Funny after taste

Hi, I have just tried my first homebrew ( coopers Mexican larger), it's fizzy, has a good colour but a funny after taste. It tastes a little soapy, any ideas why???

From John Palmer:

"Soapy flavors can caused by not washing your glass very well, but they can also be produced by the fermentation conditions. If you leave the beer in the primary fermentor for a relatively long period of time after primary fermentation is over ("long" depends on the style and other fermentation factors), soapy flavors can result from the breakdown of fatty acids in the trub. Soap is, by definition, the salt of a fatty acid; so you are literally tasting soap."

Here is a link to some good info on what causes different off flavors:

http://www.howtobrew.com/section4/chapter21-2.html

Soapy flavor can be thought of as sour. Is it spicy? I ask these questions because I think that you have an infection sue to acetic acid or phenols. Many brews ago I was having problems with all my beers with low lovibond having a "soapy" flavor. This was very frustrating. It turned out that I had one piece of equipment that I was not cleaning properly.

First be sure that you are cleaning all your equipment thoroughly, in my case it was a bottle filler that, at the time, I was unaware you could take apart and clean. Once I replaced the filler, the "soapy" flavor has never returned.

Second, if you want more input posting some brew notes/processes will be helpful.

But for now keep it clean.