Off flavors...?

[rsmillie76]

Recently brewed a rye IPA. Tasted it along the way (post primary, post secondary). All seemed well...then I kegged it. I set it at the proper psi and left it alone for two weeks. Then I tried it! It went from being bright and crisp to having a soapy aftertaste with none of the hoppy/rye brightness that was there just a few weeks ago. I sanitized the corny and cleaned the lines before kegging. Anyone have any ideas?

 

[Nanobru]

Besides a poorly rinsed keg, possibly "soapy" mistaken for "cardboard"?, which would indicate oxygenation. soapy is a pretty unfamiliar naturally occurring off flavor. Ive had bad tasting co2 before as well. Take a whiff straight from the hose to rule that out.