As an expert sommelier and brewer, I can assure you that the freshness of keg beer can vary depending on several factors such as whether the beer is pasteurized or non-pasteurized, the dispensing method used, and the temperature and pressure at which the keg is stored.
Let's start with non-pasteurized draft beer. This type of beer is not heat-treated to kill bacteria and yeast, which means it is more perishable than its pasteurized counterparts. When stored properly in a keg with the right temperature and pressure, non-pasteurized draft beer can remain fresh for about 45-60 days. This is because the absence of pasteurization allows for natural fermentation to continue in the keg, which can affect the flavor and stability of the beer over time.
On the other hand, pasteurized draft beer undergoes a heat treatment process to kill off any potential microorganisms that could spoil the beer. This extends its shelf life and allows it to maintain its freshness for a longer period. When stored and dispensed correctly, pasteurized draft beer can last for about 90-120 days in a keg. The heat treatment helps to stabilize the beer and preserve its quality, making it less prone to spoilage.
Now, let's discuss the importance of proper dispensing methods. When using a CO2 system to dispense keg beer, it is crucial to maintain the appropriate temperature and pressure. The temperature should be kept between 36-40 degrees Fahrenheit (2-4 degrees Celsius) to prevent the beer from spoiling or becoming flat. The pressure should be set according to the style of beer being dispensed, typically ranging from 10-14 PSI. By ensuring the correct temperature and pressure, the beer will remain fresh for the mentioned durations.
However, it's worth noting that if you're using a party pump, also known as a hand pump or air pump, to dispense keg beer, the freshness lifespan is significantly reduced. With a party pump, the beer is exposed to air, which accelerates the oxidation process and promotes the growth of spoilage-inducing microorganisms. In this case, the beer will only remain fresh for a short period, typically no more than 8-12 hours. Therefore, it is essential to consume the beer promptly when using a party pump.
The freshness of keg beer without being tapped can vary depending on whether it is pasteurized or non-pasteurized, the dispensing method used, and the storage conditions. For non-pasteurized draft beer, you can expect it to last around 45-60 days, while pasteurized draft beer can last for about 90-120 days. It's crucial to use a CO2 system for dispensing and to maintain the proper temperature and pressure to ensure the beer remains fresh throughout its lifespan.