Reusing yesterday’s coffee grounds for another cup of coffee
wokelark.com
wokelark.com
This post took more effort than 99% of blogposts, calling it blogspam is pretty offensive.
It reminds me of another favorite article online: https://www.instructables.com/The-Science-of-Biscuits/
Sourced from: https://travisdanielbow.weebly.com/blog/category/cooking-exp...
Turns out the espresso machine is already set up to stop extracting just at the point where all the good flavours have been removed. (Also reason to be thankful that the good flavours happen to extract first)
Those variables were:
- coffee/water ratio
- grind size and consistency
- water temperature
- extraction duration
But there is a fifth element that should be observed that is the water hardness. Having too much or too little magnesium and calcium disolved in the water may result in wildly different cups of coffee. Yes, that is leaning more towards the pedantic side, but if you live in a region with extremely soft water, you have to fix water hardness because it is essential to dissolving coffee compounds in it.
Water hardness graph: https://jgagneastro.files.wordpress.com/2018/12/water_coffee...
I would suggest reading How to make the best coffee at home, from James Hoffmann.
>Furthermore, the type of water you use also plays a vital role in the process of coffee extraction.
>You can learn more about the best water for coffee making, by clicking here.
Interesting graph, but I was missing some explanation. Here's the figure text, from [1]:
"Water properties for various recipes, cities and bottles. The dashed line represents a 1:1 relation, and color lines correspond to different recommended ranges.
In the figure above, you can see the range recommended by the SCA (green bar), the region recommended by the Colonna-Dashwood & Hendon (2015) Water for Coffee book (this mythical book is now pretty much impossible to find, but it is said by the ancient ones to go much deeper in the chemistry of coffee extraction than what I could ever write in this blog post), and the more constrained region recommended by the Specialty Coffee Association of Europe (SCAE), which is mainly based on avoiding regions of significant scaling (upper right) or corrosion (upper left), two aspects that are mostly important to the delicate internal parts of espresso machines."
[1]: https://coffeeadastra.com/2018/12/16/water-for-coffee-extrac...
Even overpriced Starbucks at $10/12oz (~$13/lb) means that each mug of coffee is still only costing me around $0.35.
I'll brew with fresh grounds, thanks. You can _always_ add water if you want warm brown caffeinated water.
You will find that this gets you most of the way to great coffee.
I had this guy, and it lasted about 5 years. But you can do DIY pourover with similar results, electric or stovetop tea kettle + carafe with pourover:
https://www.amazon.com/gp/product/B076VVTRNM
Keep it simple, and good coffee is cheap. No need to re-use grounds.
I do have one use case for grounds re-use: If I want something hot to drink in the afternoon. I have good tolerance for caffeine (I have never become physically dependent), but I just have to keep caffeine consumption to before 3pm, or I might have a hard time sleeping. A re-run of the morning's grounds (usually 3 scoops of grounds), gives me coffee flavor, but without too much caffeine.
> Buy a coffee maker where no hot water touches plastic. Just glass and steel.
> ... gets you most of the way to great coffee.
James Hoffman, who's credentials include winning the "World Barista Championship", publishing multiple coffee books, running a coffee roasting company, and so on, has significantly different advice.
When experimentally comparing the glass, plastic, and ceramic V60s, he found that the plastic was easier to preheat and sucked less heat out of the grounds, resulting in better brews (https://youtu.be/1oB1oDrDkHM?t=480).
What reasoning do you have for avoiding plastic? How can it change the brew other than through its thermal properties (which are pretty clearly beneficial compared to glass and steel, right?)
He also recommends getting grinding beans very shortly before brewing.
I personally can easily taste the difference between freshly ground and stale grinds, and can notice the difference in extraction and flavor from varying grind size, so I'm personally quite dubious of your claims. I have yet to ever make "great coffee" from pre-ground beans bought from the super-market, only mediocre coffee.
Can you not taste any different between fresh grinds and pre-ground coffee? From fiddling with the grind size to find the right extraction for what you personally prefer?
What reasoning do you have for avoiding plastic?
Is there still any known issue? If they meant BPA, surely they could just say that?
https://pubs.acs.org/doi/10.1021/acs.est.9b02540
Note they studied mesh bags. Flat surfaces with less exposed area should have lower emission rates. Still not great.
Edit: apparently polypropylene does too. https://www.theguardian.com/environment/2020/oct/19/bottle-f...
Alright. Don't hesitate to share then. I can't give away my one sugar... would love options to swap with.
Also just not eating sugar makes you more sensitive over the smaller amount of sugar food contains anyways.
BSF are fascinating, they prevent deadly pathogens reduce the volume of organic waste quickly and actually produce insect frass more nutrient dense than worm castings. Amazing little creatures!
I am sorry, but I have to disagree. The stilted, repetitive, one sentence per paragraph style is so obtrusive and so reminiscent of blog spam that I could not focus on the content.
At the end of the day, all the author does is re-brew a cup of coffee with used grounds. Who has not tried that at least once (and went blegh and never tried it again)? To me, the article is as content-free as it is hard to read.
You disagree that they enjoyed the article?
But I still can't help but wonder out of sheer curiosity, to take this to the limit -- what about making cold brew but with 3x or even 5x or 10x the normal ratio of grounds to water?
Surely there's a way to get "reused" coffee to a comparable concentration to "first use". And then... would it be even remotely drinkable, or too much bitterness-to-flavor? Sufficiently caffeinated, or would comparable caffeine make it unbearably bitter?
I'm so curious now -- I feel like this blog post got 80% of the way, but is missing the final experiment!
https://en.m.wikipedia.org/wiki/Ristretto
Intensely flavourful IIRC.
The parent is on the right track if they want to get a strong and storable coffee. Overdose a cold brew, and dilute (or not) and microwave for a hot drink.
My batches of french press last 2 days, so in this way I suppose I am reusing the grounds.
https://en.m.wikipedia.org/wiki/Placebo#Mechanisms
Maybe there is something akin to belief in the belief, i.e. "I'm not religious but will pray for god or whomever in dire situations". The mind is a weird thing and truth is, we don't have a good understanting of what's going on with the placebo effect.
With my grinder, a 12 second grind gives a good first cup. For the second cup I keep the spent grounds in the filter and add another 6 second grind. If I go for 3, another 6 second grind.
That works out to a 25% or 33% savings depending on number of cups (18/24 seconds vs 24/36). I've never tried carrying them over day to day.
Considering how expensive and wasteful paper coffee filters can get, it's a nice optimization.
If you want to minimise waste, get an aeropress. Stick with the paper filters and use a soft clean toothbrush to clean the filter. You’ll notice that if you use the aeropress as a pour over, the draw down rate will stay consistently fast. The filters are much smaller and are good for at least 5 uses.
Would you mind sharing the model of metal filter that you use? I've been looking for a good one for my Chemex, but I haven't been able to find any decent comparison reviews. If yours has lasted 3 years that sounds like a buy to me!
The grinder processes beans at what seems to be a pretty constant beans/second flow rate, and through trial and error I figured out that "X beans/second * 12 seconds = Y volume of ground coffee" makes a cup of coffee that I like.
I've never bothered to figure out what "Y" actually equals, and the flow rate seems to stay constant enough that 12 seconds always works out to a good cup.
I do have a few related thoughts on some different points in the article.
> The ideal extraction yield for coffee is between 18% and 22%. An under-extraction of 15% or over-extraction of 25% will cause an imbalance in the components and will result in either acidic or a bitter-sweet coffee drink.
The lower bound of the range is accurate, but the upper bound is outdated. People like Scott Rao and the folks at Barista Hustle have been involved in expereriments to push extractions even higher than that; if I recall correctly, I think they've reached just shy of 30% while improving the taste of the resulting coffee. The key is that bitter flavors don't simply start extracting past 22%, but that above 22%, the _evenness_ of extraction becomes very important. This is the point where factors like the grind size distribution (from the specific combination of beans, grinder machine, and burrs) and technique (e.g. your method of hand pouring to avoid fine particles from clogging the filter) really start to matter. Bitterness can even occur at 18% extraction if the grind size distribution is very uneven.
Another related detail the author mentions is that the second and third re-brews result in more watery cups. This is partly because fines (the tiniest particles) in suspension are major contributors to the texture of the coffee beverage, especially for espresso. Once you've extracted most of them in the first brew, there won't be much left for repeated brews.
My angle on this is that this is not a useful technique unless you're intentionally trying to ration coffee. If your repeated brews seem to extract some additional good flavor, you may want to explore ways to increase the extraction from the first brew instead.
On a related note, there is an old invention that essentially constantly rebrews coffee: the percolator.
And for as much as I like tea, coffee is irreplaceable.
https://www.youtube.com/watch?v=39g6utADRzs
They're awful.
Cold brewed coffee also lasts much longer before going into "tastes like old coffee"-territory, you can have it in the fridge for weeks while hot brewed coffee can taste bad after a few hours already. It is said that the acids in the bean play a role in this, and those acids are not extracted during cold brewing.
There is people experimenting with ultrasonic extraction processes as well.
I’ve tried this by re-using grounds, but also adding fresh grounds on top. (About half as much as i’d normally use.) It still comes out a bit watery, but much closer to normal.
> These are attracted by the wet grounds and it’s possible that the microorganisms start establishing their colonies in less than 24 hours.
> Therefore drinking coffee that’s made from yesterday’s grounds could be potentially dangerous while also having an unpleasant taste.
Storing the spent grounds in the fridge would be a good preservation method.
Personally, I think putting boiling water in the grounds as an initial treatment should kill off any initial bacteria.
Fungal spores aren’t killed by boiling, but they might germinate after soaking and then get killed after the second hit. This was an early method of killing fungal spores before pressure vessels: tyndallisation.
Coffee grounds (without any sugar, etc.) isn’t a very nutritive media.
But I agree that it should be fine if you put it in the fridge.
Sure, refrigerating them and keeping them in an airtight container would slow that but why risk it when all the good flavours of the coffee are already extracted?
My BS alarm went off for this article but turns out its accurate: https://happyearthtea.com/blogs/tea-101-about-tea/can-caffei...
They stopped when they had enough money to use fresh grounds daily. If it wasn't inferior, I'm not sure they would have stopped.
Simple syrup is incredibly easy to make and dissolves readily in cold coffee. I often make myself a small afternoon iced coffee from my leftover morning carafe, and a bottle of simple I made for cocktails is handy for that.
2 parts sugar to one part water, heat the water until the sugar is dissolved then bottle it.
That being said the veggies are often fairly tasty. The hat is they won’t nurture a next gallon of broth but without further dilution they are great.
James Hoffmann has a video on this topic https://www.youtube.com/watch?v=VV68NiRulEk
> And is all of this worth it? I personally don’t think so.
Author put some thought into it so it’s an interesting read, but still, the lede should not have been buried.
For me the diminishing potency is perfect as I don't want full strength coffee after 9 or 10 am so it's 0erfect and it saves me a bunch of coin.
Cold brew is not just refrigerated coffee. That would be “iced coffee”.
Cold brew is made in the fridge with new grounds (no hot water involved).
>I guess this backs that up a bit :)
No it absolutely doesn't.
Betteridge's law of Headlines strikes again