Not enough data to call it evidence, but I'm seeing a trend that warmer beans extract better. Done a few experiments where I took the beans after weighing the dose and allowed them to warm on the cup warming tray on the espresso machine. This brought them up to about 94-95F (about 35c). Interestingly, the pull is a little faster, but the TDS is higher. Not willing to place a number on it yet, but it is measurable. I think this confirms the research the developers of the N.S. Mythos-1 Clima-Pro found. Flavor wise, it seems to bring out more of the thicker, tongue-coating sticky quality.

My winter time room temperature is about 65f (18c), so this would likely be similar to the effect of a hopper full of beans sitting in a hopper on top of a big warm electric motor in a busy cafe.

Need more A/B data to compare - which is really tedious and hard to do in a home kitchen. It would be a snap to do in a well-equipped laboratory with multiple machines and grinders and temperature controlled chambers to hold beans in. And some lab assistants to do all the work.

There were a fair amount of members reporting enthusiastic results by microwaving, sous vide, or other means of heating their beans before grinding them: Sous Vide Espresso Extraction-WBC finalist Dawn Chan Kwun Ho

I wonder if people are still keeping up with it.

Matt Perger has been advocating for the opposite recently. Freezing of beans to help the bean shatter and create fines when grinding.

I'm interested in a combination of the both. It would be interesting to see a freeze pre grind but sous vide post grind. Assuming that you could get from the grind to the portafilter with the warming taking place in between in a reasonable time.

Does anyone have any input on how much complication this adds to the routine vs the difference in the cup?

Edit:
This is a great article that provides some ideas as to why bean temperature coincides so heavily with TDS.
https://strivefortone.com/2016/05/18/th ... re-rehash/

So, I pulled two samples of the same coffee beans last night, one at room temperature of about 68f (20c) and one in my freezer for 30 minutes at 0f (-18c).

The grinder was purged with a gram of room temp beans just ahead of each pull. The grinder was set prior to get the desired brew params for room temperature beans. (17g dose, 34g beverage in 30s at 199f (93c).

The bean charge was slightly greater than necessary and the final weight of the dose was carefully measured to be exactly 17.0g.

The room temperature pull proceeded to produce 34.1g in total pump time of 29s. The TDS after filtering and cooling was 9.68%.

The frozen beans were ground with identical settings and the basket carefully weighed and adjusted to the same 17.0g. The pull produced 32.9g of beverage in 41 seconds. The TDS measured 10.28%, after filtering and cooling.

The net effect of the experiment produced results consistent with a "tight grind" - namely that grinding finer for slower pull time produces greater TDS.

Not sure why the pre-frozen beans pulled at such a different rate. But it did. Unfortunately, to really validate all of this would require multiple samples, which I didn't have time to accomplish. Also unsure if the experiment should include adjusting the grinder with several samples of frozen beans to achieve the expected output/time relationship. So I cannot say it increases TDS. I can say, it appears to increase pull time and the need to grind coarser.

jhors2 wrote:I'm interested in a combination of the both. It would be interesting to see a freeze pre grind but sous vide post grind. Assuming that you could get from the grind to the portafilter with the warming taking place in between in a reasonable time.

If you sous vide them after, you remove the reason why the beans would shatter in the grind and produce more fines. According to the study matt perger participated in, the beans need to be frozen at the time of grinding for the increase in TDS to be observed.

nuketopia wrote:So, I pulled two samples of the same coffee beans last night, one at room temperature of about 68f (20c) and one in my freezer for 30 minutes at 0f (-18c).

The grinder was purged with a gram of room temp beans just ahead of each pull. The grinder was set prior to get the desired brew params for room temperature beans. (17g dose, 34g beverage in 30s at 199f (93c).

The bean charge was slightly greater than necessary and the final weight of the dose was carefully measured to be exactly 17.0g.

The room temperature pull proceeded to produce 34.1g in total pump time of 29s. The TDS after filtering and cooling was 9.68%.

The frozen beans were ground with identical settings and the basket carefully weighed and adjusted to the same 17.0g. The pull produced 32.9g of beverage in 41 seconds. The TDS measured 10.28%, after filtering and cooling.

The net effect of the experiment produced results consistent with a "tight grind" - namely that grinding finer for slower pull time produces greater TDS.

Not sure why the pre-frozen beans pulled at such a different rate. But it did. Unfortunately, to really validate all of this would require multiple samples, which I didn't have time to accomplish. Also unsure if the experiment should include adjusting the grinder with several samples of frozen beans to achieve the expected output/time relationship. So I cannot say it increases TDS. I can say, it appears to increase pull time and the need to grind coarser.

This has been my experience as well. Grinding beans frozen vs room temp requires a grinder adjustment finer when using the room temp beans if one wants the exact flow rate. So something is clearly different in terms of partical size/distribution, but I think it needs to be looked at under a microscope to really understand what is going on. Then we can debate which is "better".

Nuova Simonelli is way ahead of ya here, this is what the Clima Pro grinder does with its heated burrs. (Mythos One)

nuketopia wrote: Not sure why the pre-frozen beans pulled at such a different rate. But it did. Unfortunately, to really validate all of this would require multiple samples, which I didn't have time to accomplish. Also unsure if the experiment should include adjusting the grinder with several samples of frozen beans to achieve the expected output/time relationship. So I cannot say it increases TDS. I can say, it appears to increase pull time and the need to grind coarser.

https://baristahustle.com/grinder-paper-explained/

According to this study, the theory is that the beans shatter rather than tear which creates more fines. It makes perfect sense.

In Perger's latest blog post he also advocates for other benefits of freezing. He seems to be building the case that bean straight from rested state to freezer until grinding is the freshest and highest TDS method.

https://baristahustle.com/2017-predictions-promises/

sluflyer06 wrote:Nuova Simonelli is way ahead of ya here, this is what the Clima Pro grinder does with its heated burrs. (Mythos One)

The Mythos One will both heat and/or cool the burrs, but the desired goal is to have a consistent temperature that doesn't fluctuate throught the day in a cafe.