Drying hops in sunlight, a discussion.

[COLObrewer]

OK fellow brewers,
I've had numerous discussions with brewers and hop growers and nobody seems to have an answer for me. The question simply is: Why can we not dry hops in the sun?

I've heard of reasons such as: It will skunk the hops. How and why would this happen?

Also, It increases the rate of oxidation. What does this do? Why would it not be oxidized with any type of drying?

Can you time the sun session to lessen the problem(s)?

All I have are questions, point me to some data.

 

[cheezydemon3]

After 1000's of years of not drying them in the sun......WITH ALL DUE RESPECT.....I doubt you will be the first to try.

There is a reason no one does it.

Go ahead! Give us some data.

 

[ptra1004]

I have found that the hops lose some of their pungency. There is probably a chemical equation that explains the process by which sunlight would cause the alpha acids to breakdown, I don't have it though... I have been blessed with a room in the house that gets ridiculously warm in the late summer/early fall and have just continued to dry out my hops there on an improvised rack made of 2x's and window screens. Works well for me.

Sorry, that isn't data, Just personal experience...

 

[COLObrewer]

After 1000's of years of not drying them in the sun......WITH ALL DUE RESPECT.....I doubt you will be the first to try.

There is a reason no one does it.

Go ahead! Give us some data.

Yea, but I wanted you to do it

Seriously, as you've said, somebody has had to try it with serious testing for different times in the sun? Or is it simply because of uncontrollable weather? You could do it in greenhouses, but it would be a vast expanse, unless they were on a slow conveyor, etc.

 

[COLObrewer]

I have found that the hops lose some of their pungency. There is probably a chemical equation that explains the process by which sunlight would cause the alpha acids to breakdown, I don't have it though... I have been blessed with a room in the house that gets ridiculously warm in the late summer/early fall and have just continued to dry out my hops there on an improvised rack made of 2x's and window screens. Works well for me.

Sorry, that isn't data, Just personal experience...

Yes, I am also blessed with a way to dry hops in the shade, but as my harvest increases I run out of room, that's why I would like to know, why not in the sun?

 

[hopmomma]

The research I have found that supports the ideals of not sun drying is cross contamination. Such as animal hair and dander, bug residu, and pollens from other plants. Also you risk uneven drying, and overdrying. Other than that, it is possible to use sun to dry hops.

 

[pcollins]

Yeah, I've wondered about this, too, and couldn't come up with an answer aside from the skunking issue.

But... They grow out in the sun and do quite well there. Is it something that happens as soon as their pulled off the bine? Could it be that the renowned hop growing areas have unreliable sunny weather around harvest time so they traditionally tried indoors only because that was reliable?

The pest thing is another moot point in my opinion. They've already spent a chunk of time outside so why would post harvest change anything wrt contamination?

I'm harvesting this weekend and was just going to dry in my basement with a de-hu and a fan for the reason of the weather.

 

[nootay]

i dried my cascade outside this year. i put them on a screen with a fan under them, and a piece of cardboard about 6 inches over top of it so it would not be in direct sunlight. They turned out just fine taste wise

 

[ThreeDogsNE]

My first thought would be losing them to the breeze. The cones as they dry get amazingly light. If they are not secured between screens, I would be concerned about blowing them away.

Sunlight should not skunk the alpha acids until they are boiled. The isomerization that happens with boiling leaves them susceptible to skunking. Not an issue before the boil. Pests? They've seen it all before. But I would want a top screen before leaving loose cones out in the wind.

 

[Jagdad]

The commercial guys dry them as quickly as possible with supplimental heat/forced air - the quicker the better - They have a very specific temp range and drying times. It is all very controlled so the same brewing profile is maintained over large quantities and batch to batch. Their method drives out pests, removes small particulates, destroys fungal spores and minimizes the time the cones are exposed to heat. (Heat destroys oils and resins). Sun drying does none of the above. Cones also contain chlorophylls and pigments that continue to produce things like alkaloids and ketones that can't be removed from the cones because they are detached from the bine. Kinda like you ever notice a melon can sit in hot sun all season attached to the vine, but goes to hell in 2 days if picked and left in the sun? Commercial guy's hops are competing in a very competitive market for premium quality - I think they got it pretty well figured out. "Just cause you can, doesn't mean you should." I know- not data - just my 2 cents worth.

 

[COLObrewer]

The commercial guys dry them as quickly as possible with supplimental heat/forced air - the quicker the better - They have a very specific temp range and drying times. It is all very controlled so the same brewing profile is maintained over large quantities and batch to batch. Their method drives out pests, removes small particulates, destroys fungal spores and minimizes the time the cones are exposed to heat. (Heat destroys oils and resins). Sun drying does none of the above. . . . . . .

Why not? It seems to me that you could spend less money devising some sort of slow rolling adjustable speed drying conveyor to run through a greenhouse from one covered building to the next? From picker building through dryer greenhouse to conditioning building, etc.

I suppose a cloudy day would ruin that but can you pick hops in the rain?

 

[Retrofit]

Space is as much a premium as time. It seems like your asking why the pros don't toss out their successful working system for something that needs to be invented, built, tested, and tweaked.

The home brewer and grower has many luxuries that the pro's, who derive thier income from this crop do not. Not picking a fight, just tossing that out there.

I've fooled around with drying methods and maybe someday some home grower will build something that scales up to address hundreds on acres and that will be the next big thing.

I dry mine no heat, on screens. I don't have clients so what's fine for me is fine by me.

 

[Jagdad]

Using a greenhouse to dry on a hot sunny day sounds good - but- the minute the sun goes down they turn into high humidity chambers. The moisture can literally condense and drip from the ceilings and walls unless you turn on a heater- and then what is the point? It might work if you directed the hot daytime greenhouse air thru ductwork to the hops in an out building during the day and then shut it down at night. Or you could take the hops out of the greenhouse every night- but that sure sounds like a hassle.

 

[COLObrewer]

Maybe the problem here is relative humidity and amount of sunshine, we are very dry here and it's been said we have sunshine 90% of the daylight hours throughout the year. I don't see why it would take days to dry the hops, it seems it would be a matter of hours to me. Also, would it not be easy to evacuate the humidity if a cloud rolled over? (Fans and such) I can dry my hops in the garage in the shade in probably 24hrs because it is so dry here.

I'm not asking the pros (or anyone else for that matter) to do anything, I am simply trying to determine why it is not done. Just because it has been the way they have done it forever doesn't mean it's not feasible to do it differently, I would think solar heat would be cheaper that fueled heat, like I say maybe it's a matter of humidity and such.

 

[GVH_Dan]

Jagdad has most of the answers correct. If hops, after picking, are left in the sun they photo-oxidation continues and pretty soon they are the same color as straw. At that point, they are pretty much useless.

Why heat? As you heat up the hops, you pass the boiling points of the aromas and oils. If you are above 110F, you have passed the boiling point of most of them and after enough time, your hops will be flavorless. If you go above 140F, the alpha acids start breaking down and you no longer have the bittering.

The reason the big guys add heat is to speed up the process. They basically have only 12 to 14 hours to get them dry and out before the next day's harvest is ready to be dried. The addition of heat reduces the relative humidity of the air, thus allowing the air to hold more water and desire more. So they are trading off quality/flavors for speed.

 

[COLObrewer]

Jagdad has most of the answers correct. If hops, after picking, are left in the sun they photo-oxidation continues and pretty soon they are the same color as straw. At that point, they are pretty much useless. . . . .

Yes, I see this every time I cut the bines and any cones left over turn brown in a day or two, what if you run them through sunlight say for only an hour or two after they're picked in very low humidity and low temperature? These are the conditions here right now during hop picking season.

Would this be enough time to dry them enough to be worth the effort? Any cost benefit to this? I as well as a couple of hop farmers here would like to know this, my neighbor has 10 acres planted and some will be at harvesting age next year so he is contemplating drying methods. I guess we'll have to experiment.

 

[GVH_Dan]

No sunlight. No heat, unless absolutely needed.

OK, I'm making the assumption that you want to produce the highest quality hop possible, meaning it has higher than the standard oil content, most of its aroma's and all the alpha's it started with. This isn't always the case (e.g. hops for alpha acid extraction) but smaller growers usually want to sell to craft brewers and home brewers that are excited about hops that smell like hops instead of straw.

Heat boils off oils, it drives away aroma and it can degrade the alpha acids. Sunlight is a form of heat and it has other deteriorating effects to the cones. Sunlight is not an option. Forget about it. If you want a solar collector to gather heat, go for it but you won't need it.

Why do I say that? You are in Colorado. You are in a desert. Look at the image I have attached:

This is a psychrometric chart. Along the bottom is air temperature along the side is absolute moisture content of the air. The lines that slant up from left to right are Relative Humidity. When you heat air up, you do not add moisture but it causes the relative humidity to decrease. For example, pick the point 80F and 40% RH, which is probably humid for you. Now heat the air up to 130F and you can see the RH has now dropped below 20%, probably below 10%.

So what? The lower the relative humidity, the more moisture the air wants to grab from the cones. So by lowering the RH, you can dry cones faster. But you are all ready in a desert, so you can't get the RH much lower...added to the fact that heat damages the wonderful flavors...and I would recommend an open system that just passes air over the cones.

If you want, feel free to e-mail me at [dan at gorstvalleyhops.com] and I can answer more of your questions. Pass it on to your neighbors as well. If they put in 10 acres, they should be harvesting now and practicing the drying process so they don't screw it up when it counts next year. I can't tell you how many people ship me samples to analyze that they think are dry but when they arrive, I open the bag and the rank smell of compost hits me and the whole package is rotten.

On the up side, rotten hops make incredible fertilizer for tomatoes. I dropped over 100 lbs on my bed last year and this year, I'm canning a bushel or two of tomatoes every week.

 

[Retrofit]

10 acres! I know some guys that lay them in trays in their barn , but I would say get over this light issue and figure out natural heat- like a warm barn. Your going to have so much hops you could ruin you yield as you mess with experiments!

 

[COLObrewer]

. . . . . This is a psychrometric chart. Along the bottom is air temperature along the side is absolute moisture content of the air. The lines that slant up from left to right are Relative Humidity. When you heat air up, you do not add moisture but it causes the relative humidity to decrease. For example, pick the point 80F and 40% RH, which is probably humid for you. Now heat the air up to 130F and you can see the RH has now dropped below 20%, probably below 10%.

So what? The lower the relative humidity, the more moisture the air wants to grab from the cones. So by lowering the RH, you can dry cones faster. But you are all ready in a desert, so you can't get the RH much lower...added to the fact that heat damages the wonderful flavors...and I would recommend an open system that just passes air over the cones. . . . . . .

Nice, thanx for that, I just assumed since everyone (commercial) is using a heated and forced air system around here that more heat is necessary. I should have guessed this since my personal hops will dry on screens in the garage without any air movement in a day if they are kept at a couple inches deep. Time will increase exponentially though if layers are added. We will experiment with ambient air drying, my neighbor pretty much just ran enough to test the picker and cut the rest down, most of it was a little old anyway.

 

[GVH_Dan]

...I just assumed since everyone ...

This is the problem with trying to replicate the large scale grower's method on the small scale. (Yes, 10 acres is still small scale.) They need heat to increase the moisture removal potential of the air so they can keep the airflow low enough to not blow away the hops...while getting it done in less than a day.

On the small scale, you should be able to move enough air through a short bed to get the job done without adding heat. There's lots of ways to do it.

 

[COLObrewer]

. . . . . (Yes, 10 acres is still small scale.) . . . .

I believe this, my neighbor went to Yakima a couple years ago to study methods and talks about the families there with thousands of acres of hops, can't imagine it.

 

[muelster]

No sunlight. No heat, unless absolutely needed.

OK, I'm making the assumption that you want to produce the highest quality hop possible, meaning it has higher than the standard oil content, most of its aroma's and all the alpha's it started with. This isn't always the case (e.g. hops for alpha acid extraction) but smaller growers usually want to sell to craft brewers and home brewers that are excited about hops that smell like hops instead of straw.

Heat boils off oils, it drives away aroma and it can degrade the alpha acids. Sunlight is a form of heat and it has other deteriorating effects to the cones. Sunlight is not an option. Forget about it. If you want a solar collector to gather heat, go for it but you won't need it.

Why do I say that? You are in Colorado. You are in a desert. Look at the image I have attached:

This is a psychrometric chart. Along the bottom is air temperature along the side is absolute moisture content of the air. The lines that slant up from left to right are Relative Humidity. When you heat air up, you do not add moisture but it causes the relative humidity to decrease. For example, pick the point 80F and 40% RH, which is probably humid for you. Now heat the air up to 130F and you can see the RH has now dropped below 20%, probably below 10%.

So what? The lower the relative humidity, the more moisture the air wants to grab from the cones. So by lowering the RH, you can dry cones faster. But you are all ready in a desert, so you can't get the RH much lower...added to the fact that heat damages the wonderful flavors...and I would recommend an open system that just passes air over the cones.

If you want, feel free to e-mail me at [dan at gorstvalleyhops.com] and I can answer more of your questions. Pass it on to your neighbors as well. If they put in 10 acres, they should be harvesting now and practicing the drying process so they don't screw it up when it counts next year. I can't tell you how many people ship me samples to analyze that they think are dry but when they arrive, I open the bag and the rank smell of compost hits me and the whole package is rotten.

On the up side, rotten hops make incredible fertilizer for tomatoes. I dropped over 100 lbs on my bed last year he and this year, I'm canning a bushel or two of tomatoes every week.

Hi, I am on the South Coast of Oregon. I am growing Cascade Hops. I am going to dry them in my food dryer with the heating element unplugged but the fan circulating air. My question to you is How do I know there officially dry before I vacuum seal them & ship to them to Arizona. Texting me is 541-514-6587 or email ecodude17@ gmail.com. It is Sunday, August 20th Thank You.

 

[day_trippr]

@muelster: weigh your wet hops. Then dry them until they weigh 1/5th the wet weight...

Cheers!

 

[OleBrewing]

i do not agree with the argument of oxidation and skunking of drying in the sun. i would say that is not of any concern if they were going to skunk by the sun they would be skunked when they are picked or oxidized.
My main concern would be the outsides would dry at a very fast rate leaving the inside wet when in direct sunlight or even get over dried. not a very even dry.