Drying Fresh Picked Hops w/ Fridge

[WissahickonBrew]

I know there are threads on this subject that go back to 2008 and I read a good many of them with all descriptions of processes and tips.

I started out following the advice of others and loaded my whole cone Centennials on an old window screen, set another on top to make a hop/screen sandwich, kept the whole thing out of the sunlight, laid it on saw horses in my basement, laid a box fan on top drawing air up through the sandwich, set a dehumidifier on high right next to it (drip pan over flowed twice) and lastly placed a small space heater adjacent with a small fan behind sending warm dry air over the entire rig.

After setting everything up, letting run it run for a day I walked back down and stared at the contraption I built and wondered "there has got to be a better way". Then it hit me!

When I cold crash my beer at the end of fermentation I lift the fermenter into the fridge along with the blow off tube and water pail the end of the tube rests in. I remembered how the water in the pail dissipates so quickly from the dehydration effects of the fridge and EUREKA! I heard distant sirens and angels voices singing...

The fridge (any fridge) is a natural dehumidifier! And it's running anyway in everyone's house! I got mine 2nd hand a while ago, cleaned it up and replaced the gaskets. I spread a large cotton towel across the shelves and dumped the cones evenly across. Voile!

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[Jonas217]

Very interesting How long does it take to dry the hops?

 

[day_trippr]

More importantly, will the hops reach less than 20% of their wet weight before mold or mildew gets to them...

Cheers!

 

[WissahickonBrew]

They've been in the fridge for 1 day so far, and feel dry as paper right now.

Very interesting How long does it take to dry the hops?

 

[WissahickonBrew]

Here's my take on that: I put all of my foods into a fridge to PREVENT mold and mildew from growing on them, so I deduce this is the best way to prevent that from happening to my hops. I suspect they'd be more vulnerable sitting out in a shed/garage/basement than in a sealed climate controlled chamber!

More importantly, will the hops reach less than 20% of their wet weight before mold or mildew gets to them...

Cheers!

 

[day_trippr]

Here's my take on that: I put all of my foods into a fridge to PREVENT mold and mildew from growing on them, so I deduce this is the best way to prevent that from happening to my hops. I suspect they'd be more vulnerable sitting out in a shed/garage/basement than in a sealed climate controlled chamber!

That's a rookie mistake right there, and you hate to see that.

Mold and mildew most certainly will grow in fridges. Flourish, even.
Not that's necessarily going to happen, just something to watch out for.

Fridges retard spoiling bacteria growth, and not a heck of a lot more...

Cheers!

 

[WissahickonBrew]

LOL - Let's all agree that refrigeration "keeps food fresh" longer than if you left your perishables on the counter. BTW - if that's your tactic remind me to NOT accept any dinner invitations from you!

Let's save the microorganism pathology discussion for biology 101 class. I'm not claiming my suggested process will prevent mold and mildew from growing. But I'll bet your next pension check that mold and mildew will form a lot sooner OUTSIDE the fridge than INSIDE. My hop drying method is INSIDE the fridge! Feeling good about my "rookie" title right now!

That's a rookie mistake right there, and you hate to see that.

Mold and mildew most certainly will grow in fridges. Flourish, even.
Not that's necessarily going to happen, just something to watch out for.

Fridges retard spoiling bacteria growth, and not a heck of a lot more...

Cheers!

 

[GVH_Dan]

OK, you have the right idea but not all the facts.

When you are drying hops, or anything for that matter, the two major driving forces is the relative humidity of the air and the amount of air contacting the item. Think of the air as little cups that come along to scoop the water away. The lower the relative humidity, the more empty the cup is. The more air you pass over the item, the more little cups there are.

But then there is also the problem that the lower the temperature is, the smaller amount of moisture the air can hold...the cup is much smaller. So even if you get it to a very low relative humidity, it will take a lot of air flow to get the moisture whisked away.

Now think of how a refrigerator works. You have the freezer and the refrigerator. The air is cooled in the freezer and then allowed to leak over into the refrigerator cabinet. When it leaks back to the freezer section, it carries the moisture and it freezes (frost) on the coils until the unit goes into defrost mode.

The dangers are multiple. First, you will be asking for the freezer to go through many more defrost cylces than normal. So its possible that either you will overload the compressor or the defrost cycle won't be long enough and you'll ice the coil up. Second, you are removing a lot of water so in normal air you can go from 80% moisture content to about 40% overnight pretty easily. With the refrigerator, you may not be able to do that. It will probably take longer because there is reduced airflow and all moisture must be removed by the coils. True you are at refrigerator temperatures so that will slow oxidation and general spoilage but its a race. Finally, when it gets down to that last little bit of moisture, the relative humidity may not be low enough to get the moisture out. While the refrigerator can dry, the relative humidity is still at least 60% or above in most units. At that RH, the last moisture you need to remove will prefer to stay in the hop instead of coming out.

Start them out in the garage or on a porch spread thin on a screen with some airflow. After 24 hours move it next to your dehumidifier to finish them. Or if you want to try the refrigerator, do it at that point. if the freezer runs at a low enough temperature, it may still be able to pull the moisture out of the hops.

 

[WissahickonBrew]

Here's a few facts:

The water in my fermenter's airlock pail disappears quickly, very quickly when I cold crash. It might be magic, but the fact is, it goes poof!

There is no freezer in my fridge so you lost me with the part about water leaking into the refrigerator cabinet.

There is however a drip pan UNDER the fridge which collects the moisture pulled from the refrigeration chamber. I'm thinking this water came from whatever moisture was in the fridge?

Not trying to change everyone's thinking on how to dry their little batch of hops they just picked in their back yard. Only offering a tip on something that actually works.

OK, you have the right idea but not all the facts.

When you are drying hops, or anything for that matter, the two major driving forces is the relative humidity of the air and the amount of air contacting the item. Think of the air as little cups that come along to scoop the water away. The lower the relative humidity, the more empty the cup is. The more air you pass over the item, the more little cups there are.

But then there is also the problem that the lower the temperature is, the smaller amount of moisture the air can hold...the cup is much smaller. So even if you get it to a very low relative humidity, it will take a lot of air flow to get the moisture whisked away.

Now think of how a refrigerator works. You have the freezer and the refrigerator. The air is cooled in the freezer and then allowed to leak over into the refrigerator cabinet. When it leaks back to the freezer section, it carries the moisture and it freezes (frost) on the coils until the unit goes into defrost mode.

The dangers are multiple. First, you will be asking for the freezer to go through many more defrost cylces than normal. So its possible that either you will overload the compressor or the defrost cycle won't be long enough and you'll ice the coil up. Second, you are removing a lot of water so in normal air you can go from 80% moisture content to about 40% overnight pretty easily. With the refrigerator, you may not be able to do that. It will probably take longer because there is reduced airflow and all moisture must be removed by the coils. True you are at refrigerator temperatures so that will slow oxidation and general spoilage but its a race. Finally, when it gets down to that last little bit of moisture, the relative humidity may not be low enough to get the moisture out. While the refrigerator can dry, the relative humidity is still at least 60% or above in most units. At that RH, the last moisture you need to remove will prefer to stay in the hop instead of coming out.

Start them out in the garage or on a porch spread thin on a screen with some airflow. After 24 hours move it next to your dehumidifier to finish them. Or if you want to try the refrigerator, do it at that point. if the freezer runs at a low enough temperature, it may still be able to pull the moisture out of the hops.

 

[GVH_Dan]

Here's a few facts:

The water in my fermenter's airlock pail disappears quickly, very quickly when I cold crash. It might be magic, but the fact is, it goes poof!

Of course, its evaporating. That's what happens in a refrigerated environment. The coil is there to remove heat but to do that, it must be colder than the air setpoint. (Heat moves from warm to cold.) Along with the sensible heat removal you get latent heat removal (moisture). The dewpoint of the air is reduced to the surface temperature of the coil.

There is no freezer in my fridge so you lost me with the part about water leaking into the refrigerator cabinet.

OK, you have a refrigerator only. It still has coils that are cooler than the air set point. Hopefully they are running wet, meaning the temperature of the refrigerant is above 32F. In that case, it will do a better job of removing moisture from the air as it won't have to go through defrost or potentially ice up.

There is however a drip pan UNDER the fridge which collects the moisture pulled from the refrigeration chamber. I'm thinking this water came from whatever moisture was in the fridge?

Yep, you are correct. The water removed from the hops has to go somewhere. If this was a normal refrigerator/freezer combo, that water would be drained off the coil when it goes through the defrost cycle. It collects in the drip pan where the heat of the compressor and condenser are used to evaporate it.

Not trying to change everyone's thinking on how to dry their little batch of hops they just picked in their back yard. Only offering a tip on something that actually works.

If this works for you, go for it. I've run experiments using this technique, freeze drying, vacuum cooling, microwave, infrared, etc. I just want to make sure everyone understands the risks of doing it this way. Ignoring the minor threat to your refrigerator's continued performance, the bigger danger is that you won't get them dry enough. If you look up the isotherm for hops, it needs air at about 50% RH or less to easily get below 20% moisture content. Most refrigerators run an RH of 80% or above.

That said, when I tried drying in a refrigerated environment, once I hit 30% moisture content, the process slowed down to around 1% moisture loss per day. In other words, to get my hops down to 10%, it would have taken 20 days of drying or more (I didn't actually wait that long). True, at those moisture contents and temperatures I was not concerned with any damage mechanisms...it just took way too long.

 

[WissahickonBrew]

Are there instruments readily available to check ambient RH?

 

[HopJuicer]

I'm sure there are some high priced gadgets out there, but would a reptile humidity gauge work? I use to get them for 6 or so bucks or so. Might be worth a try.

When i cold crash I usually take the airlock or blowoff off and cover with sanitized foil until it's as cold as it's going to get, then put the airlock back on. When I don't do this, it creates a vacuum and has sucked the liquid from the airlock right back into the carboy. Maybe that's why it's like magic?

 

[LeftyRighty]

I've got to throw my experience in here.....
Use of a refrigerator for drying is a good idea, you're just using it incorrectly.
First, recognize, as a rule-of-thumb, that for each 10 degree rise in temperature, air will hold twice as much moisture (humidity). Just google lbs of water per cu ft of air at temp & relative humidity, or something like that.

You want warm air in the frig, not cold, and you need to vent it. This is the quickest way to dry your hops.

I have a refrigerator, put an empty crockpot in the bottom, plugged into a remote electric temperature controller (with temp probe inside refrig), drilled hole near top & bottom of refrig for PVC vent pipe (top pipe has ball valve for air flow control). Crockpot provides controlled heat, mine is currently set at 95-100 degrees. Vents provide gravity air flow, stack effect (warm air rises).

I will be drying my hops in this, when the cones are ready. I just harvested my small backyard barley crop, and am drying the kernels before storage.

Am also going to use this refrig for malting my barley. Crockpot with water will provide heat and moisture at ideal temp & relative humidity. When grains have sprouted, dump the water from the crockpot, continue with dry heat to dry the grain. Note: the ball valve in top vent is to control RH, reduced air flow will increase the RH.

Note: The last 7 years, I've grown tobacco, and used this refrig as a kiln to age/ferment my cured crop, at 120-125 temp and 75-80% relative humidity. This is to excelerate the aging process - 4 weeks at this temp/RH is about equal to one year of warehouse aging.

 

[GVH_Dan]

Are there instruments readily available to check ambient RH?

There are but they are chilled mirror dew point sensors...they start at $600 and go up.

You can use a $2 humidistat, but the closer to freezing you get, the more inaccurate they are. Basically, they are either camel hair, human hair or a polymer that expands and contracts with temperature and moisture. At low temp, they don't move enough to be accurate. Below freezing, they don't move at all.

 

[WissahickonBrew]

:cross:

My fermentation chamber is a 1/2 barrel vessel with 1/2 inch blow off tube in a pail. No fluid from the pail has ever been drawn back into the fermenter due to the pressure inside created by the yeast/fermentation process. Even at the lowest (above freezing) temperatures yeast activity continues, albeit reduced.

I'm sure there are some high priced gadgets out there, but would a reptile humidity gauge work? I use to get them for 6 or so bucks or so. Might be worth a try.

When i cold crash I usually take the airlock or blowoff off and cover with sanitized foil until it's as cold as it's going to get, then put the airlock back on. When I don't do this, it creates a vacuum and has sucked the liquid from the airlock right back into the carboy. Maybe that's why it's like magic?

 

[WissahickonBrew]

Went to HD last night and picked up a $10 humidity meter that measures/records highs and lows of relative humidity and also temperature highs and lows. I researched it online prior to purchase and dozens of P2P reviews gave it high marks for reliability.

I set it in my fridge amongst the hops and discovered Dan's posts are chock full of of accurate information. The meter reading dropped to 16% RH almost immediately. I came back periodically for curiosity sake and noticed the RH had climbed to 90% RH! Another checked revealed it went back down to 16%! Obviously the unit was cycling between the extremes in RH while the temperature remained constant!

Not sure what to do with this new data except to say thanks Dan for your in-depth and thoughtful insights!

There are but they are chilled mirror dew point sensors...they start at $600 and go up.

You can use a $2 humidistat, but the closer to freezing you get, the more inaccurate they are. Basically, they are either camel hair, human hair or a polymer that expands and contracts with temperature and moisture. At low temp, they don't move enough to be accurate. Below freezing, they don't move at all.

 

[WissahickonBrew]

Whew!

I was seeking EASY hop drying - but I appreciate your $.02!

I've got to throw my experience in here.....
Use of a refrigerator for drying is a good idea, you're just using it incorrectly.
First, recognize, as a rule-of-thumb, that for each 10 degree rise in temperature, air will hold twice as much moisture (humidity). Just google lbs of water per cu ft of air at temp & relative humidity, or something like that.

You want warm air in the frig, not cold, and you need to vent it. This is the quickest way to dry your hops.

I have a refrigerator, put an empty crockpot in the bottom, plugged into a remote electric temperature controller (with temp probe inside refrig), drilled hole near top & bottom of refrig for PVC vent pipe (top pipe has ball valve for air flow control). Crockpot provides controlled heat, mine is currently set at 95-100 degrees. Vents provide gravity air flow, stack effect (warm air rises).

I will be drying my hops in this, when the cones are ready. I just harvested my small backyard barley crop, and am drying the kernels before storage.

Am also going to use this refrig for malting my barley. Crockpot with water will provide heat and moisture at ideal temp & relative humidity. When grains have sprouted, dump the water from the crockpot, continue with dry heat to dry the grain. Note: the ball valve in top vent is to control RH, reduced air flow will increase the RH.

Note: The last 7 years, I've grown tobacco, and used this refrig as a kiln to age/ferment my cured crop, at 120-125 temp and 75-80% relative humidity. This is to excelerate the aging process - 4 weeks at this temp/RH is about equal to one year of warehouse aging.

 

[mlafnitzegger]

I'm sure there are some high priced gadgets out there, but would a reptile humidity gauge work? I use to get them for 6 or so bucks or so. Might be worth a try.

When i cold crash I usually take the airlock or blowoff off and cover with sanitized foil until it's as cold as it's going to get, then put the airlock back on. When I don't do this, it creates a vacuum and has sucked the liquid from the airlock right back into the carboy. Maybe that's why it's like magic?

Use a Bubbler air lock instead of the three-piece to crash with. It is designed to prevent the back pressure from drawing the sanitizer into the wort.

Sorry, off topic sort of but thought i'd share... :rockin:

 

[GVH_Dan]

Not sure what to do with this new data except to say thanks Dan for your in-depth and thoughtful insights!

No, thank you. I have ice arena clients that use those cheap humidistats all the time despite my warnings of their inaccuracy. I never thought of telling them to put the units in a refrigerator. I'll have to try that out on a curling club manager I'm working with to see if it convinces him.

 

[WayFrae]

Here's a few facts:

The water in my fermenter's airlock pail disappears quickly, very quickly when I cold crash. It might be magic, but the fact is, it goes poof!

Actually, it doesn't go poof! It is most likely getting sucked into your fermenter. There is a pressure differential caused by the room temp air in the fermenter condensing as it cools and sucking the liquid out of the airlock.

 

[day_trippr]

Actually, it doesn't go poof! It is most likely getting sucked into your fermenter. There is a pressure differential caused by the room temp air in the fermenter condensing as it cools and sucking the liquid out of the airlock.

Yup. It ain't magic, that's for sure..

(I totally missed that part earlier. Woof! Hope the OP likes his brews Extra Tangy!)

Cheers!

 

[WissahickonBrew]

LOL

The OP's pale ale turned out being one of his best batches ever and won silver at a BA sanctioned contest. "tangy" was not on any of the judges notes however...

Yup. It ain't magic, that's for sure..

(I totally missed that part earlier. Woof! Hope the OP likes his brews Extra Tangy!)

Cheers!