From the HBD Archive
From: (Desmond Mottram)
Subject: Re: low yield
Date: 1992-06-29 09:06:12 GMT

I missed Gordon's original post, so these details are snarfed from Jack's
reply. Gordon says:

> I posted here about 2 months ago complaining about low yield. The
> general concensus was to slow down my sparge, and that helped, but I am
> still not up to where I think I should be. Here are the details:
> 8 lb klages
> .5 lb munich
> .5 lb crystal
> I use a one step infusion mash at 155 for 45 minutes.
> The starting gravity is 1.036 and finishing is 1.006. With 9 lb
> of grain I think I should be getting around 1.040.

I'd expect to get still more than that. I mash in three gallons, sparge
with three gallons, and with 9lb of grain usually get around 5.5 gallons at
1042. Based on what the books say I would say I have room for yet further

I've also had problems with poor yield and was interested in the replies.
All I'd agree with:

Jason says check the pH. Dead right. The enzymes will slow unless you get
it right. Check what the correct figures should be because I'm going from
memory here, but I think you need to be between 5.0 and 5.5. Lower pH
favours one enzyme, alpha amylase I think. Higher pH favours the other.

Kinney says the temp is a mite too high. I agree, 155 is fine for starting
but you might do well to drop it to 150 after starch conversion, to assist
the beta amylase.

Then Kinney says 45 mins is not really long enough. I think he has put his
finger right on your problem here. I find 45 mins nowhere near enough when
mashes are being stubborn. The greatest amount of conversion happens early,
yes, but you need at least 30 mins more for dextrins to convert to maltose
and to wring the rest of the starch from the grains. On occasions when I've
reluctantly had to make do with poorly crushed grain, the mash has taken
over 4 hours. Dave Line even suggests mashing overnight! My next move in
your situation Gordon would be to double the mash time to 1.5 hours.
Furthermore, if your temp and pH are a bit off you will need more time

Lastly Kinney suggests a sparge bag. Yes again, I wouldn't be without mine.

Desmond Mottram.

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