I just wanted to take a moment on the blog here to really expand at length where I get the numbers and times I state with (some) confidence in discussing lifespan.
I've always been super curious about coffees' "freshness" lifespan, because it seems pretty subjective and seems a very contentious thing in rarified coffee circles.
I mean, we've all seen best-by dates claiming months on end, and we've all got that coffee-snob bud who wants you to believe all worthy coffee is 'dead' by six days old. They're probably not both right, at the very least.
To me, that hyper-shortened lifespan seems sold like The Emperors New ______; where if my beans or your beans or their beans are purported to last longer - "well, they couldn't have been that good anyway". But it's similarly clear that some folks are really overstating the lifespan of their products and are relying on an underinformed or apathetic consumer to 'get away with' their claims.
So I set out to test this thing out a little. I used my apartment kitchen, my mum's dinner parties, foot traffic at the plant and customers caught unawares ... essentially, I was forcing many little cups of coffee at anyone who'd come within a serving trays' reach of me.
With a self-reported survey of 'coffee acumen' - priming question was "Speaking broadly, how knowledgeable or dedicated would you say your relationship with coffee is?" most people came back with some variation of "not very knowledgeable, very dedicated", even from people I would have scored 'higher' on knowledge. However, I feel I do have enough total pool to have a decent representation of 'average consumers,' 'average specialty coffee consumers' and 'highly coffee-passionate consumers' or 'experts.'
I "ran" three groups, like I was doing Real Science or something. All three groups got the same range of samples: five cups of the same product at one-week lifespan intervals. The first group was told we were QA-ing separate, similar, components for an end blend, and they should report what they think of each for individual quality. The second group was told we were assessing potential purchases, and they should rank by preference in order, and note any 'jumps' or 'drops' in quality between samples. The third was told we were assessing lifespan, and they should tell us which samples they found staleness present in. This group was sampled a very fresh sample and a very (two months) stale sample to calibrate their palates.
The first two groups came out with remarkably parallel results. For the coffee I'd used on that round, most subjects from either group were scoring weeks 2-4 quite high and descending in order, then week 1 slightly lower, and week five as an 'very poor' outlier. I think a safe conclusion to pull here is that folks preferred weeks 2-4 relatively interchangeably and found notable decline in the fifth week.
The group primed to check samples for freshness or 'look for' staleness found staleness much earlier. They generally reported decline from the three-week old sample onward, with some outlier participants even scoring some staleness in the two-week-old sample. I think a safe conclusion to pull from this group is that some staleness can be detected at three weeks from most consumers.
But what gets most interesting is when we combine what our three groups have told us and see how that works loose. If you're actively looking for staleness, you're more likely to find it earlier in 'younger' samples than when you're not looking for it. This could be a reasonable explanation why some companies swear by seven days while others will quote thirty-five - a difference in approach, values, and sampling methods can return very different results. Weeks three and four scored quite highly (above the one-week) sample when subjects were assessing quality, but staleness was consistently reported at those same ages from the staleness-primed group. This could be a reasonable hint that staling starts fairly early but being perceptible while subjects are looking for it doesn't mean that same 'amount' of staleness negatively impacts overall enjoyment until much later.
I'd like to note that I worked very hard to control for levels of coffee knowledge and aptitude across groups. Highly coffee literate subjects, 'experts' if you will, were not more or less susceptible to the priming effects described in the difference between groups 1 & 2 and group 3. They generally had fairly similar quality or preferential rankings to more 'lay' consumers, while those participating in group 3 would note staleness slightly earlier - but I don't have enough data to say for sure that one's not stat noise.
Running follow-up tests to see how groups play out across different kinds of coffee and roast profiles is a much bigger task, and one that's sort of a long-term project. So far it looks like different beans have different trends, all within the expected "it starts tasting boring some time between three weeks and five, by five its almost always done" with no huge trends across roast level and/or origin.
In both cases, I do not have a 'clean' enough experimental setup or a large enough body of data to draw any truely academic-grade conclusions. I might have enough to feel comfortable speculating and suggesting, but that's my own interpretations and results so far are not solid enough data to escape the potential influence of opinion.
Because the third group needed to be 'calibrated' with a earlier service (two additional cups served prior to the core five) it was more challenging to fit folks into our schedule, or tests into theirs - I did end up with a sample group about 2/3s the size of the other two.
I'm seeing a lot of hype around the fourth wave recently. Some corners of this industry want to believe they're almost there, or want you to believe they're so ahead of the curve they get a whole new increment.
I'd like to convince you they're jumping the gun.
Thing is, for all that there's a lot of people very excited to herald or declare or discover "the fourth wave" - most of those people are using things unrelated to how waves one, two, and three were decided and demarcated. Most of these are, ultimately, self-serving at best and downright misleading at worst. I don't want to vaguely throw shade, but I also don't want to provide directed calling-out, I just want to prompt a chat about whether labelling anything "fourth wave" is really useful.
Speaking generally, "waves" define the consumers' relationship with coffee as a product - not business models, roasting style, hardware setup, or how much moustache is permitted or required on your baristas. The term was coined by coffee historian Timothy Castle to describe the cultural growth of "craft" coffee in North America, and the term caught on with the industry.
Each eave represents a relatively fundamental change in the relationship between product and consumer.
The first wave occurred ~1900 and describes the adoption of coffee into the American lifestyle en-masse. This is Folgers' era, the time when everyone served Folgers and everyone else claimed to. Coffee wasn't good, wasn't even really particularly differentiated, and generally awful by modern standards. But they didn't care - drinking coffee was American, and if that was what coffee was like, they'd enjoy it that way.
Second wave is the era of Starbucks', but started long before Starbucks did, in the 1960s or so when substantial brand differentiation entered the domestic market and "going out for coffee" was adopted into culture just as ubiquitously as coffee itself was 60 or so years prior. The rise of the cafe brought into style "Italian-style" coffees, and thus the espresso bar, the chain cafe ... Coffee was recognized as having quality and taste differences, and the public developed preferences.
Third wave is ... now, plus probably another 30 or so years. Coffee as an artisanal luxury product, something bearing consideration similar to wine, or existing in a culture of connoisseurship. People are exploring and developing the "craft" associated, the over the top people have way over the top ways to explore their fascination; the average consumer has clear and well-understood preferences that span multiple brands, and has the awareness to select something they believe they will like from a range of unfamiliar brands.
But put simply, the three waves are just the labels for each era in the fairly easily trisected history of coffee in North America, with lines drawn based on how the average consumer saw their coffee.
Hopefully you're able to immediately and easily recognize that these are not unanimous collective shifts - they're a matter of 'average' values and I'm sure most coffee professionals can bring to mind one or two first wave consumers and a whole lot of customers that fit far better into second wave values than third - even if they themselves identify as a "third wave" establishment. For most coffee businesses, the bulk of customers are coming from second wave values rather than third. In short, we haven't finished the third wave yet, we're still starting it. From "inside" the specialty coffee community it can be relatively easy to fall for the echo chamber and buy into "we're done with the third wave, it's time to move on!", there's a sense of impatience that there must be something to move on to, some new movement or identity to define this or that aspect of what we do that we don't feel fits into traditional goals.
Waves, in their historical non-marketing-buzzword sense, are incredibly useful to the two big "coffee things" I do.
As product dev & QA for Pistol & Burnes, having a set of categories I can roughly buttonhole consumers' values from makes planning stock and offerings ... if not easy, easier. I can aim segments of the coffee we make at second-wave consumers because we value their business and they are the biggest coffee-consuming demographic we have access to. We can similarly target coffee at third wave consumers, understanding that that needs to be marketed and sold differently to a very different audience.
As a mod and member of /r/coffee, coffee evangelism, or more specifically third-wave evangelism, is a huge part of what we do. Most of the people who come to our community are, at first, second-wave consumers. Understanding their approach and their values as they relate to coffee is fundamental to persuading them to stick around long enough to be converted. "Third-wave coffee has something for you, it's delicious and it doesn't demand that you enjoy hyper-light roasts off a V60 at 184.7°F, it's not about facial hair or espresso or $12 cups of coffee - it's just about doing coffee better, and we can do something that's 'better' by your standards." And waves are a really great model for explaining how and why their values differ from ours, as well. For instance, understanding that a typical second-wave consumer both enjoys and has pride and affection vested in their morning cuppa is important - too often the third wave uses inherently judgemental language in telling second wave consumers about the benefits of upgrading and in doing so alienates someone who wanted to become a convert.
From the business side, though, from the inside: your "wave" isn't about you, it's about the type of customer you're attempting to cater and appeal to. Speaking very broadly and generally, a second wave cafe is appealing much more as a "cafe" and a "cafe experience" than it is on the basis of the coffee they serve. Similarly broadly, the third wave cafe is appealing based on it's scope of offerings and performed dedication to quality. If there aren't fourth-wave customers, you can cater to them all you want but it's probably not going to be a successful business.
The most fundamental value of The Third Wave is that of conoisseurship - the idea that coffee is something to be appreciated and enjoyed, with clear quality and experiential differences existing between different origins, brew methods, and serving styles. There is depth of enjoyment and preference to be explored, always room for improvement, and "quality" serves as an ultimate abstract goal.
Sound familiar? This is how pretty much everyone in the modern coffee industry thinks. We may not all agree, we may not like sharing a label with this or that business we don't consider "up to muster" but we're all still trying to do coffee better at the end of the day. It doesn't matter if this is shifting to batch brew over pourover, or trying to get portion packed coffee out of the terrible rep its earned, or trying for fully automated brewing to better focus on raw customer experience ... It's still rooted in the core value of "there is space to improve this".
To become a "Fourth Wave" establishment requires catering to a consumer value set that abandons connoisseurship entirely - without "backsliding" into either first or second wave values - you still have to be going somewhere new, but it has to be new enough that you're leaving a focus on notions of quality or excellence behind.
But as long as you're trying to provide a better something - experience, coffee, etc - you're still doing third wave stuff. The third wave is defined by a culture of conoisseurship, and as long as practices play into that, nothing has changed. And that's not bad. Third wave is good. Wine is *still* in its third wave, and has been for 200 years or so. There's nothing wrong with a focus on providing and seeking subjective quality. And that is the focus that has to change before we're moving on to a fourth wave. To transition into a fourth wave, we need a fundamental relationship shift between consumers and product on the scale of "america started drinking coffee" or "america realized there is more to good coffee than having a preferred brand". In short, consumers need to stop caring about quality entirely.
...And the only way that's likely to happen is if quality is something we're able to take for granted. Once the average consumer is confident that they don't need to seek quality intentionally, because *all* coffee is quality coffee, then we're ready for a shift in consumer relationships big enough to herald a fourth wave. Not before.
Once each and every question of "quality" is solved, when there's nothing more to learn or explore - sure, we can move on to a fourth wave. But how does a connoisseur leave behind connoisseurship - without backsliding? Coffee growing needs to be so good, so known and plotted, that there are no "bad" coffees coming to market - each coffee is equivalently excellent, and differences in terroir and processing are only relevant to personal preference, not quality. Roasting needs to be similarly solved - the optimal way to roast any given bean needs to become a known quantity, the difference between how I roast a bean and how you roast a bean needs to result in solely preferential differences, not quality. Purchasing needs to have lost its guesswork, labels are honest and straightforward, consumers understand them, and everyone can be unquestioningly confident that they will receive what the bag claims. Brewing, too, must be in a sort of ideal state; there's no opportunity cost in swapping hardware or method, achieving a perfect brew is so trivial that selecting a method is again simple preference, not practice and expertise.
In short, the connoisseur hangs up his hat when his expertise is no longer needed. The fourth wave can happen when all of the magic, the adventure, the learning, and the challenge has gone out of coffee - solely leaving behind the delicious.
Second week as "A Coffee Roaster" and I guess I've done my first batch?
I don't want to take too much credit, mostly I just twiddled knobs and pressed buttons at the times Sobbuh asked - but I'll take what I can get and I was providing input, so for all that it was a roast-by-numbers job, I did "do the roast" by all standards except actual knowledge or creativity.
Most of my roasting experience was, to be frank, adjusting the fan up by three points once every minute. ~Thrilling~.
Though to be fair, it's much more interesting from a theory perspective than an actual implementation one. The goal being to create a small but growing "heat debt" in the drum that allowed our rate of rise to gradually drop without spiking post-first crack, allowing a gentler - and always decreasing - curve without baking or drying the beans we're roasting.
This is a common one, and a question I often struggle to answer - it's hard to give the best answer without sounding like I'm being a smartass. "Pretty much everywhere" sure sounds like I'm giving sass, but it is genuinely the best answer I have.
We buy coffees from almost everwhere in the world that grows coffee, and the one region we don't buy from (Asia) is not an intentional choice or preference so much as just not finding a coffee from there we're excited to serve.
Our coffees hail from South & Central Americas, Southeast Asia, and Africa. For blended products we typically mix and match multiple contintent or region origins rather than coffees from the same general area; for instance our popular Spitfire currently contains Sumatra, Peru, and East Timor. Each contributes something very different to the end goal of the blended product; the Sumatra brings smoky spicyness, the Pperu some nuttiness and toasted sugars, and the Timor brings a hearty body and the deeper woodsmoke notes that compliment the Sumatra's spice.
All of our blended products note the origins they're made of on their webstore page and we offer many of those as single origins as well; if there's an origin we use that's not listed but you want to buy feel free to get in touch - we can probably set aside a bag for you when we roast next.
Our roastmaster moved on to greener & brighter pastures at the start of the month, and Sobbuh is handling most of our production while I'm equal measures heavy labour and roaster's apprentice.
I've got a whole bunch of the theory under my belt - but it's a little like driving a car, say - having the theory alone isn't quite enough to do a good job. We've adopted a Sunday/Wednesday main production schedule so we can tune freshness to be ideal relative to when we're actually shipping those coffees.
And despite the steep learning curve and the sudden change in responsibilities, we're crazy stoked about tightening the loop between QA, consumer relations, and actually producing the great coffee our business is all about.
Since the very start of my dalliance with coffee, caffeine content has been the one question that comes up most consistently. It's also the question whose answer has changed the most frequently in that same span of time. "We" keep learning new things - here's where we're at now.
It doesn't really matter.
Kind of a boring answer, yeah? Probably why all the myths are more fun to share.
However, the details are more interesting. Dark roasts contain more caffeine as a percentage of the bean's total mass. Light roast contains more total caffeine. The difference in caffeine quantities between the two, however, are negligible - using slightly more or less coffee (a slightly higher heap on your scoop, the margin of error on your scale) has a far greater impact on caffeine quantities in your beverage than roast level selections.
For a long time, it was understood that dark roasts have less caffeine because it "cooks off" during roasting - this is both true and completely wrong, in the fun way that questions with detail-intense answers can be. Some caffeine is lost during the roasting process, but caffeine is stable at all typical roasting temperatures - even this study, that remorselessly over-roasted beans in the name of science, found only 5.4% of total caffeine lost during those most severe of conditions. The caffeine that is lost is mostly taken via the moisture loss - caffeine may be stable at those temperatures, but it is water soluble at all temperatures and some would be lost that way.
Some more interesting information, if you're particularly keen on your buzz ...
Caffeine is water soluble, as mentioned above, it's actually one of the most "accessible" compounds in your coffee, and will extract nearly completely almost immediately. Once your coffeemaker has been brewing for between 30 seconds and a minute, depending on your grind size, your pot has all the caffeine it's going to get. The taste will continue to change as it navigates your extraction profile, but the caffeine is fixed relatively early.
"low quality" coffees will often contain more caffeine than high-end ones. Most craft roasters don't use Robusta varieties outside of espresso blends because it's often not as tasty as Arabicas, but the Robusta beans do contain noticeably more coffee than their Arabica counterparts. Many low end producers will pad Arabica blends with less expensive (and more caffeinated!) Robusta beans. (We don't; we also don't use any in our espresso at the moment.)
It's genuinely pretty hard to measure caffeine content, and certainly not possible at home or your local cafe. From the study I linked above, the researchers needed to use "HPLC" or high-performance liquid chromatography to separate and measure each component of the solution. This is a pretty complex and very expensive (~$20,000+) machine, so there's not a commonplace practice to measure or check.
We work really hard to make decisions ethical towards all of: the environment, the producers, the nation of origin, and coffee in general as a product and as a community or industry.
Our coffees are puchased from collectives or farms who share our values regarding protection or care for the environment and natural ecosystem they're growing in, respect and fair pay for labourers, while we are paying a fair price for the coffee we buy. Many co-ops are networks of farms who all collectively self-monitor out of an interest in not devaluing something they use as a sales point to buyers like us. Others work with external monitoring groups or NGOs.
However, our coffees won't always come to us certified by familiar large "ethics" organizations.
For instance, Fairtrade Brand. We can't sell coffee as "Fair Trade" - the term is legally protected - unless the beans themseves were from a Fairtrade branded lot from a Fairtrade certified farm or collective.
At each stage of that process getting green beans off trees and to us for roasting, the certification costs money. Many of the co-ops we deal with simply cannot afford that certification, no matter how ethical their practices are. And many more might be able to afford the cert, but do not see themselves gaining anything from membership.
The Fair Trade certification guarantees certain prices - a base minimum that's currently $1.40 per pound of green or $0.20 above market rate, whichever is greater. Current price as of today, June 3 2015 is $1.63, FT price would be $1.83; the cheapest coffee we have in stock today is ~$2.75, most are above $3.00. While some of this goes to a middleman, our farmers still receive much more than the FT-mandated price for the coffee we're buying from them.
It gets more complicated from there. Sorry.
Fairtrade sets maximum quotes on the amount of coffee they will buy and sell as "Fair Trade"; there is less world market demand for fair trade branded coffee than producers involved in the program - membership is limited in some regions, and not all coffee bought by Fairtrade can be sold at full price with the branding, meaning not all certified farmers are necessarily receiving the "guaranteed" rate for their coffee despite their participation. Even if they could all afford membership, our non-Fairtrade farmers would not necessarily be allowed to join - nor would they necessarily see things improve compared to remaining independent or uncertified.
Because of price controls and mandatory middle-man sales, many high-quality farmers (like, for instance, the ones we buy from) would take a loss joining, as they would be unable to seek competitive pricing on a superior harvest. In order to maintain their coffee's certification, farmers are contractually obliged to sell to a specific middleman in their region in order to maintain the certification's chain of custody.
Monitoring is an uncomfortable and generally messy business: Fairtrade has been criticized in the past for poor monitoring of the specific things they claim to address, and this is true with most Developed-World imposed ethics organizations across multiple industries - there is very little way to say with certainty that the locals don't just put on a good show when the monitors are in town, and year-round monitoring is unfeasible. ...Not to mention patronizing. We find it culturally uncomfortable to impose an external observer to monitor externally-defined "ethical standards" as opposed to trusting the self-interest and values of both individual co-op members and different co-ops.
For the bulk of the farms and coops we buy from, what we might call "ethical standards" is simply part of doing business right, and monitoring or policing takes place from within and out of a genuine belief in the importance of treating the coffee, the land, and their workers "well" in a way that is fluid and flexible to the realities of their craft. The coop will simply bar a member who is cheating the system under the understanding that their actions are directly harmful to both their community at large and to all other producers in the region if left unsanctioned.
Ethics as they relate to coffee are messy. At the end of the day, we simply have to take someone at their word when they tell us coffee is ethical, whether it's Fairtrade, a local coop, or a distributor or middleman. We believe that intrinsic motivation to "do right" is a stronger incentive to uphold the ethics claimed than a price minimum and the occasional imported western observer, so we don't necessarily prioritize purchasing Fairtrade or similar certified coffees over coops we trust and products that are particularly great.
While I'm not normally partial to the Metric/Imperial debates that seem to exist South, or even online - often the hassle of swapping from a familiar to a less so system of measures is going to cost more effort than a more efficient system might gain - within coffee is one field where the use of metric measures is so much easier that I will still advocate it.
Quite simply, if you have a scale that can do Metric, you don't need to understand or have an intuitive grasp of it; much less conversions or translations between. And using metric while brewing coffee is so particularly simple that it's worth prioritizing a scale that at least has a metric option.
Using metric weights and fluid measures (grams and millilitres, respectively) for beans and water makes for very easy brewing math, because the two convert 1:1, a millilitre of water is by definition the volume that makes up one gram. When someone gives you a brew ratio of 1:17, metric is fairly easy to scale. Multiply both sides by the amount of coffee to be used, (For 20 grams beans: 20x1=20g coffee, 17x20=340ml water) or divide your water by 17. Even if you're more familiar with Imperial measures, the intuitive scalability of 0.71 solid ounces of coffee per .574 fluid ounces or .84 cups of water doesn't translate as elegantly as "1:17."
When I'm asked to recommend grinders, I have a "trifecta" of offerings I bring up: the Capresso Infinity, the Bodum Bistro Burr, and the Baratza Encore. We sell the last mentioned, the Encore. They all come in at relative price parity $150-200 CAN, and all offer relatively similar performance.
However, there are a number of much cheaper burr grinders that exist in between cheap-o whirlyblade grinders and the ~150$ trifecta offerings. These mid-range or super-budget burr grinders largely go unmentioned and ignored in coffee communities, and maybe why is never quite explained clearly enough.
Here goes my attempt.
The biggest factor in a grinder's "performance point" is overall particle consistency. Connected to that are the nature of the motor or drive, and lastly to a fairly small degree, heat retention.
Particle size, though, particle size is king.
As background, sorry if this is stuff you know: The amount of time it takes to ideally extract any given morsel of coffee is a factor of the ratio between it's surface area and its volume. As the exposed surface rises and contained volume falls, the particle will extract progressively faster - the water doesn't have to travel as far or penetrate as much bean-structure to "unlock" the tasty bit. However, there's a downside - each particle also contains some flavour parts that are undesirable, and once the water has taken all the good stuff, it just keep taking more even when only the bad stuff remains.
If your grinder is putting our particles all approximately the same size, your entire brew mass will take the same amount of time to extract ideally - each particle will unlock and extract at approximately the same rate, because the surface area : volume ratio will be similar. However, there's no grinder in existence that actually produces entirely one size chunk. And variance in grinders isn't as modal as might be desirable either, generally it's a bimodal curve with the "target" particle size being the larger, and a second peak at a substantially finer size (imaginatively dubbed "fines" in coffee parlance). How much of your brew mass is fines has a exponentially increasing effect on your brews, especially across drip or pour-over preps; the fines extract much faster than your target particle does and will inevitably have fully overextracted by the time your target particles extract properly. The more of your total brew mass that is fines rather that target of course, the more represented that overextraction will be in your cup - I'm sure you can imagine how if 5% of your brew mass if fines, it would be much less noticeable than if 50% of your brew mass is fines. Smaller amounts are inevitable and have relatively negligible effect on the cup, while larger amounts have a sort of compounding effect.
Because fines will generally settle and be carried to the bottom of your brew (they won't retain air well enough to float, unlike most everything else in your cone), in sufficient numbers they can begin to slow your brew by clogging up both filter and brew mass, meaning that water has time in contact with both fines and target particles to extract - so not only will your fines definitely overextract, but your target particles may also begin to as well, because of how slowly the water is moving through your mass. (This is not the case with immersion brewing, but then again, for most of those options you end up getting fines in your teeth rather than your filter so harm is both more apparent and a more matter of preference.)
In simplest form, the most a grinder costs the more consistent it's particle size will be, and this stays fairly consistent until you start approaching $1000 models, at which point specialization, branding, and competition start factoring into cost in more impactful ways than the relatively marginal performance gains available.
The even-more complex details of particle size come down to burr configuration and motor. In both cases, our end desire is that beans are essentially repeatedly cut into increasingly small size pieces until they reach our target size. Because the beans are organic material and uneven in texture and just won't be nicely cut into even little pieces, even in this method some fines are still produced. Two other things can also happen in a burr grinder that produce far more fines: crumbling and shattering. If the burrs are dull, moving too slow, or not beveled right, beans will be crushed in between the burrs, but they will be crumbling into uneven pieces until the maximum particle size your minimum, and will produce a spectrum of fines below that point, as well as a few chunks that might be bigger but slipped through sideways. If your burrs are moving too fast, beans will be hit hard enough to shatter, rather than held in place and cut as burrs act against one another, this again creates many too-small particles as the bean shatters, and any pieces too large will be again shattered until they are all small enough to pass through.
So as far as the burrs themselves, many cheaper burrs will use more robust cutting faces to provide expected durability across a cheaper base material. Others will use a very "aggressive" bevel to provide longer-lasting perceived sharpness, similarly to save on a more expensive burr material. As far as motors, as best as I can tell (not an expert on electric motors as a topic) a motor suited to provide cutting is expensive or difficult to manufacturer. Either way, cheaper burrs seem to fall into one of two general failings - best generalized as too fast or too slow. These often match the above two "inferior" burr types, in order. One type is designed as slow moving, high-power drive with "crush" burrs to aim for a believably consistent pulverization. In others, they'll use an overly high drive with a moderately "aggressive" burr so that rotational momentum prevents jamming, allowing an overall cheaper motor, but with the side effect that the grinder is essentially relying on being able to shatter any beans it cannot cut. The first will generally produce more dust, but feel more robust and durable; the latter is dubiously "better" of the two but will sound and feel less robust and generally have a burr lifespan much shorter than the whole appliance lasts - or at least would, if they weren't prone to simply burning out after jamming up a few times.
In all cases, upgrading to a burr does produce some gains in terms of particle consistency over blade; the reason I'm particularly vocal about the entry level "Trifecta" being the Encore, the Bistro, and the Infinity ... roughly in that order is twofold: the more subjective "will you notice and enjoy the change?" gains obtained spending the extra 20-30 on a ~$50 burr don't directly match the investment, while spending the ~$160 on something like an Encore or other Trifecta will, for most people, provide a relatively immediately apparent change in the cup of coffee they're brewing. So at the core, I feel it's the most impactful "layer" of gear upgrade; so unless you're heading towards espresso, upgrades beyond a Trifecta grinder also become relatively marginal gains again. In most cases, I figure someone is very likely to want to upgrade to *at least* the performance point a Trifecta grinder offers, but may not necessarily want to upgrade *past* one of those options.
The super expensive stuff is generally characterized by increasingly marginal performance gains with the actual improvement taking increasing effort and precision to exploit during brewing. For instance, pushing boundaries of extraction values while avoiding the impact of fines on taste get harder and harder as the brew goes on and as extraction increases. Most people brew coffee at an extraction between 16-20% taken from the brew mass, because with most grinders the fines produced begin to have a perceptible impact on brew taste as extraction crosses above 20%. With exceptionally high end grinders, it can for instance be possible to reach 24% extraction before overextracted notes begin to be perceived, but that does of course take a brewing ritual that is able to control and adjust for all the other possible variables (time, water dose, evenness of extraction via technique, etc.) or the high-end results from the grinder are largely pointless; if they're high-siding their brew and only partially extracting the stuff left near the top and way overextracting the stuff near the bottom, even getting numerically perfect extraction and having the capacity to check that is meaningless, because the taste will still be impacted by the two extremes of extraction present in the cup in spite of removing the correct amount of mass from the grinds.
Lastly, heat retention: as the burrs pulverize beans, they grind against the beans and the beans grind against them and all that friction creates heat. And a bunch of it. This isn't a big deal if you're grinding a small-ish amount occasionally on a midrange grinder. But on something cheaper, the burrs and motor are entirely set up to prioritize meeting performance minimums, and no effort is necessarily made to make sure the burr can adequately shed heat over a long grind or a few sequential grinds. Any heat build up can be transferred back into your dry grounds as they pass through; heating the coffee before it hits water can seriously impact taste. For this reason, very low end grinders can often provide a relatively satisfying experience in the short run, but fall short if you're ever called on for more than one or two pots back to back.