It's really funny to me to just how much junk information there is in the coffee world and just how strongly people believe it. Even here on hackernews it seems. This is the exact sort of 'fact' that sounds good, and makes you feel like you know what you're talking about.

I'm a roaster. All coffee is sorted by size, or at least all quality coffee. It's necessary, not only for an even roast, but it's also an inherent part of green coffee processing. You have to screen and sort the beans to dry them.

The reason grocery coffee is bad is simple. They roast it until the oils come out and then the oils go rancid because it has been sitting on the shelf for the last 6 months getting to you. Even if it hasn't gone rancid (way more common than you'd guess), it's still stale and overroasted. Americans expect coffee to be dark, bitter, and cheap... And so that's what they get. But what you said isn't true. Even the crappiest bulk market roaster/reseller roasts by size and the blends after. They literally don't have a choice.

To be fair, a lot of the junk info comes from roasters keen on delineating themselves in any way in a saturated market. Taking words that are true for everyone and making them seem unique to your business is a sales tactic ad old as time.

https://espressocoffeeguide.com/gourmet-coffee/arabian-and-a...

I will back you up. I visited a coffee plantation in Guatemala and they said they sort all of their beans by size before selling them. I asked if people paid different prices, but they said no. The reason was that the roasters want consistent sizes.

And this was just some small coffee plantation.

Small plantations are more likely to be selling high quality beans, for which buyers pay a premium. (It's similar with cocoa beans.) So their high-end buyers/roasters may be accustomed to consistent bean size in a way that large-scale, low-margin purchasers are not.

Hello! Coffee enthusiast here. I'd like to follow-up on this statement:

> They roast it until the oils come out and then the oils go rancid because it has been sitting on the shelf for the last 6 months getting to you.

Are you saying that it's bad if my coffee beans are glistening with oil? I usually took that to be an indicator of freshness. Or do you mean that if they're no longer glistening that the bag is probably stale?

FWIW, most of what I buy (except for the Costco bag that I take to work) has a roasting date on the back so that I can guarantee a certain degree of freshness.

Light to medium roasts won't extract oils to the surface and IMO have a much nicer flavor, especially when using good beans.

To me a dark roast Ethiopian tastes the same as a dark roast Costa Rican. They taste very different with a lighter roast. You lose the bean's uniqueness when you go darker which is one of the reasons cheap coffee tends to be dark.

I feel like I am the only one but I find that "uniqueness" - sour/fruity taste disgusting and can't stand the lighter roasts.

I prefer a dark roast with heavy cream :)

You’re not alone. There are dozens of us!

> Are you saying that it's bad if my coffee beans are glistening with oil?

It isn't inherently bad, but it's usually a sign of more mass produced coffee. It's easier to roast coffee like that because it all tastes pretty much the same which is good if you need to make the same coffee for thousands of different locations. And some people enjoy the carbonic taste of coffee like that.

More lightly roasted coffees will have big differences in flavour that's not really possible to control for on a mass scale I don't think. Especially between origins and varieties.

it’s a sign that it’s a dark roast, which many mass produced coffees are. The third wave has tried to instill a culture of “nothing darker than a city roast” which I think has been harmful, as it marginalizes all dark roasts as cheap roasts, which isn’t the case.

That said, I think dark roasts age much less gracefully than a medium roast due to the oxygen exposure of oils, but I really love a full city roast for espresso.

Oils start sweating out of the bean when you get closer to really dark roasts. You'll see a lot of Starbucks beans glisten.

Lighter roasts will never be shiny like that because they haven't been roasted long enough for the oils to react like that.

Always grind your beans just before you brew. Never buy preground coffee.

Oil exposed to air can start to go bad after a month or so exposed to oxygen. So if your coffee beans have visible oil, they’ll be slightly more likely to taste worse sooner, just because the oil’s right there on the surface. But it doesn’t necessarily mean anything negative otherwise. If it helps, think of it like butter: you can reasonably leave a stick of butter on the counter for a while, and then it doesn’t taste as good anymore. Coffee is the same way, oil or not :)

Dark roast is a little like well-done steak; you're mostly tasting the effects of the heat, not the quality of the ingredient. Good beans will make good dark-roast, but okay beans will probably taste pretty similar. The lighter roasts let the differences shine.

Thus, trendy 3rd wave coffee is almost universally light to medium roast. So oils might get a bad association this way, but that's not really fair. It's just a dark roast. It's the age and original quality that really matters.

>I usually took that to be an indicator of freshness.

I've only heard it described as a flaw. None of the recently and well-roasted beans from the local roasters I visit sell oily beans. But Starbucks? Or typical grocery coffee? Usually always dark and oily.

Surface oils are not an indicator of quality either way. The roasting process brings oils to the surface, so darker roasts tend to have more surface oils. From what I understand, the oils appear a few days after roasting, and then dry out/reabsorb after a few weeks.

Mostly how I see it too. I roast my own and I like it quite dark. I stop roasting when the first bit of oil appears and sprinkle water on to slow things down. The oil keeps coming out until the heat leaves, so getting the heat out of it is my objective. Stir and a little water, and wait until it cools about to touch. The oil doesn’t seem to keep coming out after the heat has left.

It's not even like sorting by size would be difficult. All you need is a sieve-like machine with different size holes & hoppers for each. Or a sluice-box, or one of many other ways to accomplish this. If it made a huge difference in quality, and it was not hard to do- everyone would be doing it. And indeed, they are.

WRT junk info, coffee is not that different from audiophiles or wine. Luxury product, real differences exist, but they are subtle & hard to measure. Most of the experience is subjective.

Mostly true, but unlike high end audio, the best coffee can be bought by most people. The best I’ve ever had was $2US.

High end audio isn't expensive, the bullshit is.

You can grab some nice drivers, unreasonably high-quality crossover components, and couple sheets of MDF to make yourself some floor-standers for a few hundred. Using any number of popular DIY speaker designs, you'll have something that would easily stand up to anything of a similar format in a blind A/B test.

Amplification is dirt cheap now; class-D amps are superlatively good even in the <$100 category. You can even add in DSP for a very reasonable price if you want to jerk off to glass-flat charts.

Building your own is not the same as buying, though. What would the cost for that same product be if it came all assembled for you, but the same quality? I'm betting it's pretty expensive.

It's probably also not that expensive to roast your own coffee beans, but it's an extra step that non-hobbyists don't want to deal with.

The best coffee maker you had was $2 or the best coffee was a cup you bought for $2? If the latter, I'm sure the equipment and training that went into that was in the thousands of dollars range.

> Most of the experience is subjective.

Followed closely by...

> The best I’ve ever had was $2US.

QED

I am also a coffee roaster. Everything this person says is true.

The better groceries in my area (Whole Foods, Harris Teater, Publix) carry locally roasted beans with their roast dates on them.

Who's talking grocery stores? Coffee shops that roast, do it any way they want. And sure enough some do it badly.

> ..."you can have strong coffee without having burned coffee"

just noting that when people say strong coffee, they usually mean "more caffeine", not "darker roast". and coffee people generally know that darker roasts have less caffeine.

i actually like darker roast too, when i want a caramelly coffee (by adding cream and sugar). my theory is that not only does a dark roast better hide lower quality beans, but starbucks knows that most people put cream and sugar in their coffee and darker roasts are better for that, which is why it's so popular.

but when i want straight brewed coffee, i seem to prefer a medium roast.

Darker roasts having less caffeine is another bit of folk wisdom that actually turns out not to be true.

https://www.kickinghorsecoffee.com/en/blog/caffeine-myths-da...

interesting! the weight vs volume point is something that's not obvious on first blush.

Not what I mean. More coffee flavor. Without tasted scorched.

Generally the beans are roughly the same size, and what you called burned, I believe is simply because it's roasted darker to compensate for the less than ideal quality of the beans.

The fact that WBC finalists are using coffee that the roaster haven't sorted based in size tells a lot. Perhaps the farmer does it to some degree.

>The fact that WBC finalists are using coffee that the roaster haven't sorted based in size tells a lot. Perhaps the farmer does it to some degree.

I'm not sure if you've looked at espresso chemical papers (mostly the Illy ones), but they're pretty cool and they might explain this.

The oil extraction curves are non-linear. Lighter roasts that aren't at risk of burning smaller beans can be paired with variable bean size to produce a spectrum of related flavour notes, providing a bit of depth to a varietal that has a very strong and pronounced (but limited) set of notes.

I haven't, but it sounds like something I'd enjoy. Thanks for the pointers.

Try it before judging! Its definitely a burned taste, and once its gone you would not believe the difference.

I simply cannot explain why they wouldn't do it if it made a difference. A machine that sorts the beans by size is cheaper than the machine that package the coffee, so if it would make a better product, I'm sure the big roasters would do it. It's not like they cannot make great coffee. They can make coffee that's world class, but the market will not pay that much.

But regardless, I have tried coffee that isn't burned. I primarily use lighter roasted beans, and there is zero burned taste.

I wonder if that's more to do with the grade of beans than roaster-sorting.

Edit: also, could this be related to inconsistent grind? Smaller bits over-extracted.

You may as well find value in looking up “density sorted” coffee, where they concentrate the high-density beans for roasting to max our flavor per cup.