A number of people have observed that warming the beans above room temperature using a microwave or sous vide techniques also increases extraction. I suspect that a different process is at work in those cases versus elevated extraction yields observed when using beans that were ground frozen.

It could be that the elevated temperature makes the beans more brittle, thus causing more fines to be generated during grinding, or it could be that the heat facilitates extraction by drawing out certain compounds or giving them a head start. Or both. Or maybe other mechanisms are at work.

The bottom line is that It seems there may be more than one way to skin the cat -- or get more out of light roasts.

While TDS and extraction yield may be useful for determining concentration and extraction efficiency, they don't tell you much about flavor beyond strength and relative sour-bitter balance. The real test is to evaluate flavor differences between extractions of the same beans when ground frozen, at room temperature and warmed. The results could vary considerably from one coffee/roast to another.

I'm always skeptical of absolute pronouncements when it comes to espresso.

Yes I know what the end goal is, but if that was the only case they could easily have set the burr heater to only heat up to about 80F (above normal indoor temperatures enough to stabilize), instead they have it setup to sit at 95F which is well above room temperature.

mike guy wrote: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.

I think what he's saying is "Grind frozen. Then warm". I could be wrong, but that's what I understood from his post. Microwaving post grind would be easier to increase temp than sous vide, but how positively or negatively it would affect tds, and of course flavor, I have no idea.

nuketopia wrote:
unsure if the experiment should include adjusting the grinder with several samples of frozen beans to achieve the expected output/time relationship.

I think this is the most important part of your experiment. And this is what I would expect...When you get your grind adjusted to pull your "frozen" shot to the same output in the same time, I would expect the tds to go DOWN slightly. But until you adjust your grind to mimic the "nonfrozen" shot in output and time, you're really only looking at what happens with a finer grind.

Just to throw in another variable, but I imagine the temperature of the grinds will also impact the brew water temperature in the puck. So you're dealing with differences in particle size and distribution and brew temperature. Lots going on.

Actually, the Mythos Clima Pro heats the throat of the *burr chamber*, where the beans feed in, rather than the burrs themselves. By the time coffee enters the grind chamber, the beans are warmed up. The system will apply heat or fans to keep the temperature of the grind chamber throat between 30-40c.

I've know about Clima Pro for some time, which prompted my experiments.

The temperature of the beans when ground seems to alter their characteristics when brewed. I don't know if changing the temperature of the puck after grinding would have similar results or not. Would be interesting, but presumably, once flooded with hot water, they'll take on the water temperature.

I'll have to try the experiments with frozen beans along with adjusting to achieve a pull time consistent with room temperature beans and see what is happening. I of course, don't have a laser particulant scanner to play with.

mike guy wrote: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.

I meant something more like Remove From Freezer -> Grind -> Sous Vide -> Brew.

Some research has been done around the difference in grinds temperature to water temperature and how that contributes to TDS/EY. The idea being that less energy/water temperature is wasted on getting the puck temperature to an equilibrium during brew.

Peppersass wrote: While TDS and extraction yield may be useful for determining concentration and extraction efficiency, they don't tell you much about flavor beyond strength and relative sour-bitter balance. The real test is to evaluate flavor differences between extractions of the same beans when ground frozen, at room temperature and warmed. The results could vary considerably from one coffee/roast to another.

I'm always skeptical of absolute pronouncements when it comes to espresso.

I'd rather not get into this kind of a argument.

There are absolutes, in that they are measurable, repeatable phenomena. The instrument makes an absolute measurement and applying good laboratory practices and data gathering renders that into a scientifically valid process.

There are subjectives, in the sense that humans perceive things like flavors and smells. These are not absolutes because they are not measurable nor repeatable in a concrete way. While we can do statistical evaluations as to how a population responds to some change in a quantifiable parameter, the entirety of the population will not respond the same way. In a lot of cases, even the same subjects under the most controlled conditions may respond in a statistically-significant and different way.

The same sort of issue exists in other fields, like colorimetry. We can measure the spectrum and intensity of light quite precisely from say, an apparatus that people can then look into and decide whether two colors match or not. From that, we can derive in a statistical manner, a model of color vision. (in fact, this is how the science of colorimetry came about). We can stimulate human eyes with precisely metered wavelengths and intensities of light, but how those are perceived by any individual can only be statistically estimated based on data derived from a large sample of people.

We have the same issue with foods, smells and flavors, like espresso. We can measure and control the parameters used to brew and use instruments to quantify the results. That's just good science.

The second part of the test is how people react to the measurable changes. People often react to non-existant "changes" and fail to react to clearly measurable changes in all kinds of things, from visual to auditory to smells and tastes and even simple phenomena like temperatures. You can A/B people and ask them to discern Coke from Pepsi and they'll get it wrong. You can even do little tricks like put the same thing in both glasses and they'll express clear preferences for one or the other, simply by the suggestion of them being different.

Using instruments helps us avoid "voodoo" things, like putting a TICE Clock on our espresso machines. Instead, we can use science to make analytical changes and then decide whether these improve the experience of consuming the beverage.

nuketopia wrote:I'd rather not get into this kind of a argument.

I agree! But in light of the countless arguments that start much like the above exchange, I'm going to proactively discourage it by putting this thread on cooldown. I ask that contributors to this thread consider this admonishment in the Guidelines for productive online discussion:

HB wrote:Encourage positive, shared discourse. Be mindful of participant reactions and consider the tone of your replies; ideally they should encourage positive discourse. Conversely, don't be disruptive by dominating the conversation. Dogmatic or repetitive replies are rarely welcome.

Thanks.

I'm not trying to start a fight.

Think of tools like a refractometer like the thermostat vs. your wife.

Wife: "It's freezing in here tonight!"
Husband: "I checked the thermostat, it's set at 68-degrees like always."
Wife: "It can't be, it is freezing, turn it up!!!"
The very next night:
Wife: "It is burning up in here!"
Husband: "I checked the thermostat, it's set at 68-degrees like always."
Wife: "It can't be, its sweltering, turn it down!!!"
...

So the instrument is telling you the truth, with absolute accuracy and certainty and your wife is still too cold or too hot.

Coffee is like that.