Please help: Bitter wort?

I am currently making a recipe from Radical Brewing. After a two hour mash (mostly at 151-153, but started high, between 156-158 for first 15 minutes), I tasted the wort and it was actually bitter. I did a starch conversion test with iodophor, and it wasn't done converting. Worried that most enzymes wouldn't have survived after 2 hours of mashing, I had 1.5 lbs of 6-row domestic that I added, hoping it would help with starch conversion. I'm waiting 30 minutes now. Does anyone have any idea why wort would taste bitter? There's no hops or herbs in it. I listed the malts in the wort:

13 lbs biscuit malt
6 lbs pale ale malt
6.5 gallons water

I should also add that I used ph 5.2 buffer in the mash.

Whoa, that's a radical recipe alright.

Most sources suggest 15% biscuit malt max. 65% Biscuit malt seems radical and, to me at least, a bit crazy.

I suspect there's nowhere near enough enzymes in 6lbs of pale ale malt to convert all the starch. Heck, it probably wouldn't even be enough with regular 2 row, let alone pale ale malt which has lower enzymatic power. If it was going to work, a protein rest might have helped, too.

That bitterness I suspect is the toastiness/biscuitness to an extreme level.

Radical is sometimes genius, sometimes crazy, but you've gotta try it it to figure which it is I guess. I give you props for trying it out.

Yeah, looks like the malt quantities are reversed, but that would still be very high.
You know, with that much biscuit flavor, you could toss in some country ham and cheese..... :cross:

bull8042 said:

Yeah, looks like the malt quantities are reversed, but that would still be very high.
You know, with that much biscuit flavor, you could toss in some country ham and cheese..... :cross:

Click to expand...

Yeah I'm not sure. It's definitely the quantities that the book gives, but of course there could have been a mistake.