What does too much unmalted wheat do to beer?

[Fir Ken]

I brewed a hefeweizen that called for 5 lbs of wheat malt. After mashing for 90 minutes I had very low efficiency. after fermentation the beer had a cardboard taste to it. I initially though of hot side aeration due to a stuck sparge that took some work to free. I now am wondering if I was given unmalted wheat instead of malted wheat which I believe would cause the low effeciency, but would that cause a cardboard taste as well?

Thanks, Ken

[dmtaylor]

Unmalted wheat can still convert just fine as long as you had enough other malts in the mash to convert it. What was in the other half of your grist?

If you really didn't have enough enzymes in your mash, then perhaps you are tasting unconverted starch. Otherwise, oxidation would cause cardboardy flavors. This could come from too much oxygenation, not a long enough boil, things like that. Not very likely, but possible.

[mobrewer]

If the cardboard taste it would be due to oxygen exposure post fermentation. Hot side aeration isn't a concern.

[BDawg]

High levels of proteins can form lipids which are the basis of soap and hence soapy off flavors.
At low levels (of the lipids), I can see that tasting a little off and kind of cardboardy.

[troybinso]

High levels of proteins can form lipids which are the basis of soap and hence soapy off flavors.
At low levels (of the lipids), I can see that tasting a little off and kind of cardboardy.

The cardboard off-flavor probably comes from the most likely source - post fermentation oxygen like mobrewer said.

There is no reason that using wheat: malted, unmalted, flaked, torrified as a part of your recipe would cause oxidation off-flavors.