and varied flavors such as fruity and spicy. Beer brewed with ale yeast is called ale beer.
In addition to ale and lager yeast, there is a relatively niche but unique fermentation flavor of Brettanomyces, also known as wine yeast. This type of yeast can be found on the skin of fruits and plants, and also exists in the air. After a long period of fermentation (usually more than a year), Brettanomyces will produce a "funky" smell similar to a barn, a stable, and a wet rag. The fermentation process of wild beer (wild beer) that many craft beer lovers like to drink almost all involves Brettanomyces.
Wild beer is not necessarily sour, and sour beer does not necessarily involve wild bacteria in fermentation. The sour beers we often drink now, such as Gus beer and Berlin sour wheat beer, basically use the method of artificially adding lactic acid bacteria and quickly acidifying wort. The common process is called kettle souring, which is to add lactic acid bacteria after the saccharification is completed and the wort is collected. There is also a new process called sour mashing, which adds lactic acid bacteria during the saccharification process.
More than 90% of beer is made of water, but the effect of water on flavor is often overlooked. Different malts have different flavors, but malt is used after being heated and saccharified with water to make wort. The characteristics of brewing water greatly affect the aroma, taste and mouthfeel of wort. The ions in water are an important factor affecting the perceived bitterness of beer, and trace elements (such as chlorine) are also common factors that cause beer odor.
Brewing water needs to be clean and odorless. For most beer styles, the water also contains trace amounts (but not excess) of various ions. Water usually comes from surface water (lakes, rivers, streams) or groundwater. The mineral content in surface water is usually appropriate, but other biomass such as algae is relatively high, so it needs to be filtered and sterilized before use. The biomass content in the underground is low, but the mineral content is too high, so the minerals need to be adjusted before use. We have all heard some beer manufacturers claim that their products are "brewed with spring water" - if it is indeed spring water, that is, clean surface water with low mineral content, then it is indeed an ideal brewing water.
The water in each place is different. In the past, brewers had limited ways to adjust water, and the beer they brewed naturally had the characteristics of the local water quality, which formed the style of the place over time.
For example, the water source of Pilsen, located in the western Bohemian region of the Czech Republic, has a low mineral content, that is, it is very "soft", which is particularly suitable for brewing beers such as Czech pale lager. The world-famous Pilsner beer was born here and named after its city; and in Burton-upon-Trent, England, the water source has a very high calcium sulfate content, which is particularly suitable for brewing IPA beers with a dry and crisp taste and full hop flavor. The water source in Dublin, Ireland is highly alkaline, which is particularly suitable for brewing dark beers with a smooth taste (such as Irish Stout). The water in Munich, Germany is also highly alkaline. In order to reduce the pH of the water, brewers often add more dark malt to brew dark beer such as Munich dark beer and German dark beer.
| Effects of brewing water components on beer flavor | |||
| Substances in water | Influence on beer flavor | ||
| Sulfate | Amplify the effect of hops, provide a crisp bitter taste, and make the finish drier | ||
| Chloride ion | Amplify the effect of malt, increase the sweetness of beer, and bring a full taste-just the opposite of the effect of sulfate! Therefore, brewers often change the emphasis of beer on dryness or fullness by adjusting the "sulfur-chlorine ratio" | ||
| Sodium ion | "Together with chloride ions, low concentrations can highlight the sweetness of beer and bring a full taste. However, too much sodium and chloride ions will make beer taste salty. | ||
| Magnesium ion | The malt already provides the magnesium needed by yeast, so there is no need to include magnesium ions in the brewing water. If the concentration of magnesium in the water is too high, it will bring a sour and bitter taste. | ||
| Calcium ion | Although calcium ions themselves have no effect on the final flavor of beer, they are a "necessity" for yeast. If the calcium ion content in the water is too low, the yeast may metabolize unpleasant flavors. The concentration of calcium ions and magnesium ions reflects the "hardness" of water. | ||
| Acidity and alkalinity | "The acidity and alkalinity of water (pH). If the pH is too low, it may have a sharp, dry and bitter taste; if it is too high, it may have a soapy and smooth taste and a metallic feel." Deeply roasted malt itself has a high acidity, which can reduce the pH of water. | ||
We have learned about the impact of the four major ingredients of beer on the flavor of beer, but this does not mean that piling up the "right" ingredients will definitely produce the corresponding flavor-beer fermentation requires complex chemical reactions. A good brewer can give full play to the advantages of the raw materials. On the contrary-equipment pollution, raw material ratio, yeast health, transportation and storage conditions, etc., if not controlled well, may lead to unpleasant tastes.
| Common off-flavors in beer and their common sources | ||
| Common odors | Common substances | Common causes |
| Green apple, grass | Acetaldehyde | Poor yeast health or too high fermentation temperature |
| Pungent alcohol, nail polish remover, burning sensation | Alcohol, fusel alcohol | Fermentation temperature is too high |
| Astringent taste | Tannins (polyphenols) | Saccharification water is too alkaline; hops are too much; over-washing of the lees |
| Butter | Diacetyl | Poor yeast health; fermentation temperature is too high; insufficient storage time |
| Wet cardboard, sherry, choking taste | Trans-2-nonenal | Oxidation (during brewing or storage) |
| Cooked corn, cooked vegetables (celery, radish, cabbage) | DMS (dimethyl sulfide) | Incomplete evaporation during wort boiling; Pilsner malt comes with it |
| Disinfectant | Chlorophenol | Excessive chlorine content in water |
| Skunk smell (sun odor), body odor | Mercaptan | Sunlight exposure |
| Sour (unpleasant), vinegar pungent, burning sensation | / | Wild bacteria/bacterial infection; acidic fruits, acidified malt or lactic acid bacteria |
| Rotten eggs, burnt matches | Hydrogen sulfide | Yeast autolysis; wild bacteria/bacterial infection |
| Bananas, pears, nail polish | Isoamyl acetate | High fermentation temperature; yeast characteristics |
| Moldy smell, cellar | TCA | Mold on brewing equipment or raw materials; mold infection |
| Metal, rust, copper | / | Rusty brewing equipment; high metal ion concentration in water |
| Rotten cheese, goats, smelly socks | Isovaleric acid | Aging hops |
The appearance of some odors is absolutely intolerable, while others are relative-a small amount in some wines is acceptable. The sensitivity to different odors (perception threshold) also varies from person to person.
