How to Control Beer Oxidation During Homebrewing?
The subject of the introduction of oxygen to wort and yeast during brewing process has attracted a lot of equal measure of debate over the last couple of years. This subject has attracted a lot of research and analysis. Due to the complex nature of beer chemistry, the components that contribute to staling flavor cannot readily be determined. Using the proper brewing techniques and controlling the amount of oxygen to be contained in a beer during a brewing process, goes to a great extend to determining the flavor of beer. We are humans with the ability to control a lot of things. Just like the way you would want to control your life and have a lot of fun – be it on a night out on an exquisite limo service or a weekend out playing your favorite sport, equally – Brewers need to control oxidation levels during a beer brewing process.
Aeration is good, but oxidation is bad.
Yeast is the most significant and contributing factor in determining the quality of fermentation. However, oxygen can be the most important factor in determining the quality of the yeast. This means that oxygen serves as both your friend and enemy and it is important to understand when to strike a balance.
You should not allow air when the wort is warm or even hot. Aerating a hot wort will cause the oxygen to chemically the various wort compounds. With time, these compounds break down to free atomic oxygen back into the beer where it can oxidize the alcohols and any hot compounds to produce non-desired aromas.
Oxidation of your wort can happen in several ways – First, through splashing or aerating the wort when it is hot, and second pouring the hot wort after the boil into cold water in the fermenter to cool it – and then add oxygen to the yeast. You have to be careful to ensure that the wort is not hot enough to oxidize the wort when it picks up oxygen from the splashing. To prevent oxidation, cool the wort rapidly to temperatures below 80-degree F and then aerate the wort to provide the dissolved oxygen that the yeast needs.
Oxygen is introduced after the primary fermentation has started. At this stage, it may cause the yeast to produce an initial fermentation by-products such as diacetyl. Some strains of yeast may respond well to open fermentation process without necessarily producing off-flavors. However, even in those strains, exposure to oxygen after fermentation may lead to staling your beer.
To achieve the optimal results regarding balancing aeration and oxidation levels, pitch a sufficient amount of healthy yeast – probably one grown in a starter that matches your intended fermentation conditions. Ensure that you cool the wort to fermentation temperature and then aerate the wort to provide the oxygen that the yeast needs to grow and reproduce. Once the fermentation is complete, protect the beer from oxygen to avoid oxidation and staling.
Bottled beers may not help but become oxidized over time. Know that some beer styles may be impacted greater than others. As a home brewer, you may use oxygen absorbing bottle caps that can help mitigate oxidation.