Freezer burn

[Wendy DeBord]

At work I'm experiencing freezer burn on a couple of my items. This just began about 2 months ago in our walk-in freezer. Nothing else in the freezer seem's to be effected. I have very similar items stored exactly the same way inches apart and those aren't getting freezer burn.

Can anyone tell me more about freezer burn? Is there really anyway to protect items from it? Why would it just begin out of the blue with this freezer and only effect a couple items?

[jsolomon]

My understanding of freezer burn is a dehydration injury to your food. So the reason you have freezer burn on those items is whatever packaging they are in is not water tight. This could be due to someone careless having injured the packaging, or simple manufacturing errors.

I hope it's not much inventory that's affected.

[fifi]

Packaging is the key to avoiding freezer burn. The key is the permeability of the package to water vapor. In the freezer, water tends to sublime... water molecules leave the food product to precipitate elsewhere as ice. Plastics are particularly variable. Cheaper and typical polyethylene and polypropylene plastic are fairly permeable. Some of the newer freezer bags are a thicker form of those plastics in a particular molecular configuration that is less permeable than the more common form. Some of the more sophisticated packaging has a layer of PET (same plastic as soda bottles) to reduce the permeability. One of the most impermeable of the plastics is Saran, polyvinylidene chloride. Saran was invented by Dow and sold a few years ago to Johnson. I don't know if it is used all that much in freezer packaging. I also don't know what the plastic is that is used in the vacuum packaging but it is better than your generic plastic baggie.

Note that permeability works in other ways. If I have a particularly "pungent" product like pesto or a particularly delicate product like glace de viande or lard, I store them in glass canning jars. Glass and metal (the lids) are, for all practical purposes, impermeable. My sister threw some excess dill into a plastic jar one time and put it in the freezer. Even the ice cream tasted like dill.

[snowangel]

If I'm going to stick something in the freezer in plastic (meat, for example), I'll wrap it in two layers of plastic wrap and then a zip lock (from which I suck out all of the air). Yes, fifi, air is the culprit.

Edited to add: If I'm freezing meat that has been cooked, I always add a lot of fat so it doen't get that dry stringy texture. I don't think this is freezer burn, just something that may happen to pre-cooked meat?

Edited October 31, 2004 by snowangel (log)

[jsolomon]

Aluminum foil is also a good guard against flavor migration. If you find that the injured things are from one shipment or some other reason that causes you to suspect part of your inventory that is not burnt yet, you may want to simply wrap them in aluminum foil, provided their size, etc. does not prohibit this.

What fifi said about glass and metal is very true, and it doesn't even require a thick membrane of them to prohibit--well, hell--small molecule migration. Let's face it, molecules don't get much smaller than water.

Edited October 31, 2004 by jsolomon (log)

[jpdchef]

if you haven't changed your wrapping procedures,and this problem started recently,check the gaskets on you freezer doors.If they're not tight,you get alot of icing.

[Wendy DeBord]

if you haven't changed your wrapping procedures,and this problem started recently,check the gaskets on you freezer doors.If they're not tight,you get alot of icing.

←

Ah..........that could be happening. We have a cart in the freezer who's wheels can get a lined incorrectly preventing the door from sealing tightly.

O.k. the details will make your eyes roll, but I have to spill all the beans to correct this.

I have a metal cart for my use only with a door that closes tightly, inside our walk-in freezer. This is what I've been using to store frozen mini pastries for the past year and one half. None of my trays are wrapped at all. Pastries are taken out of this cart/cabinet frequently. The reason why I haven't wrapped the pastries is that it would ruin/crunch the decoration on the pastries and well that's how this place has been doing pastries for years with-out issue. Making mini's to order is out of the range of possiblities to solve this problem.

Each tray/sheet pan holds one or two different pastry types. So when assembling a mini pastry tray you would take out many frozen trays. Bring them into your room to tray/plate them. As your traying condensation does really build up and in no time at all (because I work in a hot room) there are water beads dripping off the bottom of each pan. So I wipe them off, when I'm finished I then replace the pans in the freezer until the next time I need them. BUT it takes a couple minutes for the trays to refreeze once their put back into the frozen cart so the condensation and ice forming does continue. Obviously I can't make or keep any crisp mini pastries under this situation.

So is this correct and the most likely answer: it is the constant condensation from taking out the pans and bring them to rapid rooom temp. that creates ice when I place them back in the freezer and it's that ice that's stealing the moisture out of some items?

[Smithy]

Can you use smaller trays so you aren't removing as many mini-pastries and putting them back each time? Maybe put small trays or plates on top of the larger one so you only have to lift 1 tray out? Another, slower (and maybe not practical) way would be to seal them into mini-containers or compartments that will keep them protected from the outside air - I'm thinking of a compartmented box of some sort that holds roughly the number of pastries you'd be needing in a single compartment.

[Toliver]

What sbout tranferring the contents to a new tray every time they are removed from the freezer? Is that do-able? Then you wouldn't have to worry about the trays forming condensation when you put them back in.

Or what about putting the pastries on parchment paper/silpats that can be easily moved from one frozen tray to a room-temperture tray?

edited to clarify

Edited November 1, 2004 by Toliver (log)

[fifi]

I am not sure where we are going with this but and I may have misunderstood, but...

The fact that you are removing the trays, they are picking up condensation from the air outside the freezer, then are put back in the freezer... Well, that would not contribute to freezer burn of other products. All you are doing with that operation is adding some to the moisture in the freezer. Whether or not that is adding to an icing problem in the freezer is a whole 'nother issue. (That would depend on the size relative to the amount of condensation... blah, blah, blah.)

The products that are getting freezer burn are just giving up moisture from the product, through the packaging, and into the air in the freezer.

[Smithy]

As I keep rereading this thread (when I should be doing other things) I think Wendy is saying that nothing is wrapped, and that it's her mini-pastries that are getting freezer burn. What I hadn't realized until now is that those pastries are inside a closed cart that has to come out of the freezer before she can pull out any trays. My suggestions, and Toliver's, for smaller trays or silpats or something like that won't help because of the access. If I'm reading this properly now, then the question is why this problem just started a couple of months ago. What's changed? Is the freezer humidity lower than it used to be? Is she opening the cart more frequently than she used to?

Wendy, one final question (for now): are you sure it's freezer burn? Can you describe what it looks like? When you first described freezer burn I thought of meat. I don't know what a freezer-burned pastry looks like.

Nancy

[Wendy DeBord]

As I keep rereading this thread (when I should be doing other things) I think Wendy is saying that nothing is wrapped, and that it's her mini-pastries that are getting freezer burn.  What I hadn't realized until now is that those pastries are inside a closed cart that has to come out of the freezer before she can pull out any trays.  My suggestions, and Toliver's, for smaller trays or silpats or something like that won't help because of the access.  If I'm reading this properly now, then the question is why this problem just started a couple of months ago.  What's changed?  Is the freezer humidity lower than it used to be?  Is she opening the cart more frequently than she used to? 

Wendy, one final question (for now): are you sure it's freezer burn?  Can you describe what it looks like?  When you first described freezer burn I thought of meat.  I don't know what a freezer-burned pastry looks like.

Nancy

←

I'm sorry if I wasn't clear. I have a closed door cart (inside the walkin freezer) that the pastrys are stored inside of. Inside that cart they are not wrapped, just open sheet trays of mini's. When I need to use these pastries I leave the whole cart in the freezer and pull out the specific trays of mini's I want. I take those mini's into my work room, which is warm. In a matter of a few minutes the frozen trays begin to sweat profusely. When I'm done taking the amount of mini's I need off those trays the trays go back into my closed cart in the freezer for storage.

I'm certain it's freezer burn. It looks weird on frosting. The frosting rises up a bit and cracks, turning whiteish. On choux dough the freezer burn is whiteish too. The freezer burn remains cracked and dry after the pastries have defrosted (so it's not just ice forming on the item). I haven't tasted them, so I don't know what they taste like.........and I'm not about to either.

The weird thing is: this only began a couple months ago. Prior to then I never had a hint of freezer burn. Lately, I'd say I'm probably opening my cart less then I used to.

Other weird thing is this is not happening to any other items stored in that freezer. Theres items that have been in there longer which show no signs of freezer burn. I have a second open air cart with cakes and mousses that are wrapped in saran and they are fine, as are all the chefs items.

It does seem to target frosting and choux paste items specificly so far. I have trays that have whipped cream, mousse, chocolate and those aren't forming freezer burn.

Why wouldn't freezer burn effect everything equally? If I knew why it's just begun, perhaps I could reverse that and prevent it from happening further. It greatly complicates my work and I'd like to solve this.

[Rachel Perlow]

How about if you take a sheet pan with you into the freezer and place the pastries you need onto it while remaining in the freezer? It is not good for the quality of your product to have them partially defrost and then refreeze numerous times. If it is too cold for you in the freezer, then put a hook up next to the freezer and keep a coat there.

Another option would be to not freeze them one type of item to a sheet. Instead, make assortment trays so all you have to do is pull out one sheet and you have your assortment ready to go straight into the oven.

[Wendy DeBord]

I'm typically working with numbers from 100 to 300 per order and I give each order a selection of 12 to 18 varieties.

If I attempted to do as suggested, keep assortments on my trays in the freezer so I would completely empty those trays per order.....the numbers and items would never work out. Because I have orders of varying size. And because I'm always making new mini's. In the end I'd have a mess of a few pastries on this tray, and a few on that.......and those would become waste because I rarely ever need just a couple of one variety.

It's more logical and practical to keep them in groups-all my eclairs together or all my carrot cake squares together. Once I use half a tray I do condense it with another selection I only have a half pans worth of too....and so on. Sometimes I'll have 4 or 5 different kinds on one tray and I do empty out that tray when I fill an order. First in, first out, etc...

[slbunge]

It seems to me that something has happened to your setup that is forcing this freezer burn. If you had success with your cart within a freezer approach before, it should work now. Essentially with your cart you are minimizing the airspace around your pastries which is what you want to do. Before you go changing your tried and true practices you may want to look at some of the mechanical systems with your freezer.

I would agree with the person who susbpected a gasket on the door of the walk-in or the perhaps even on the cart. Another potential issue is the 'de-icing' or defrost cycle of the walkin.

Another issue might be the performance of the freezer. For example, if the freezer temperature is higher than what it was before you started having the freezer burn problem then you might start looking at potential issues with the system. Easy things to check are the timing and length of the defrost cycle which will result in periods of higher temperatures while the system is driving ice off of the coils. Perhaps the condenser needs a charge or needs to be cleaned as it is struggling to keep up a bit more than usual. Are you loading more foods into the walk-in right before your cart goes in that would temporarily raise the temperature and allow significant moisture migration before freezing? Essentially all of these things would be about the walk-in temperature riding too close to freezing and allowing too much time for the pastries to cool.

A cheap recording thermometer from your freezer mechanic might help diagnose some of these problems.

Keep in mind, also, that when you see the tray sweating that the moisture is from the air in the warm room, not from your pastries. Seems to me that the layer of condensation on the frosting that you are most certainly picking should actually help buffer you from freezer burn because it will be what is evaporated as the tray goes back into your cart.

[jpdchef]

I'm not entirely clear on your production needs,but I've always been very clear on instructing my people to not refreeze stuff.Either do your pulls from in the freezer,or store thawed product in the fridge and make up the difference for your next order from the freezer.

[Wendy DeBord]

I'm not entirely clear on your production needs,but I've always been very clear on instructing my people to not refreeze stuff.Either do your pulls from in the freezer,or store thawed product in the fridge and make up the difference for your next order from the freezer.

←

Believe me, this is not ideal and certainly not something I want to do. But the reality of the situation forces me to do such. If I didn't re-freeze the waste would be HUGE! Ideally I don't let my trays defrost before I take what I need off them and return them to the freezer. On all previous jobs I'd made mini's and filled them to order to keep items at their best. This particular job will not conform for quality, they insist I conform to their needs. Soooooo I'm trying to do the best I can with-in my limitations.

Slbunge-you mentioned something I'm not familar with, didn't know about. Thermometers that record! Can I buy one myself, if so from where?

We do have a self-defrosting freezer and I wondered if it was acting up and that's why now things are burning for me.......but I need to make a case so my chef will pay to bring in a mechanic to check out a freezer that seems to be just fine for their product. I needed to eliminate that it's something I'm doing causing this to happen.

"Another issue might be the performance of the freezer. For example, if the freezer temperature is higher than what it was before you started having the freezer burn problem then you might start looking at potential issues with the system. Easy things to check are the timing and length of the defrost cycle which will result in periods of higher temperatures while the system is driving ice off of the coils. Perhaps the condenser needs a charge or needs to be cleaned as it is struggling to keep up a bit more than usual. Are you loading more foods into the walk-in right before your cart goes in that would temporarily raise the temperature and allow significant moisture migration before freezing? Essentially all of these things would be about the walk-in temperature riding too close to freezing and allowing too much time for the pastries to cool."

Is there a one scientific answer why an item becomes freezer burned?

Is it water being driven out of the product thru evaporation as the item freezes, so it's the process of how your freezing creating this?

Can moisture evaporate out of a frozen item, so it's how your handling the already frozen item creating the burn?

[slbunge]

Slbunge-you mentioned something I'm not familar with, didn't know about. Thermometers that record! Can I buy one myself, if so from where?

←

They aren't cheap but for $65 you can buy one that stores temp and time and then you plug it into a USB port on your PC and can plot out the trend (look here). Might be good to check the overall freezer compartement (outside of your cart) and then check the 'inside the cart' temperatures and compare.

As far as I know, freezer burn is due to localized drying of the food due to moisture lost to the rest of the freezer. Wrapping tightly in non-permeable plastic is certainly the best way to minimize freezer burn. The problem I was trying to address is one where the temperature cycles above and below freezing. If your freezer is doing that you will actually be encouraging more migration of water molecules from the baked goods.

Edited to add:

By the way, are the freezer burned items always on the same side of the rack? I ask because if you have some air circulation pattern inside due to a failed gasket you should see the burn happening in the same locations. Increased airflow will vastly accelerate sublimation (ice to vapor) or evaporation (water to vapor). Just a thought.

Edited November 3, 2004 by slbunge (log)

[Wendy DeBord]

Well I had a frustrating and enlighting day today. When I arrived at work I noticed that the freezer door was not properly closed. The latching device on top of the door was locked downward so you couldn't even manually close the door tight-until you reset the device into it's proper position.

I mentioned this to the chef, so the crew would double check when they leave the freezer. Apparently they all knew this problem already existed and no one told me. Then the chef added that someone had shut off the freezer last night, cause the morning crew discovered it was off. Naturally this angered me quite a bit. Here I am throwing out my time and efforts because of some dimwit.

I cleaned out my cart and moved several things around in the freezer..........and I did run into a couple other items showing freezer burn outside of my cart. So now I know it's not just happening inside my cart, whew. The cooks just haven't noticed it on their work yet.

I'm going to do my best to pressure them into buying a recording device or I'll buy it myself for x-mas (less stress is certainly a worthy gift) just to nail down who's so careless. I'm glad I took the time here to write about this and learn too. I might be back for more help, but for now I'm releived having more info. and insight. Thank-you everyone!

[Smithy]

One additional bit of information: there are also recording thermometers that plot the temperature right onto a chart for all to see. They're more expensive than the data logger slbunge mentioned, where you plug into the computer to plot the data, but some people are happier about looking at a live graph than about seeing some mumbo-jumbo come out of a computer. That terrific site (thank you, slbunge, for a new source!) has both types available.

[jsolomon]

Wendy,

It sounds like you've got something going on that is slightly different than freezer burn.

With your choux discoloring AFTER you pull them out, they frost up, etc. etc... What I think is happening is that you're pulling the water soluble things out of the choux and leaving the fat soluble things behind, which will tend to make the choux white and tasteless. So the problem is the humidity in the room that you're frosting them, etc etc. What I would suggest is a dehumidifier for that room.

And for your temperature chart recorder needs, Check out ebay. There are ones that record both temperature and humidity. I'd put one in the freezer, and one in the work room. Many of those are also data loggers, too. So, you can plot it as you go and store it on the PC.

Either way, you're going to need to be careful of the difference in humidity, actually dew point, between the two rooms. Too high of a difference, and you'll be in trouble with all manner of sweating and migration. The reason why it only happens on one area of the cart is probably due to air flow and heat flow.

Again, best of luck!

-j