Fermentation under Pressure Easy Guide

This is one area homebrewers tend to neglect when they first being with homebrewing. Importance of yeast and fermentation. Many start by simply fermenting yeast at room temperatures and many find that this presents a less than satisfactory result.

They then seek a way to improve this. Typically without spending a lot more money. Until they either invest in full temperature control or go get the pressure fermentation chamber.

For more tips on successful fermentation check our Homebrewing techniques on specific gravity.

A pressure meter connected to a fermentation vessel.
Credit:https://www.buttcrackbrewery.com/kegco-brite-tank-diy-spunding-valve-and-fermenting-under-pressure/

The difference between lager and ale yeast fermentation under pressure

For the vast majority of homebrewers, the main issue is having too higher a temperature for fermentation. Especially when it comes to lager fermentation. Pressure fermentation doesn’t need precise temperature control to work and works very well to help prevent off-flavors linked to fermentations that are too hot. Ever since the 1960s commercial brewers started using pressurized fermentation as a tactic to produce very clean fermentation results.

Whilst fermenting hot and this speeding up the time that it takes yeast to complete its job. This was vastly just used in producing lager, as those fermentations took longer when compared to ale. In the 1980s more experimentation was done with ale yeast under pressure. And the results didn’t go as well as expected. the main beer types that benefit from fermentation under pressure are lagers and hoppy beers.

Converting a keg into a fermentation under pressure vessel.
Credit: https://beermaverick.com/guide-to-fermenting-homebrew-in-a-corny-keg/

Positives & Negatives

You can ferment at warmer temperatures without the usual off-flavors. This is because you are fermenting hotter full attenuation has a better chance of being reached and also being reached faster. Because your fermentation headspace is full of CO2 you have the removal of oxygen making your beer last longer. Another great benefit is that the oxygen in your vessel is used to naturally carbonate as your fermentation is in progress. Due to your vessel not blowing off as often you’re keeping the aroma of your beer much more than a fermentation using an airlock.

Negatives only apply if you have too much pressure. It can have an adverse effect on your yeast and its health will decline. This will greatly reduce yeast growth and viability.

It is vital to realize that different types of yeast handle pressure differently. When it comes to lager yeast pressure is usually done right from the start of fermentation. Wht ale yeast we usually want esters as they provide the yeasts characteristical flavors. By adding pressure we will restrict cell growth and thus ester production which then has an effect on the overall flavor. Commonly with malt of ale styles, the majority of the fermentation will be done usually without pressure. The as it is closing in on the final gravity point pressure is added.

this will help complete the process faster and start carbonation in a unit tank. If you plan dry-hopping the beer then you can easily just remove the pressure, add your dry hops and then repressurize. Dry hopping under pressure is a great way to go because the aroma is kept within the vessel.

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