Recipe Resizing - Hops Question

[Brundoggie]

When resizing a recipe from a 10-gallon batch to a 5-gallon batch, should I also halve the hop quantity? The recipe I'm looking at calls for frequent .5 oz Cascade hop additions and .25 oz just seems small to me.

Thanks!

 

[tally350z]

Most of the time the Hop Utilization is not as simple as dividing or multiplying it. Best thing to do would be to plug it into a program like beersmith and check.

 

[frozt]

Technically, Tinseth's hop util. equation only takes into account boil gravity and time. The IBU equation is just IBU = AAU * Util. * 75(Constant) / (Batch Size in Gallons), so I think scaling up should simply be multiplicative. For example, here are some of my numbers from a previous brew:

1 oz UK Kent Goldings (5.8% alpha) (30 min)
Boil Grav. = 1.090
Assuming 10% extra util. for pelletized hops

Util(30) = (1.65×(.000125^.090))×((1−(e^(−.04×30) ) )÷4.15)
= 0.123741 * 1.1 (pelletized) = 0.136115
AAU (Kent 30) = 1 oz * 5.8 alpha = 5.8 AAUs
IBU (Kent 30) = 5.8 AAUs * 0.136115 util * 75 / 5.0 gal. batch size = 11.842

So scaling *up* to 10 gallons should be as simple as doubling the hops in this case, or scaling by whatever factor applies.

Brundoggie, for curiosity's sake, can you post the recipe you're working with?

 

[iambeer]

Makes sense to simply cut the recipe by half. It's not like how much rocket fuel will get a smaller ship into orbit.

 

[Brundoggie]

Technically, Tinseth's hop util. equation only takes into account boil gravity and time. The IBU equation is just IBU = AAU * Util. * 75(Constant) / (Batch Size in Gallons), so I think scaling up should simply be multiplicative. For example, here are some of my numbers from a previous brew:

1 oz UK Kent Goldings (5.8% alpha) (30 min)
Boil Grav. = 1.090
Assuming 10% extra util. for pelletized hops

Util(30) = (1.65×(.000125^.090))×((1−(e^(−.04×30) ) )÷4.15)
= 0.123741 * 1.1 (pelletized) = 0.136115
AAU (Kent 30) = 1 oz * 5.8 alpha = 5.8 AAUs
IBU (Kent 30) = 5.8 AAUs * 0.136115 util * 75 / 5.0 gal. batch size = 11.842

So scaling *up* to 10 gallons should be as simple as doubling the hops in this case, or scaling by whatever factor applies.

Brundoggie, for curiosity's sake, can you post the recipe you're working with?

It's a Fire Rock Clone:

Recipe Type: All Grain
Yeast: Kolsch
Yeast Starter: Slurry
Batch Size (Gallons): 11.25
Original Gravity: 1.053
Final Gravity: 1.014
IBU: 35.2
Boiling Time (Minutes): 90
Color: 6.7
Primary Fermentation (# of Days & Temp): 14 at 68 degrees
Additional Fermentation: Cold conditioned for 10 days
Secondary Fermentation (# of Days & Temp): Straigh to keg
Recipe Specifications
--------------------------
Batch Size: 11.00 gal
Boil Size: 14.40 gal
Estimated OG: 1.053 SG
Estimated Color: 6.7 SRM
Estimated IBU: 35.2 IBU
Brewhouse Efficiency: 72.0 %
Boil Time: 90 Minutes
Ingredients:
------------
18.00 lb Pale Malt, Maris Otter (3.0 SRM)
2.00 lb Munich Malt (9.0 SRM)
1.00 lb Honey Malt (25.0 SRM)
0.50 lb Cara-Pils/Dextrine (2.0 SRM)

1.00 oz Centennial [9.50%] (60 min)
0.50 oz Cascade [7.80%] (40 min)
0.50 oz Cascade [7.80%] (30 min)
0.50 oz Cascade [7.80%] (20 min)
0.50 oz Cascade [7.80%] (10 min)
0.50 oz Mt Hood [3.70%] (5 min)

1 Pkgs German Ale/Kolsch (White Labs #WLP029) Yeast-Ale or Safale04 of WLP051
Dry hop with ½ Oz of Centennial per 5-gallons for 5-7 days.
Mashed at 154.

 

[Calder]

I agree, 0.25 ozs addition, is just too small.

I'd drop the 40 minute addition and keep the Cascade and Mt Hood additions at .5 ozs. This should keep the IBUs around the same and improve the hop flavor and aroma.

 

[Brundoggie]

I agree, 0.25 ozs addition, is just too small.

I'd drop the 40 minute addition and keep the Cascade and Mt Hood additions at .5 ozs. This should keep the IBUs around the same and improve the hop flavor and aroma.

Good idea, thanks!

 

[david_42]

I disagree. You are adding a full ounce of Cascade, just spreading it out in time. Each addition gives a specific bittering and oil extraction profle. If you are using a recipe for the first time, it makes sense to follow the recipe.

 

[Brundoggie]

OK, David 42 and Calder need to arm wrestle to determine who is right.

 

[Calder]

I disagree. You are adding a full ounce of Cascade, just spreading it out in time. Each addition gives a specific bittering and oil extraction profle. If you are using a recipe for the first time, it makes sense to follow the recipe.

Personally, I don't think the hop additions of the original recipe are not very good. But that is not the debate here. A 0.25 hop addition to a 5 gallon batch just seems to be senseless ... unless you are doing some continuous hopping.

The 40 minute addition adds no flavor or aroma, and not too much bittering. Upping the later hops and deleting this addition will give you about the same bittering, but also more hop flavor and aroma.

I'm suggesting he adds 1.5 ozs of Cascade, equally divided at 30, 20, and 10 minutes. He is going to get similar IBUs, with a little more flavor and aroma. To be honest, with only a half ounce addition of cascade at less than 15 minutes, I really don't think it is going to make too much difference.

I think he is starting off with a recipe with a poor hop schedule to begin with.