Malting and mashing are essential parts of the beer making process. These steps influence quality, flavor, and character of the final beverage. They transform the raw grain to a sugary wort in preparation for fermenting.
Malting
Malting is the initial stage in the brewing process, in which grains are prepared for fermentation. The popular grain for malting is barley. Wheat, rye, and oats are also used.
The malting process consists of three primary steps: steeping, germination, and kilning. Active enzymes include alpha amylase, producing glucose, and beta amylase, making maltose or malt sugar, maltotriose and maltodextrins.
During germination and sprouting, the enzymes facilitate transition of grain seed to seedling, breaking down cell walls and creating sugars from starch.
The malt producer halts this phase when enzymes reach optimal levels.
For storage the grain is dried by air circulation at a temperature of about 50°C. Overheating kills seeds and they won't germinate. After drying, the the product is cleaned and can be stored for up to 18 months.
Wet Stand (Steeping)
Mashing begins with steeping or wet stand. Barley grains are soaked in hot water for several hours.
This process increases the moisture content of the grains, activating enzymes like amylase by triggering germination. Steeping temperatures are between 65.5°C (150°F) - 76.7 °C (170°F).
During steeping, grains absorb water and swell, preparing them for the next phase. Grain moisture content increases from around 12% to between 40 and 45%. Steeping procedure affects quality of the malt.
Germination
When the seed starts to germinate, amylase breaks down starches in the kernel to make sugars like glucose and maltose, to nourish the seedling in early growth. The mix may be aerated by injecting bubbles.
After steeping, the grains are encouraged to germinate in a controlled environment for several days. The purpose of germination is to cultivate barley sprouts and enable formation of malt enzyme beta amylase.
The enzymes alter the barley endosperm's structure by degrading the cell walls and protein matrix. Germination generates significant heat, and without control the malt can catch fire.
Germination requires careful monitoring of temperature, humidity and airflow so the grains develop evenly. After a few days, the germinated grains are known as green malt.
Kilning
The final step in malting is kilning, where the green malt is dried in a specialized oven or kiln. This process kills the seedlings and halts germination. It retains enzymatic activity and infuses flavor and color.
As the grain dries, the temperature of incoming air can be increased for the second phase of forced drying. The goal for malt moisture after kilning is about 5% by weight.
In forced drying, the relative humidity of the air exiting the bed decreases, allowing the maltster to recycle some of the warm air as return air. In the final hours of kilning, the air temperature is increased to over 80°C.
In this curing stage, heat converts S-Methylmethionine (SMM), a compound in barley, into dimethyl sulfide (DMS), lowering the malt's DMS potential. Dimethyl sulfide is an off flavor and also a sign of bacterial contamination.
Malts lightly kilned, like pilsner or lager malts, retain much of the SMM content. In contrast, in higher kilned malts, such as pale ale malt, a larger amount of SMM is converted to DMS.
Darker kilned malts contain almost no SMM. Most is turned into DMS. The high temperatures of kilning also produce the color in malt through the Maillard reaction, a process of browning and flavor development.
The malt cools before the kiln is emptied (stripped). Temperature and time during kilning can be adjusted to produce different types of malt. Each imparts unique flavors and colors to the final beverage.
The Mashing Process
After malting comes mashing. Malted grains are combined with hot water to extract fermentable sugars. This process enables the enzymes in the malt, mainly α-amylase and β-amylase, to convert starch into sugars.
Mashing happens in several stages.
Mixing
In the first stage of mashing, the crushed malted grains are mixed with hot water in a mash tun, a large vessel. Temperature of the water is between 60°C to 71°C (140°F and 160°F).
This activates the enzymes in the malt. Mixing ensures the water permeates the grains evenly, for optimal extraction of flavors and sugars.
Saccharification
Once the mixture reaches the desired temperature, the mashing process enters the saccharification stage, where enzymes break down complex sugars into simpler fermentable sugars. This process takes about an hour.
This is the main work of the two key amylase variants: alpha-amylase and beta-amylase. Each enzyme has a specific role, reducing starches into sugars ultimately consumed by yeast during fermentation.
Lautering
After the saccharification process is complete, the mixture enters lauter phase. Here, the wort is separated from solid grain husks.
This is usually done by draining the wort and rinsing it with more hot water, or sparging. Lautering extracts as much sugar as possible, gives clarity to the final wort and enhances brew quality.
Boiling
Once the wort is extracted, it's boiled. Hops may be added for flavoring and preservation. The boiling stage sterilizes the wort and further develops the flavors derived from the malt and hops. Boiling takes 60-90 minutes.
In step infusion and decoction mashing, the mash is heated to different temperatures to allow specific enzymes to work optimally. Similar processes are used in large scale and homestead brewing.
Temp °C | Temp °F | Enzyme | Breaks down |
40–45 °C | 104.0–113.0 °F | β-Glucanase | β-Glucan |
50–54 °C | 122.0–129.2 °F | Protease | Protein |
62–67 °C | 143.6–152.6 °F | β-Amylase | Starch |
71–72 °C | 159.8–161.6 °F | α-Amylase | Starch |
Importance of Malting and Mashing
Malting and mashing define the character of the beverage, just like every step in the beer making process. Choice of grains, the specific malt types utilized, and techniques used contribute to aroma, taste and texture.
Variations in malting influence the beer’s sweetness, bitterness, color, and body. Brewers can craft unique and diverse beverages by monitoring and adjusting the malting and mashing processes.
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