low o.g. with unmalted wheat

[thelastdandy]

i've been trying to find an answer to this and can't figure it out. so, i used to purchase all of my grain from brewmasters warehouse because i was getting great efficiency with their crush. since they are no longer in business i recently went to northern brewer. i brewed a wit last weekend which was heavy in unmalted wheat and some flaked oats. i missed my o.g. by ten points. i was wondering if using so much unmalted wheat would have given me poor mash conversion (iodine test seemed ok) or if anyone else has noticed an efficiency drop using northern brewers crushed grains. i mashed for 60 min at 152 and fly sparged. i don't mash out, but my sparge water cooled down and never got the temp on the grain bed past about 155.

i plan on brewing a westvletern 12 clone this weekend (which is fairly expensive after buying all of the candy syrup and what not) and really don't want to miss my target gravity on this one.

if anyone has any suggestions that might help me pinpoint this it might help me sleep better tonight

 

[doug293cz]

If the crush you are getting now is coarser than what you used previously, you may need to mash longer, since larger grits take longer to convert than smaller grits (I can give a long winded explanation if you ask.)

Also, the iodine test is pretty unreliable. Many people recommend making sure you have no grain bits in the test sample, but that's crazy because the unconverted starch is in those grain bits, not in the liquid. It's all about the kinetics of conversion (again a longer winded explanation is a request away.) A better way to monitor degree of conversion is to measure the SG of the wort in the mash using the technique described here: http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency#Measuring_conversion_efficiency.

Edit: Another possibility is that due to the unmalted wheat, you didn't have enough diastatic power (available amylase enzymes) to complete conversion. What was your grain bill?

Brew on

 

[thelastdandy]

i was kinda thinkin about the diastatic power as well. grain bill was upwards of 25% unmalted wheat and about 3% flaked oats. has anyone else noticed a drop in efficiency with northern brewers crush?

 

[thelastdandy]

great link too. thanks.

 

[BrewerBrad82]

I get my ingredients from Northern and I always hit about ~80% mash efficiency. Did you brew the Hoegaarden clone? I recently did it and since there is so much unmalted wheat in there, I mashed for 90 mins. Because of the large percentage of non-diastatic grist in the grain bill, it will take longer for the enzymes in the malted stuff to convert all the available starches into sugars. I came in a few points high compared to the stated OG on the instructions, I am guessing that the instructions are written to target 70% efficiency or so. Ive never experienced too coarse of a crush from NB, happy camper here.

 

[doug293cz]

i was kinda thinkin about the diastatic power as well. grain bill was upwards of 25% unmalted wheat and about 3% flaked oats. has anyone else noticed a drop in efficiency with northern brewers crush?

If you had at least 50% normal 2-row (or other base malt with high diastatic power), that should have been enough to convert that much wheat and oats, although as @BrewerBrad82 said, it might require more mash time.

Brew on