Homebrewing Process

Here, the brew kettle is lined with a mesh bag that will allow grains (malted barley, wheat) to steep in the kettle.

In the partial mash / ("brew in a bag") homebrewing process, there are rests at several temperatures to maximize conversion of starches in the grain to fermentable sugars. (Certain conversions are best in specific temperature ranges, where temperatures too low/high denature the naturally occurring enzymes that allow the conversions to take place).

Once the step mash is complete, the grain bag is removed and drained, and the remaining liquid (called "wort") is brought to a boil. In a partial mash process, some additional malt extract is added to increase the amount of fermentable sugars. The hops are added in the boil in the above-pictured muslin sack to reduce hop leaf material in the wort.

Hops are a cone-shaped flower - for brewing, they're often pelletized as shown in the packaging above. Depending on how long they spend in the boil, different properties are extracted. Hops added with 60 minutes remaining the boil are "bittering" hops - the hop oils will generally be converted to bitter tasting compounds; hops added with 20-30 minutes remaining are "flavor" hops; hops added at the end of the boil are "aroma" hops. André-Marie had hops added throughout the boil to extract a range of properties from the hops.

Once the boil is completed, the wort is chilled to get it to a temperature that is ideal for pitching the yeast. During the chilling process, the wort can continue to be stirred (creating a "whirlpool" to push sediment to the center of the kettle) and additional aroma hops can be added at this stage.

Here, a 5 gallon bucket is used as a fermentation vessel. The contents of the kettle are transferred to the bucket and additional water is added (as needed) to increase the volume to 5 gallons.

Liquid brewers' yeast for use in homebrewing comes in packets like shown above. Once the wort is at the proper temperature for pitching the yeast (around 65-80 degrees depending on the yeast strain (not too warm so the yeast cells do not die)), the yeast slurry is poured from the packed into the bucket.

Once the yeast is pitched, the 5 gallon bucket is sealed and put in a dark, moderate temperature location for a few weeks. The yeast cells will multiply and "eat" the fermentable sugars in the wort; their digestion byproducts are alcohol and carbon dioxide. As pictured above, the top of the fermentation bucket has an airlock to allow CO2 to escape. Once yeast activity slows and the yeast cells settle to the bottom of the bucket, the wort has become beer.

In preparation for bottling, the bottles are rinsed and sanitized. The beer (which is flat and uncarbonated at this stage) is mixed with a small amount of additional sugar. Once the beer is added to the bottles and the bottles are capped, trace amounts of yeast remaining in the beer will digest the newly-added sugar - however, unlike in the fermentation vessel where the CO2 escaped through the airlock, the bottle cap traps the CO2, resulting in the beer becoming carbonated. The bottling carbonation process takes a few weeks.

Now I need a beer!