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Comment by AdmiralAsshat | Hacker News Reader

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.

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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.

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