What happens to beer when it is served using a party pump?

When beer is served using a party pump, it is exposed to oxygen, which can accelerate the spoilage process. The pump draws air into the keg, leading to oxidation. This oxidation can result in off-flavors and a decrease in freshness over time, making the beer spoil faster than if it were served using a traditional tap system.

Unlike other methods of serving beer, which usually keep it sealed and protect it from excessive oxygen exposure, the use of a party pump does not maintain a carbon dioxide environment. This means that while the beer may initially taste fine when first tapped, it will deteriorate in quality more quickly than beer served in a way that minimizes oxygen contact.