freeze roasted beans will lose flavor

[Vinitasse]

The concept of freezing beans must be controversial to attract such passionate posts. Of course fresh is best, thats not what the thread is about, its about freezing beans and chemically thats the best thing to do if they are stored for any length of time (beyond 4 weeks).

MrJack, you going to back up your statement with references or just troll?

I would much rather drink 8 week old coffee that had been stored in a cool, dark pantry than any coffee that had been in a freezer for any period of time.

[Journeyman]

Smokey, there is so much nonsense in this post I don't know where to begin. For starters, electons don't orbit (queue quantum physics).

Maybe he figured if he started talking same or different spin, people wouldn't have the foggiest what he was on about? So he went with classical rather than quantum concepts?

There are not many people comfortable with talking straight physics and there are already posts complaining about 'mumbo-jumbo.'

[smokey]

The concept of freezing beans must be controversial to attract such passionate posts. Of course fresh is best, thats not what the thread is about, its about freezing beans and chemically thats the best thing to do if they are stored for any length of time (beyond 4 weeks).

MrJack, you going to back up your statement with references or just troll?

[mwcalder05]

Coffee beans just have no place in the freezer! If you're having storage problems just buy in smaller batches or just drink up! That being said, I've used coffee a month old that has just been in a cool cupboard in a bag with a one way valve. It tasted absolutely fine! Not perfect but usable nevertheless. I've tried beans that have been in the freezer for a month and tasted dull, flat and stale. Save some freezer space for some more ice cream (even for those great tasting affogattos with that fantastic shot with beans stored in a cupboard!)

(Step off soapbox and kick it to the next suburb!)
Michael

Ps: apologies for sounding angry if i did.

[MrJack]

I love this thread so much that I am going to bump it!

The thread title, "Freeze roasted beans will lose flavour", deserves argument because there is no evidence besides hearsay on this thread one way or another.

OK, I want to argue the science behind staleness. Its all about exposure to Oxygen - O2. O2 is a very unstable and very reactive molecule, as an atom it has 2 electrons orbiting the nucleus, instead of orbiting in opposite directions they orbit in the same direction, this creates instability. When O2 approaches another molecule it grabs that molecules electrons which in turn destabilises them as well.

...

I welcome comments on this fascinating topic.

Smokey, there is so much nonsense in this post I don't know where to begin. For starters, electons don't orbit (queue quantum physics).

[Vinitasse]

Or better yet... don't freeze the beans... EVER!

Rather than compare meat left out in the sun vs meat that has been frozen... why not compare frozen vs fresh? Frozen will ALWAYS be second rate!

[smokey]

I can't claim much knowledge of food chemistry, but I'll ask the question; when we talk about degradation of coffee beans, part of it is oxidation, but I get the impression that it is also a function of the loss of aromatic compounds, some of which evaporate (possibly not the correct term so go ahead and correct me) faster than others.

Is that true, to the best of your knowledge, or no?

Dragunov21, thats a really good question, I haven't mentioned the essential oils / aromatic compounds and flavours. These have a lower boiling point than water, so warm temperatures will evaporate them, yes correct word

Part of what happens to the oils is they go rancid in the presence of oxygen and free radicals. When a cell breaks down or is injured oxidation starts up with a vengence, free radicals are formed and act as a second line of offense to further degrade the oils and proteins etc.

So yes, you are correct, once the roasted beans are exposed to air and temperature (and moisture), they will start to degrade due to these processes, - aromatic oils evaporate and they go rancid. In short they go stale

[smokey]

On another thread there are some comments about outgassing of CO2 from new beans. Do you think this would be something to wait for before freezing beans or might it be better to vac-pack and freeze immediately to slow the outgassing as well?

I don't have a roaster myself so can't test it - unless I can get my local guy to release beans direct from the roaster...?

Hmm, good question Journeyman, I think outgassing is part of the flavour development and therefore necessary, so I think it needs to happen before you freeze. But this is still an educated guess, hopefully someone will do a live experiment and let us know the outcome.

Just quickly, talking about flavour development, oxidation helps produce the flavours we enjoy, but it is a two edged sword.

[Dragunov21]

OK, I want to argue the science behind staleness. Its all about exposure to Oxygen

I can't claim much knowledge of food chemistry, but I'll ask the question; when we talk about degradation of coffee beans, part of it is oxidation, but I get the impression that it is also a function of the loss of aromatic compounds, some of which evaporate (possibly not the correct term so go ahead and correct me) faster than others.

Is that true, to the best of your knowledge, or no?

[Journeyman]

On another thread there are some comments about outgassing of CO2 from new beans. Do you think this would be something to wait for before freezing beans or might it be better to vac-pack and freeze immediately to slow the outgassing as well?

I don't have a roaster myself so can't test it - unless I can get my local guy to release beans direct from the roaster...?

[smokey]

I love this thread so much that I am going to bump it!

The thread title, "Freeze roasted beans will lose flavour", deserves argument because there is no evidence besides hearsay on this thread one way or another.

OK, I want to argue the science behind staleness. Its all about exposure to Oxygen - O2. O2 is a very unstable and very reactive molecule, as an atom it has 2 electrons orbiting the nucleus, instead of orbiting in opposite directions they orbit in the same direction, this creates instability. When O2 approaches another molecule it grabs that molecules electrons which in turn destabilises them as well.

This process is called Oxidation and is the foundation of disease and inflammation. We can use antioxidants like Vitamin C which replaces the stolen electron back to the damaged molecule to cure illness.

Oxidation plays a huge role in food spoilage, we cook, salt, tincture, smoke and dry foods to prevent oxidation aka food spoilage. We have even developed specific chemicals that will prevent and or slow the oxidation process in our foods, problems arise when we then ingest these chemical along with our food, but thats another thread.

Oxidation occurs only in the presence of O2, there are other biochemical pathways but lets stick to Oxygen and its oxidation process for simplicity's sake. Thus removal of O2 and we prevent oxidation.

Oxidation needs temperatures above freezing (although below 0 C oxidation events do occur but this is very very slow). So freezing your food (steaks, bananas, cakes, beans, etc) will slow the oxidation aka staling process.

Oxygen is part of water, H2O, so any moisture present will seep into the bean causing an avalanche of oxidation.

The question I am arguing is, "does freezing harm the roasted coffee bean's flavour?"

The answer should become obvious as we look at the fresh roasted bean. The roasted bean has its natural cell structure changed beyond recognition, temperatures of above 200 C will sure denature cell membranes, proteins denature and carbohydrates take on precarbon forms ready to burst into flame, the ultimate oxidation expression. All water and moisture is driven off during the roasting process, there is minimal to no water present in the bean at the time roasting stops.

Once the bean begins to cool it begins to oxidise in the presence of air forming flavour compounds and eventually rancidity and staleness. There is no way to stop oxidation at this stage of the now warm and dry bean. The roasted and therefore very dried beans, are now extremely hydroscopic, they are now active water seekers, the bean cells are as dry as a dead dingo's donga and will absorb massive amounts of O2 rich moisture if allowed to. If water is allowed to seep into the bean at this stage oxidation will occur at a rapid pace. It is difficult to prevent if you roast on a humid day, but air contains moisture anyway so leaving them out uncovered for too long is not good.

If there is high humidity present then the pulled roasted beans will immediately soak up this moisture.

Once the beans have been cooled they are put into a plastic bag or container and placed in a cool place. But this too presents its own problems because there will be a small amount of moisture and there will be air in and around the beans regardless of how careful you have been. Thus we have the window of 3 to 8 weeks while the beans slowly go stale/oxidise.

So now we need to see how temperature affects oxidation/staleness. Anything above freezing will oxidise faster than below freezing. If you can freeze your beans with minimal air/O2 and with minimal humidity then you are going to reduce the rate of oxidation inside the bean. In other words freezing your fresh-roasted coffee beans WILL slow the staling process, its basic chemistry, drop the temperature and oxidation slows.

An example, leave one of your t-bone steaks out in the sun and the leave the other frozen and see which one oxidises/goes rancid the fastest.

Does freezing affect the flavour of the bean? Not in the short term, but yes in the long term, oxidation continues while frozen, but at a much reduced pace. The quality of flavour should remain much longer than beans not frozen for the same length of time. For example, beans frozen and thawed at around 2 months should initially taste awesome compared to a pack of beans stored in the cupboard for 2 months.

However, once thawed, the beans will begin to oxidise in earnest, so they will not last as long once thawed, so don't expect them to last the usual 3 to 4 weeks. I would recommend using them up to 2 weeks max.

A long winded lecture I know, I hope it explains oxidation and staling, I studied food technology and chemistry many years ago and worked in the food industry for some years so know a little about this topic

I welcome comments on this fascinating topic.

[Dragunov21]

Dude. Seriously.

[Hamburglar]

I have experimented with freezing, and therefore have visited both sides of the coin... objectively... and very quickly concluded it was a crap storage medium

Yes! Now that's the kind of stuff that's useful. Why not just say it at the beginning? Rather than talking at us like you're Illy reincarnated and inventing "facts" about physical/chemical changes happening inside the bean during freezing. There would be no reason to misquote then try to spin "some" clever english to justify it.

[Vinitasse]

Incidentally, I think Hamburgler had a Behmor roaster, and would likely know just as much about fresh coffee as anyone else here.

I wasn't aware that the ownership of a Behmor was recognized as proof of such knowledge. Has that credential been peer reviewed?

[papagoose]

With regard to the modified quote, I emphatically disagree that "probably" is an unscientific word- it pertains to the level of certainty of the conclusions, and there is a world of scientific difference between "probably does" and "does". But in any case, the science is lacking. This particular quote is from the SCAA's newsletter. The things that jump out at me are that the people supporting freezing are "some" anonymous people, and that the argument against freezing is based on an uncited conclusion from the SCAA Technical Standards Committee based on uncited 'limited testing', the nature and results of which are unknown. Neither conclusion is particularly strong. The statement about moisture and lipids emulsifying lacks detail and is uncited, and there is also no evidence provided to justify the statement that the effect of this is "probably accelerating oxidation". Some have argued that temperature does make a difference, but that oxygen and moisture are the most important factors (as expected) Predicting Algorithms for Oxygen Uptake and Shelf Life of Dry Foods and the Application to Coffee. These authors only went down to 4 degrees though, not freezing, and the results are based on ground coffee so they are not directly applicable here either. I also don't believe this was peer-reviewed.

Confirmation bias is likely to play a significant role when tasting as well. Vinitasse has experimented 'objectively' with freezing, and finds freezing to significantly degrade the coffee, but the details of the experiments are not provided. I would suggest that unless it was at the very least a blind test, the results do not generalize. Of everything I have seen, HB's 'To freeze or not to freeze' is the most rigorously justified viewpoint, regardless of the possibility of "fudged results and hidden agendas" - at least there *were* results for a change, and the results were even provided for all to see! There is always the possibility of hidden agendas- so in the absence of substantive claims I'm not convinced that this is an adequate criticism of the HB article.

I don't think anyone is disputing that fresh is preferable to frozen, but it *is* a valid question to ask how long coffee needs to be kept before storing in the freezer is preferable. Is 3 weeks in the freezer better than 3 weeks on the shelf? 4 weeks? 6 weeks? Pretty much everyone agrees that you need to store coffee in an airtight container, ideally with a one-way valve, with minimal moisture, and away from sunlight. The fact that there is this level of uncertainty about freezing suggests to me that the effect of freezing is not likely to be on par with these other factors, and would be much more minimal (which is the same conclusion as the linked article). As with most others here, I don't see any need to freeze my coffee any time soon. Incidentally, I think Hamburgler had a Behmor roaster, and would likely know just as much about fresh coffee as anyone else here.