Percent yield and procedure

[Nightforce]

Well I've delved more into grains, actually calculating yields and whatnot. Before I didn't care much about yields, grain bills etc.

So this last mash I boiled 8 gallons of water, then added 10# of cracked corn, stirring occasionally so it would not burn and boiled/simmered that for 40 minutes. It seemed rather thick, so I added another gallon of water to thin it out and make up some of the water lost during boiling. I covered it and when the temp got to about 180°F I stirred in 2# of malted barley and let it sit. Once the temp got to about 165°F I stirred in a tablespoon of alpha-amylase and let it sit, stirring occasionally, until the temperature got to 145°F then added a tablespoon of gluco-amylase. This morning the temperature was 110°F in the covered kettle. I pulled off some of the top clearer portion and cooled it to 60°F; the sp. gr. was 1.032. Quite a bit low at only about 4% potential abv. Using a total of 12# of grain in 9 gallons of water is about middle of the 1-1.5# grain per gallon of water.

If I did my math right (check me please)

2# 6-row in 9 gallons = 7.8 ppg
10# corn in 9 gallons = 43.3 ppg
total of 51.1ppg theoretical (43.4 at 85% typical)

32/51.1 = .626 or 62.6% yield, FAR from the theoretical and only 73.7% of typical yield.

Have I done my math right and does anyone have suggestions as to why my yields would be low.

Thanks.

[Dnderhead]

no,your mash looks ok as far as i can see,it takes about 2x as much grain as sugar.
1 lb sugar per.gal. =7% ,,,,2 lb grain per. gal.= 6%

[ArkyJ]

Ah??? isn't the malted barley supose to go in at a temp of 150 to 155 degrees? Not 180.
Just asking.
ArkyJ

[rad14701]

Ah??? isn't the malted barley supose to go in at a temp of 150 to 155 degrees? Not 180.
Just asking.
ArkyJ

Under 165F, maximum, if you don't want to kill the enzymes as I recall...

[Nightforce]

Next batch I'll wait until the corn is 165 or less an add both the alpha-amylase and the barley. I'll also keep the amount of water down to get the sp. gr. up too.

This last batch I just added 5# cane sugar.

I also pitched a yeast starter this morning while the mash was at about 105F. WOW, a yeast starter and high temps really kicks things off. 2 hours after I'd pitched it you could see CO2 bubbles coming up and when I checked it lunchtime, about 4 hours later, it had formed a small cap and was bubbling away. This ferment should go quick.

[Nightforce]

Second attempt.

Boiled 10# of corn in 8 gallons of water, waited until 165°F and added baking soda to bring the pH up for the enzyme, added 2# malted barley (2-row) and alpha-amylase. Waited a little longer than an hour until the temps dropped to 145°F and added citric acid to bring the pH to around 4 for the gluco-amylase, added that and mixed real good. This morning I pulled off 500ml of the clear liquid on top and cooled to 60°F and tested. I got 1.042.

I'm pretty sure that at least a gallon has boiled off so do I use the original water content or the final boiled off amount. Seems like it should be the volume as tested not starting.

[islandgreen1971]

Actually Malted Barley is @ 148° and lower and working til around °110.

[woodshed]

Actually Malted Barley is @ 148° and lower and working til around °110.

This statement hints at the truth but is not completely accurate.

Malted Barley will convert at the temp rad listed and down from there.
The different enzymes inherent in barley work at different temps.
A more accurate statement is that the enzymes you want to do the work operate within that temp range.
Unless your going for some un fermentable sugars as well.

[woodshed]

Yeah but even an old thread deserves a trip down memory lane. Might get revived and teach someone a thing or two.

[Kelbor]

I may be wrong in this but three years ago (ha!) the OP should have mixed up his mash before straining a sample to obtain the S.G. - I've always mashed in my barley at 150 as well.