Attenuation issue

[drhookmec]

Well I'm open for ideas on this one.

I have a recipe I've been playing with and i can't get it to completely ferment out.
The recipe is simple..
30% 6-row
35% 2-row
35% flaked rice
protein rest at 120-122 1HR
sac. rest 148-152 2HRs
Mash out 160-168 10min

OG starts at 1040
I add 1min of oxygen using an oxygen injection system.
I pitch a 1.5L starter made 2 days earlier.
I normally use Wyeast 2000 Budvar.
Ferment for 14days at 53deg

FG finishes at only 1030

At this point it seams like i have tried everything.

So do any of you guys have some ideas that may get this beer to ferment out more??

tim

[timmomyces]

I believe several things could be contributing to your problem. You are under pitching your beer just ever so slightly i would recomend 3 liters of starter for a lager @ a SG of 1040 i would also omit using pure O2 to oxygenate your wort infact i wouldnt oxygenate my wort at all.

If possible, don't oxygenate your wort! The reason is that it is not the wort that needs the oxygen, it is the yeast. By oxgenating the wort instead of the yeast starter, it will cause an over production of cells due to the excessive oxygen presence. This then leads to the production of unwanted esters and higher alcohols that will compromise beer flavor.

When oxygenating starters, you cannot use pure O2... the reason is that the uptake occurs too fast and without a dissolved O2 meter ($$$), you cannot tell when to stop. The way to properly do this one is to aerate using a high pressure aquarium pump, sterile air filter and a stainless steel aeration stone, all of which are redily available. It is virtually impossible to over-aerate using air, so you will avoid oxygen toxicity problems that will occur if trying to do this with pure oxygen.

[slothrob]

I was wondering if the particularly long protein rest is the problem. Perhaps the beta amylase is denaturing during the hour long protein rest, I don't know the stability of the enzyme at 120°F. I would try skipping the protein rest, altogether.

Another thing to check is the calibration of your thermometer. It's possible you are mashing closer to 160°F than 150°F, which would result in a high FG.

[drhookmec]

Slothrob: I was thinking the same thing and going to try taking out the protein rest this weekend and see what happens.
The temp. gauges are spot on as i have checked them.
I'm using a 10gal Blichman boilermaker pot with a false bottom for a mash tun

timmomyces: I like the idea of omitting the oxygen injection cause as you know when dealing with lighter beers like this off flavors and smells are easily detected.
On the 3L starter is just shaking it up a little a good way of oxygenating it?
or should i invest in an aquarium pump?

Also what a bought maybe some amylase enzyme?
Anyone have any experience using this?

Thanks for the help guys..
I'll keep you posted.

tim

[slothrob]

Shaking is a surprisingly effective way to aerate beer, and will work pretty well for low gravity worts.

I suppose amylase would be an option, but it really shouldn't be necessary.

[drhookmec]

Well got this one figured out.
As timmomyces mentioned i was under pitching not just slightly but severely.

I also was not paying attention to the date on the yeast i was using.

Now with this beer I'm going with a 2L starter and using 2PKS of Bud Var
and having no problem getting her down to 1010.

Here are some calculators that have helped me and maybe they will help someone else.

http://www.mrmalty.com/calc/calc.html
http://www.yeastcalc.com

Tim

[slothrob]

Now with this beer I'm going with a 2L starter and using 2PKS of Bud Var
and having no problem getting her down to 1010.

Notice in that yeast calculator that you can use fewer packs with a larger starter and a much smaller starter by "intermittent shaking" of the starter. Also, a stir plate will allow an even smaller starter.

If you make more than one lager in a row, you can also harvest the yeast cake and use a portion of it for your next batch. For Lagers, I use about 1/3-1/2 of the harvested yeast in a full-sized batch or most of the yeast from a half-batch.

[C_R_J]

when i have had that problem, shaking, and overpitching, always has worked.

so shake that thing, and always pitch a tiny bit extra. itll drop out.