How to measure moisture content of hops

[fattymattybrewing]

If I have 500 lbs of hops which I need to dry, how do I verify that the moisture content is at 8 to 12 percent?

Is that % right anyway? I have heard 8-10%, 8-12% and 10-12%

I know there is no measuring or testing hardware or equipment you can buy to do this and I am dealing with hundreds of pounds.

I am not asking how how to dry and how to harvest. I just am looking for a way to check for moisture content. Break out your scales...

 

[GilaMinumBeer]

Break out your scales...

Yes ^^^^^^. Interesting reading?

 

[fattymattybrewing]

Very Nice, keep the ideas comin'!

 

[GilaMinumBeer]

There are meters for agricultural use but they are pricey. Might not be worth it if this 500 is a one time thing.

 

[fattymattybrewing]

There are meters for agricultural use but they are pricey. Might not be worth it if this 500 is a one time thing.

Can you tell me if you have any sources or resources of where I can find a selection of meters for testing this?

I have heard there are no meters which can truly measure MC in hop cones.

 

[GilaMinumBeer]

I just googled moisture meters and got hits for agricultural purposes.

 

[fattymattybrewing]

This looks like it might work but I wonder at what cost?
http://moist-vu.com/

 

[fattymattybrewing]

I also found a super cool article with moisture content specs in the Sept/Oct issue of GVH's newsletter > under the heading > drying hops.

http://www.gorstvalleyhops.com/uploads/September_newsletter.pdf

 

[GilaMinumBeer]

This looks like it might work but I wonder at what cost?
http://moist-vu.com/

If you have to ask, you can't.....

Sorry, the name alone looks like it belongs on the health and hygiene aisle.


You know, next to the contacts......

 

[GVH_Dan]

I also found a super cool article with moisture content specs in the Sept/Oct issue of GVH's newsletter > under the heading > drying hops.

http://www.gorstvalleyhops.com/uploads/September_newsletter.pdf

Yep, that's the only reliable way to do it that I have found. Take two samples of equal weight and volume. One you dry until all the moisture is gone. The other you put in a bag that will allow air to pass through and put it in the oast. That sample is removed periodically for weighing purposes.

The fancy way of doing that is to get a specialized chamber that includes a scale. You place the sample in and it weighs the sample. It then drives out the moisture until the sample no longer changes weight. It can then give you the dry weight and moisture content. We just picked one up and they aren't cheap.

There are various moisture meters available that look at the electrical impedance through your sample. They work really well on drywall, wood and other solid surfaces. They also work well with dense product like corn, wheat, baled hay...and baled hops. They don't work so well with loose hops because there isn't necessarily a continuous electrical connection. so therefore you don't know your moisture content until it is all baled up, which is too late.

Yes, they also come with cup samplers. Its a cup that you shove the sample in to measure. I've tried a few out. I could get from it the general direction and rate of moisture removal but not the actual moisture content.

The problem with these devices is they need to be calibrated for the product and the temperature. Using a device calibrated for corn will not work for hops. Using a device calibrated at 80F, will not work on hops at 30F or 120F.

If you are really interested, Samual Jackson www.samjackson.com seemed to have equipment that was calibrated for baled hops. That's about the best I could find.

 

[GVH_Dan]

By the way, for the home grower its difficult to get an accurate moisture content. You would end up using your entire harvest just to get the accurate number.

The better way is to watch the cone. I found at about 20% moisture content the cone starts to open just a bit. When all the moisture is gone the cone is really open and the bracts (leaves) are starting to fall off. This is too dry. Shoot for something in the middle. Maybe this season I'll try to grab some pictures of the cones at different MC's.

 

[fattymattybrewing]

By the way, for the home grower its difficult to get an accurate moisture content. You would end up using your entire harvest just to get the accurate number.

The better way is to watch the cone. I found at about 20% moisture content the cone starts to open just a bit. When all the moisture is gone the cone is really open and the bracts (leaves) are starting to fall off. This is too dry. Shoot for something in the middle. Maybe this season I'll try to grab some pictures of the cones at different MC's.

Dan

I was waiting for your response on this topic. I kind of figured you are in the man who can make the most sense out of this and be able to still communicate the info back out.

Please do plan on taking photos of the different MC stages with documented percentages for each pic.

Any other thoughts for figuring MC for the layman would be just peachy!

 

[Cliff897]

Can you freeze them as is?

 

[Randar]

By the way, for the home grower its difficult to get an accurate moisture content. You would end up using your entire harvest just to get the accurate number.

The better way is to watch the cone. I found at about 20% moisture content the cone starts to open just a bit. When all the moisture is gone the cone is really open and the bracts (leaves) are starting to fall off. This is too dry. Shoot for something in the middle. Maybe this season I'll try to grab some pictures of the cones at different MC's.

If you can take some good detailed pictures with descriptions of the feel and behavior I think that would be terrific.

From what I have read, the ideal MC for dried hops is when the internal stem starts to become brittle but before the leaves are totally paper-dry and falling off.

And freshops has a better and more accurate description of it than I:

http://www.freshops.com/hop-growing/hop-gardening/#drying

 

[GVH_Dan]

Sure...just use them within the 3 months. Even frozen, they will oxidize/degrade and the more moisture in them the faster it will occur.

 

[fattymattybrewing]

Can you freeze them as is?

You can freeze them wet (not dried) but if you are planning on pelletizing or storing for any length of time (more than 2 months) they need to be dried to the correct moisture content.

 

[Randar]

Sure...just use them within the 3 months. Even frozen, they will oxidize/degrade and the more moisture in them the faster it will occur.

And of course using them "wet", even after thawing, you will have a hard time reproducing batches since the extra weight and variant MC will mess with your recipes, even if you have "rules of thumb" for conversion.

 

[Cliff897]

One way I know is Vacuum

500 pounds is a lot you gotta put 'em in a vacuum chamber and pull till all the water has transpired out of the cells.
You need an industrial app vacuum pump preferably a twin stage rotary vain type and a large vacuum reservoir with water extraction and of course a large chamber for the hops.


I don't see a way through to scaling up a DIY app in any time frame.

You might try calling some food processing houses and asking if they have the equipment. For a fee you can get it done


The old witch of the swamp would just string them up and hope for the best.

I'd try food service processors.
http://www.vacuum-pack.com/
http://www.dougcare.com/

Google the exact phrase:
vacuum packing companies

The people who Make the equipment will be more than happy to refer you to one of their customers.

It will help grease the wheels if you come off like a small scale business instead of just a guy with a lot of hops. Less liability issues for the referral.

 

[Bensiff]

Watch what the commercial folks do, they have a handheld probe they stick into the bale that gives a quick read. If that is accurate enough for them it should be good enough for you too. However, that may be a last quality control deal before it goes out the door...I would need to drive over to Yakima and tour HopUnion to really see.

 

[GVH_Dan]

And of course using them "wet", even after thawing, you will have a hard time reproducing batches since the extra weight and variant MC will mess with your recipes, even if you have "rules of thumb" for conversion.

Right, when they come off the bine they are 60 to 80% moisture content, usually towards the 80%. That means if you had 1 lb of wet hops at 80%, you would have .22 lbs of hops if they were dried down to 10% MC.

 

[GVH_Dan]

Watch what the commercial folks do, they have a handheld probe they stick into the bale that gives a quick read. If that is accurate enough for them it should be good enough for you too. However, that may be a last quality control deal before it goes out the door...I would need to drive over to Yakima and tour HopUnion to really see.

Those were the sensors I was mentioning. They really only work once the hops are baled. Before that, the hops are too loose. So it doesn't help during the drying process. It is, as you said, a QC check to make sure they are dry enough to not compost and start a fire.

 

[Randar]

Right, when they come off the bine they are 60 to 80% moisture content, usually towards the 80%. That means if you had 1 lb of wet hops at 80%, you would have .22 lbs of hops if they were dried down to 10% MC.

Excellent tips. Any guidance for visual/hand estimation of original moisture content? i.e. any observations I should be looking for to ballpark it as my weight-based starting point?

 

[GVH_Dan]

There's no real way to tell a 60% from a 80% moisture content just by looking at it. If you have a super-accurate scale and are willing to sacrifice a couple of cones, you could figure it out.

 

[HoppyDaze]

WAG it...

Wild
Ass
Guess

 

[Randar]

If you have a super-accurate scale and are willing to sacrifice a couple of cones, you could figure it out.

Do tell! ^^

 

[GVH_Dan]

I also found a super cool article with moisture content specs in the Sept/Oct issue of GVH's newsletter > under the heading > drying hops.

http://www.gorstvalleyhops.com/uploads/September_newsletter.pdf

Basically follow the method I described in the above newsletter article.

The basic equation is:
M% = ((Ww ‐ Wd)/ Ww) x 100
M% = moisture content(%)
Ww = wet weight of the sample
Wd = weight of the sample after drying

If you want to know the moisture content, take a small sample and weigh it to get Ww. Then get the moisture out. Either bake it or put it in a microwave with some desiccant material to pull out the moisture. When you are sure it is completely dry, that is your Wd. Now plug it in to see your starting moisture content.

I wouldn't use that sample in your beer, though. Especially if you used the microwave because most desiccants aren't food grade.

The trick is that if you use a really small sample, you need a very accurate scale. For our purposes, we start with about 100 grams, which is about 1/3 of a gallon of hops. The final drying weight is around 21 to 22 grams. Start with 1 gram and you are trying to tell the difference between .21 and .22 grams. That's why it has to be a very accurate scale.

 

[eformo]

i realize the last post was from 2010, but this is a great way to tell when you are near the 21% dry matter mark: https://www.uvm.edu/extension/agriculture/engineering/?Page=hopscalc.html which is part of this article: http://www.uvm.edu/extension/cropsoil/wp-content/uploads/Hop_harvest_fact_sheet.pdf
I only have 26 plants so didn't do the amounts they said, this is what i did:
1. picked 100g from my 8 centennial plants
2. put a bowl on scale and tare
3. put hops in bowl, weigh, mark down
4. microwave for 1 minute
5. stir
6. weigh
7. microwave for 1 minute, stir, weigh
8. repeat until the weight does not drop anymore which means you are at 0% moisture content