Coffee: To Freeze or Not to Freeze? - Page 2

[CGP4]

I know this is an espresso site, but if you're ever bored, it would be interesting to apply the same study to another preparation method. With all the variables that go into properly preparing espresso, it's probably more challenging to find differences in the beans. Perhaps trying the frozen and unfrozen coffees in a "cupping" presentation, or even in a french press, might make it possible to zero in on some repeatable differences (if any).

[Ken Fox]

Hi. Very interesting and helpful article indeed. This somehow gives me hope regarding "preserving" coffee. After having tried the Black Cat (best aroma and taste to my mind). I asked my brother to send another pound back here in the Philippines. He included a pound of Artigiano from Vancouver. I decided to "glad wrap" it, twice, in its original package without taping the valve, and keep it in the freezer. It was, I believe, 11 days old then. After having enjoyed the Artigiano, I thawed the Black Cat on the 21st day. I pulled a shot and, to my dismay, the aroma was nearly gone. It tasted like ordinary espresso (though not a "sink shot) to me. Could it be that I hadn't sealed it well enough? I haven't measured the temperature of my freezer, but could it be not cold enough? Was it too "old" prior to freezing? Having great tasting coffee is a rarity here in the Philippines so stretching the life of the ones I am able to acquire from abroad is very important to me. Help!

Ron

Of course I don't know the answer. 11 days out from the roast is getting a bit long in the tooth anyway; I've had black cat a number of times but never when it was that old. Also, the coffee may have been exposed to some extremes of temperature en route to you.

Is it possible for you to take up homeroasting?

ken

[Ken Fox]

I know this is an espresso site, but if you're ever bored, it would be interesting to apply the same study to another preparation method. With all the variables that go into properly preparing espresso, it's probably more challenging to find differences in the beans. Perhaps trying the frozen and unfrozen coffees in a "cupping" presentation, or even in a french press, might make it possible to zero in on some repeatable differences (if any).

Jim Schulman has done exactly this and his informal results are reported towards the end of the article. He says he could differentiate between fresh and previously frozen, but with no more accuracy than he could distinguish between two different roast batches of the same coffee, neither of which had ever been frozen.

I believe it is his opinion that freezing does not cause significant "damage" to coffee that is used for other things besides espresso.

ken
p.s. I don't think I could ever be so bored that I would want to do another study on freezing and coffee

[ronpistolero]

Is it possible for you to take up homeroasting?

Hi Ken. Tell me how to roast a blend that I would be able to come close to how the black cat tastes like and I'll try it. Actually, a friend of mine gave me 100% Kona coffee and I tried roasting it. I did my very first batch via hot air gun to what I'd consider a light roast and I didn't like the taste. Too light, insignificant. (I'm really poor with adjectives). However, the next batch I did was very good. I "fried" the beans with the pan's glass cover on, constantly shaking the pan and "flipping" the beans as though they were pancakes. I did it until the beans were much darker, relatively lighter than the italian roast. It turned out to be very good.

[AndyS]

You may remember that Versalab brought their M3 espresso machine to the Seattle SCAA show, but weren't able to produce very good espresso with it. At the time they (and Mark from Kaladi, the roaster) were severely castigated by some for using coffee that had been frozen. This is interesting, from Kaladi's website:

Freezing is one practice that sets Kaladi Brothers Coffee apart from other roasting companies. We place our beans in the freezer directly after roasting so the staling process does not begin before you, the customer, purchase our coffee.

Staling occurs at room temperature regardless of how coffee is packaged; packaging alone cannot preserve freshness. For maximum freshness, store your coffee in the freezer.

To protect your beans from moisture damage in the freezer, it is important to use an air-tight container such as a glass or ceramic jar. Studies show coffee stored this way can last up to a year or more!

You may grind your coffee frozen- direct from the freezer. There is no need to thaw the beans before grinding. A side benefit to this method is less build up on your coffee grinder.

They don't even thaw it out before grinding!

[another_jim]

You may remember that Versalab brought their M3 espresso machine to the Seattle SCAA show, but weren't able to produce very good espresso with it. At the time they (and Mark from Kaladi, the roaster) were severely castigated by some for using coffee that had been frozen.

I think some us of were castigating more about the the coffee being roasted so dark that it tasted like a ten day old ashtray. On the other hand, I suppose it can pay to explore the market niche on the darker side of Starbucks.

[AndyS]

I think some us of were castigating more about the the coffee being roasted so dark that it tasted like a ten day old ashtray

I didn't hear that, I guess there were multiple castigation modalities.

[olypdd]

Ken,

That was a great deal of work my friend. I was impressed.

As I read through, (I admit I skimmed over here and there), I didn't notice any comment on refrigeration vs freezing. I buy my beans from Vivace, and get them either the same day they're roasted, or the following day. Schomer advocates refrigeration of purchased beans vs freezing. I do not recall why, but I believe it had to do with the potential of thawed beans gunking up the works of your grinder. Of course, for all I know, Schomer may have altered his opinion about this by now.

Anyway, I usually buy 3 lbs about every other week or so. I do see a deterioration in shot quality after a couple weeks or so in the refrigerator, but by then, a new order was on the way.

I guess if you're roasting and producing quantities that aren't going to be used up anytime soon, freezing may be a solution. I know that Montana Coffee Roasters advocate freezer storage. Whenever I have visited them, they stress that in spite of all the objections to this, that freezer storage is the best method of storage.

Rich

[Ken Fox]

Ken,

That was a great deal of work my friend. I was impressed.

As I read through, (I admit I skimmed over here and there), I didn't notice any comment on refrigeration vs freezing. I buy my beans from Vivace, and get them either the same day they're roasted, or the following day. Schomer advocates refrigeration of purchased beans vs freezing. I do not recall why, but I believe it had to do with the potential of thawed beans gunking up the works of your grinder. Of course, for all I know, Schomer may have altered his opinion about this by now.

Anyway, I usually buy 3 lbs about every other week or so. I do see a deterioration in shot quality after a couple weeks or so in the refrigerator, but by then, a new order was on the way.

I guess if you're roasting and producing quantities that aren't going to be used up anytime soon, freezing may be a solution. I know that Montana Coffee Roasters advocate freezer storage. Whenever I have visited them, they stress that in spite of all the objections to this, that freezer storage is the best method of storage.

Rich

Rich,

My impression, based on nothing, is that the rate of degradation of coffee after roasting is a function of storage temperature. If this is true, it would indicate that sealed refrigerator storage will slow down the rate of aging vs. room temperature storage. I would be careful, however, to have the beans in a sealed vessel of some sort because refrigerators, unlike most freezers, are full of food based odors and you would not want those to be absorbed into the roasted beans.

I can't come up with a good reason why refrigerator storage would be preferable to freezer storage, since in the freezer you really have a lot more time to get to the beans and if for some reason you don't get to them quickly, they are still in there waiting for you to use them. With refrigerator storage I think you might extend the shelf life by some percentage, but deterioration would continue unabated. Since I've not tested this, and what's more have no experience with it myself, I can't go any further.

I think you will find that there is precious little, perhaps zero, data behind the strongly expressed opinions of some against freezing.

ken

[miKe mcKoffee]

First, a belated Kudos for a great job Ken!

It'll be nice to be able to just post a link instead saying the same thing over and over.

My impression, based on nothing, is that the rate of degradation of coffee after roasting is a function of storage temperature. If this is true, it would indicate that sealed refrigerator storage will slow down the rate of aging vs. room temperature storage. I would be careful, however, to have the beans in a sealed vessel of some sort because refrigerators, unlike most freezers, are full of food based odors and you would not want those to be absorbed into the roasted beans.

I can't come up with a good reason why refrigerator storage would be preferable to freezer storage, since in the freezer you really have a lot more time to get to the beans and if for some reason you don't get to them quickly, they are still in there waiting for you to use them. With refrigerator storage I think you might extend the shelf life by some percentage, but deterioration would continue unabated. Since I've not tested this, and what's more have no experience with it myself, I can't go any further.

I think you will find that there is precious little, perhaps zero, data behind the strongly expressed opinions of some against freezing.

ken

Wholeheartedly agree. Seems often those who strongly eschew freezing coffee have never actually tried it just "I heard"!

Also agree freezing much more effective than refrigeration. Not based on any scientific evaluation just in the cup and years ago at that. Even though freezing roasted coffee isn't for my normal consumption now, it was before I started home roasting 6 years ago. And I do still freeze some, especially to have an emergency roast supply on hand and for returning from trips. And I have pulled 75% plus crema shots of 6 month plus frozen roasts, oh and they tasted pretty darned good too. Maybe not as good as directly 5 days rest from roast, but not like even 2 weeks stored at room temperature either. With the added caveat mine are always vacuum sealed rather than just sealed.

[Ken Fox]

Wholeheartedly agree. Seems often those who strongly eschew freezing coffee have never actually tried it just "I heard"!

Also agree freezing much more effective than refrigeration. Not based on any scientific evaluation just in the cup and years ago at that. Even though freezing roasted coffee isn't for my normal consumption now, it was before I started home roasting 6 years ago. And I do still freeze some, especially to have an emergency roast supply on hand and for returning from trips. And I have pulled 75% plus crema shots of 6 month plus frozen roasts, oh and they tasted pretty darned good too. Maybe not as good as directly 5 days rest from roast, but not like even 2 weeks stored at room temperature either. With the added caveat mine are always vacuum sealed rather than just sealed.

Thanks for the kind comments. When I return from my trip (in France at the moment) and from the SCAA, I have a couple week's worth of coffee in the freezer that will at that point be 5-6 weeks post roast date but frozen the entire time. I expect to have good results, and I won't have to rush to start roasting again, before I have time to pay some bills and put out other fires awaiting my return.

Most of the coffee that I consume now is not previously frozen, especially in the summer when roasting is less aversive than it is in the winter, living in a cold climate. Still, I honestly cannot tell the difference when I use the previously frozen stuff.

ken

[miKe mcKoffee]

Just for fun here's a video I took last October of coffee that was room temp' mason jar vac sealed 7 day rested, then 6 weeks vac jar frozen. FWIW the jar had been opened and beans for a shot removed then re-vac'd a number of times both while at room temp before freezing and after freezing. I just let the frozen beans for a shot thaw a few minutes in the grinder before grinding.

[gvideo]http://video.google.com/videoplay?docid=-7510195106277647437&hl=en[/gvideo]
Appears to be a good 90%+ crema end of shot Guinessing to ~45% 30 seconds post shot. This was my blend of 100% Arabica Caffe' Rosto roasted 15min gentle tickling a wee bit into 2nd profile roasted to light FC, 4min drying equalization stage to 300f, level ramp to start of 1st ~9:30, 15min end of roast cooled to 125f ~2min, pre-roast equal part blend of Aged Sumatra, Brazil Cerrado DP, Brazil Cerrado WP, Harrar DP and Kona WP. Shot pulled ~202f.

Yeah I know, shot went a tad long into a bit-o-blonding, was focusing on taking video. But hey still tasted pretty darn good, especially considering 7 weeks post roast!

Another time last year discovered some Monkey Blend that have been vac jar frozen for over a year after 9 days room temp. (Was part of left over coffees from hosting PNWG III) Those shots only 75 to 80% initial crema and still tasted pretty darned good but no video.

[Ken Fox]

There are no local cafes in my town that are worth visiting, and we have no roasters save the sample roaster in my garage . . . . .

But, there is a cafe and roaster 11 miles south in the next town that has gotten some favorable press in the local papers. I've never been there even though I drive through the town at least once a month.

A local restaurant which is basically Italian with some thin crust pizzas (Ciro; Jim S. and I have eaten there a couple of times), recently opened a gourmet foods store next door, and I've been visiting regularly since they have a reasonable cheese selection. I noticed that they had some valve bags of coffee in refrigerator section, and got to discussing this with the staff. Turns out, the coffee comes from this roaster south of here and arrives the day of or day after roasting. The roaster told them to store the valve bags in the refrigerator, and that this would extend shelf life by about a week. Touching the coffee bags they felt as if they were around 40 degrees F, which would be maybe 4C.

Assuming that the freezing experiment can have its results extrapolated to include refrigeration for shorter term storage, this is an interesting development to see happening in a small community . . . . . . in Idaho. While I don't think there will be many food stores that would do this, e.g. tie up refrigerator space for coffee, high end food markets could do this if they had good roasters from whom they bought their coffee in the just-roasted state.

ken

[cafeIKE]

A merely interesting, non-rigorous observation:

Three weeks in the freezer @ -20°C appears to give off approximately as much gas as 1 day @ +20°C for a freshly roasted espresso blend.

[ant]

I'd be curious about the types of coffee that can be frozen. In terms of what people are tasting in their frozen bean espresso, are they getting those floral and/or fruity aromas in the cup or are there 'freezer robust' flavours that come through? One particular local roaster recommends freezing but I have had a sneaking suspicion that they want to delay the onset of any smokyness/acridity that comes from their roasting style- their recommended usage window is from day 1 or day0, depending on who you talk to. A friend and I tried it about 7 days after roast and I swear I was slurping on an ashtray, and not one littered with expensive cigarettes either. It could just have been a very bad batch though, or they might be roasting with the idea that people will always put 2-3 sugars in their coffee.. who knows

[altoCalgary]

I'd be curious about the types of coffee that can be frozen. In terms of what people are tasting in their frozen bean espresso, are they getting those floral and/or fruity aromas in the cup or are there 'freezer robust' flavours that come through?

First, I would like to thank Ken and his friends for conducting such a rigorous experiment. Then I would like to respond to Ant's questions. My experiences are not based on a rigorous set of experiments, but rather on accumulated observations gleaned from daily espresso making at home.

By way of background, about 9 months ago I began freezing same-day-roasted beans from a local roaster in Calgary after I read about George Howell's storage methods for green beans.

Terroir green coffees are carefully monitored and, when the time is right, are placed in a freezer at minus 40 degrees Fahrenheit, stopping any change in its tracks.

I ordered the beans and the next day, I would drive over to the roaster and, within four hours of being roasted, pick up them up. I brought the 2.2 lb. valve bag home, and immediately placed it in my 20 cu. ft. deep freeze in a wire basket near the top. When I needed the beans, I would go downstairs to the freezer, open it up and while leaving the bag in the freezer, I would take a 1/4 cup scoop of beans out of the bag and then reseal the bag, using a mid-sized fold-back binder clip. To reduce the oxygen that might otherwise be introduced into an open bag and to maintain the carbon dioxide that accumulated in the bag after it was sealed by the roaster, I left the bag upright at all times in the freezer. I also assumed while in the freezer, accumulating carbon dioxide would force oxygen out of the bag into the freezer. (I now have learned from Ken's experiment that the valve may be frozen open or closed!) I found that by leaving the bag in the freezer while removing the beans and being quick, the beans remaining in the bag would stay frozen. My other concern was the fear that the beans would pick up some moisture from the warmer air above them when the freezer lid and bag were opened. I expect that this happens to some degree. I then closed the lid and took the beans upstairs to grind in my Mazzer Mini-E, tamp and then brew them in my Andreja Premium.

Previous to reading Howell, I had left the roasted beans on the concrete floor on my basement. This seemed to maintain better freshness longer than leaving them upstairs on my kitchen counter. For the concrete floor beans, they seemed at their best between 3 and about 10 days in terms of consistent depth and complexity of aroma and flavor. My frozen beans seem best between 4 and 14 days. I believe the freezing adds the extra three days. If I wasn't opening the bag each day everytime I brewed an espresso, I expect that the beans would maintain their excellent state for as long as Ken's experiment indicated. I am now planning a mini-experiment with beans of the same batch sorted into different smaller batches and frozen for different lengths of time to see if I can add some confirmation Ken's results.

Finally, my response to the question Ant posed that I quoted above. Whether I grind the beans frozen or let them sit awhile to thaw seems to make little difference in the cup. In fact, if the heating of the beans by about 10 degrees F during grinding in my Mazzer Mini-E B affects the taste in the cup, the frozen beans would likely counteract that effect. Also, I have brewed frozen beans from all over the world and they all seem to have the aroma and flavor I expect.

[Ken Fox]

I ordered the beans and the next day, I would drive over to the roaster and, within four hours of being roasted, pick up them up. I brought the 2.2 lb. valve bag home, and immediately placed it in my 20 cu. ft. deep freeze in a wire basket near the top. When I needed the beans, I would go downstairs to the freezer, open it up and while leaving the bag in the freezer, I would take a 1/4 cup scoop of beans out of the bag and then reseal the bag, using a mid-sized fold-back binder clip.

People will tell you that opening a bag of coffee out of the freezer, removing some coffee, then resealing and refreezing invites condensation and bean damage. I know of no proof on this topic, one way or the other, although it is a practice I would not recommend.

The shelf life of previously frozen roasted coffee is not measured in minutes; it is measured in days, probably more than a week. Therefore, it makes the most sense to freeze in semi airtight bags or containers that will supply enough coffee for at least a few days. You remove a jar or bag like this, let it degass to your preferred level, then use it over several days.

Even if condensation is a non-issue, you have to think about the other stuff you keep in your freezer. If it is a cold freezer, preferably a chest freezer, used for longterm storage, you will minimize freezer burn and extend the longevity of your other frozen foods by opening the freezer door as infrequently as possible, not to mention, you will save energy.

Best,

ken

[altoCalgary]

Therefore, it makes the most sense to freeze in semi airtight bags or containers that will supply enough coffee for at least a few days. You remove a jar or bag like this, let it degass to your preferred level, then use it over several days.

Even if condensation is a non-issue, you have to think about the other stuff you keep in your freezer. If it is a cold freezer, preferably a chest freezer, used for longterm storage, you will minimize freezer burn and extend the longevity of your other frozen foods by opening the freezer door as infrequently as possible, not to mention, you will save energy.

Thanks, Ken. Of course, you are right about the freezer issues. To help me gain some insight into your approach, over the next month or so, I plan to use your suggestion to divide my roasted beans into batches of a few days worth, place them in Mason jars in the freezer and take out one at a time to degass and then use.
Cheers,

Ron

[cannonfodder]

I have been following Kens lead lately in regard to freezing beans. I found myself with a mountain of coffee and did not want it to go to waste. I divide the beans into half pound lots, put them in sealed glass jars and drop them in the deep freeze. They get one trip into the freezer and one trip out. I give them at least 12 hours before I open the container.

[Ken Fox]

I have been following Kens lead lately in regard to freezing beans. I found myself with a mountain of coffee and did not want it to go to waste. I divide the beans into half pound lots, put them in sealed glass jars and drop them in the deep freeze. They get one trip into the freezer and one trip out. I give them at least 12 hours before I open the container.

Dave,

After you have tried some of this coffee, please let us know how well you think it has held up compared to how it was when fresh. And, let us know the details under which you froze it, such as how old it was when it went into the freezer, how it was packed, how long it was frozen, and at what temperature. Like you, I have frozen some partially degassed coffee, but the freezing article did not deal with this issue, so it helps to have a few data points on other approaches at the end of the article.

thanks,

ken