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If you want to go for a over-the-top techy solution you could do non-destructive testing with a near-infrared handheld spectrometer. It's a pretty neat technique that can determine ripeness of a lot of fruits (and properties of other materials) if that can be detected via abundance of certain molecules.

It looks though that Consumer Physics stopped selling their SCiO device that was ~$250 to consumers, and I don't know if there is any equivalent current alternative.

That would be the best.

I already can't imagine going back to life before my infrared thermometer -- for food, for liquid temp, for pan temperature, for pan hotspots...

And similarly you can pry my sous vide circulator away from my cold dead hands.

If there was seriously something guaranteed to tell you ripeness, that would be golden. (Pineapples, mangoes, and melons like canteloupes, are sometimes tricky too -- I'm usually pretty good at figuring them out, but sometimes they surprise you.)

Lots of consumer cameras have near infrared sensitivity, mostly 750nm but with a long exposure I can get photographs through a 900nm filter in my Fuji X-Pro. You lose at least four stops.

Could the photography technique work to determine ripeness? Assuming the fruit is fairly motionless of course.

I have to admit I'm not the biggest expert on it. I mainly know about it because my brother wrote his PhD thesis about using portable Vis/NIR spectrometers as food checkers (verifying that they perform on par with expensive desktop spectrometers).

He showed me the SCiO in person a few times, and IIRC always had to make direct contact with the solid probe, so I'd be surprised if a NIR photograph would be a suitable substitute. I think it also mainly measures the area of the fruit where you make contact, so to get an optimal picture about the ripeness of a single fruit it's good to take multiple measurements. That also usually makes fruits with tick skins/shells (e.g. melons) hard to measure.

There seems to be a startup[0] aiming to bring suitable sensors to smartphones so that anyone has access to it - something that the food checker research literature has been hinting at for some time.

[0]: https://mantispectra.com

Thinking about it a little more, it might have some mileage. The IR spectrometer is just measuring the color of the avocado, albeit very precisely and under known lighting conditions.

One of the reasons photographers enjoy infrared photography¹ is because foliage shows up brilliant white against pitch black² skies³. Photosynthesis is inhibited by both green and IR light so plants are bright in IR for the same reason our eyes see it as green.

I absolutely think that you could get the same result with a flash photograph from a good modern camera and probably just using the green channel. One of the many things these cameras are designed to be good at is detecting minute subtleties in shades of green⁴.

I’m looking forward to trying it on the weekend.

―

1. Traditionally done with a monochromatic black and white film where only deep, bright reds gave the negative any density, rendering as brightness in a positive print. This is in contrast to “panchro” black and white where a bright object of any color would print as white.

2. Unlike blue light, the atmosphere disperses almost no infrared.

3. A good example of all of the above is here: https://fineartamerica.com/featured/infrared-willow-tree-stu...

4. Our eye’s sensitive to green is partly why digital cameras have twice as many green sensors as they do red and blue. It’s also why high fidelity inkjet printers use more shades of ink for printing photographs. (Epson printers use one yellow, two different cyans, and three different magentas.)

I press against the side and it mushes in slightly. this tells you the avocado is ripe or past ripe. When you cut it open, then if it's already browning, it's gone past ripe.

I agree it's a bit difficult but I used to make a few pounds of guacamole a day and it always worked great.

Squeeze the side of the avocado, and if it gives AT ALL it's ready to eat.

If it's soft it's way way overripened. Take a piece of cardboard between you fingers and squeeze - that's the firmness level that indicates the avocado is ready. Actually even more firm than the cardboard and the avocado is still ready.

> where you can sometimes feel the level of hardness/softness more accurately (if it is a particularly thin-skinned one), you bruise it

You are squeezing way too hard.

I think you’re underestimating the variability in hand strength between people.

Self-calibrating over time.

You just need to press it gently with all your fingers around the principal axis, not on the poles (as if your hand were a spider). If it feels hard, is not ready; if it feels soft, but not too soft, is ready. Also the color and the texture of the skin. Green means green, black and clear/bright + soft means ripe, black and opaque/wrinkled + too soft means overripe.

Source: I’m from Mexico.

You must be consistently getting the world's worst avocados - do you always buy them from the same store? Though it might just be a variety designed for distant shipping that sucks in general.

None of what you described sounds accurate to me but I'm spoiled in the Southwest. Ripe avocados are definitely soft and when I find the rare one that isn't, it's usually a bad avocado altogether (most of the flesh is very tough despite being overripe).

The avocados I buy look like this:

https://upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Av...

See how the outside is super bumpy, and there's a thick rigid brown layer before you get to the green flesh? Rock-hard skin even if the flesh is soft. A serrated knife helps to cut through it without smushing the flesh.

While I see other photos that look like this:

https://daily.jstor.org/wp-content/uploads/2017/05/avocado_1...

Where the skin is visibly much thinner and smoother and there's no brown layer, and I can only imagine that's the type of avocado where people can judge its ripeness. But those don't seem to be available in NYC at my local store or Whole Foods or anywhere...

There's an avocado delivery service in NYC that claims to deliver perfect avocados every time. There's some good press coverage around it: https://davocadoguy.net/

I use a similar service in New Zealand, and no longer have avocados ruined by overzealous squeezers in the supermarket.

I don't know who these people are, but they exist!

https://www.youtube.com/watch?v=38m-wnbHPLA

> Where the skin is visibly much thinner and smoother and there's no brown layer, and I can only imagine that's the type of avocado where people can judge its ripeness. But those don't seem to be available in NYC at my local store or Whole Foods or anywhere...

I get both of those here in SoCal, or at least a varieties that look similar to those photos - the bumpier variety is noticeable when I come across it (it's definitely tougher). I never paid attention to the thickness of the skin or kept track of how quality correlates to the bumpiness, though. I'll keep an eye out from now on.

I wonder if there's a single vendor/broker supplying the stores in your area. Have you tried buying them from outside the boroughs?

If its still hard there set it on the counter a day or two and check again. The test works for me with these sorts of avocados so I’m thinking user error.

Right but what I'm saying is it's always hard. Because the skin is so thick and hard there's literally no way to tell what the flesh is like underneath.

Except sometimes it's a little thinner/softer that you can actually press the outside, but you still have to use so much pressure it bruises the avocado. There's zero way of "gently" checking.

I've opened avocados that are still rock-hard on the outside, after waiting a full week, only to discover they're overripe and brown/gray on the inside.

And I have no problem with any other fruit or vegetable. Just avocados because of their crazy thick/hard rind where I live.

I just don't see how it can be "user error". My only suspicion is it's a different subvariety or grown for extra-thick skin for longer-distance transport or something.

you, sir, have a broken avocado

A durometer, acoustic impulse-response and special UV-VIS spectrophotometer are all instruments used to detect avocado ripeness and usually work well.

A durometer is the cheapest at about $40. If you're right that it's impossible to tell by hardness then it wouldn't work. But you might find that it's more sensitive than your fingers and so it can work?

I would be interested to know the result of a durometer test on your fruits because about 85% of consumers report firmness as a useful measure - a lot but certainly not everyone. So yes maybe there is some granularity to discover there: specific situations where firmness just doesn't work well?

I buy the same Hass avocados you posted, and I've lived in every region in the U.S. For the past 10 years, I have eaten an avocado (minimum 1/2 avocado) every single day. That is several thousand avocados.

I can say with absolute conviction that it isn't the rind giving you trouble. I can pick every ripe Hass avocado out of a bin of 50, and never once be wrong. That said, there are a couple of stores in my current area that have garbage Hass avocados. The ones I buy from this store are consistently gross and fibrous, even when ripe, and have a very short window. I boycott these stores. They either have a second rate supplier, or else somehow ruin the product in transport.

By the way, you need a gentle touch and the ability very slowly, smoothly increase pressure. You pick up the avocados that are not yet ripe, the moment one is on the threshold, such that there is a nearly imperceptible give which does not bounce back, you buy the avocado. It should not bruise the fruit, and you won't be able to detect it when peeled. After this check, you can visually tell when it has fully ripened, ~1-2 days later. For what it's worth, I've never successfully ripened one AFTER cutting into it, and I've never kept an uncut avocado for more than 4 days.

Thank you!

I think this is the most helpful comment -- first of all, I'm now just convinced that the stores I usually go to must be getting garbage avocados for whatever reason, I genuinely never guessed that would be a per-store thing. I'll try some different places, there must be different suppliers.

And I think:

> nearly imperceptible give which does not bounce back

Could be the key. I've always been looking for some pretty obvious give -- saying it's borderline impercetible seems like it might be the key. Other commenters here seem to be saying something similar.

Also good to hear the majority of people advising to feel the side or bottom (not the stem end as the article suggests).

I think there's hope for me yet! So thanks to you and everyone else who's been helping.

I’ve successfully judged the ripeness of those avocados by squeezing all my life

There's a stem of sorts at one end. Prod at it from the side - if it falls off easily, it's ripe or too far gone. If it stays attached, not ripe yet.

More usefully, you can buy pre-mashed avocado in the same style as pre-made guacamole. If the use case involves (or could be made to involve) mashed avocado this option has a serious shelf life (presumably it's irradiated or similar) and lives in the fridge until use time.

I'm following Rick Bayless' directions to check the _bottom_ of the avocado and use it or put it in the refrigerator (for 3-7 days) when it gives slightly.

https://www.rickbayless.com/ingredient/avocado-1/

I've mostly had good luck, but sometimes they're just bad to start with, bad because they're bruised from mishandling, or have been exposed to too much heat.

I don't see a lot of the tough leathery ones, but I have seen a few. (Seattle, so I'm not in the southwest.) I wonder if they are a different varietal or just dried out.

Not really sure why it's giving you so much grief. I gently press on the bottom larger side and if I feel it's soft and not hard or bouncy it's good. I press on the larger sider because in my experience it takes longer to ripen.

The period of time they taste appropriate is longer than the period of optimal softness. I eat 4/day (lowest carb source of potassium), and it was initially surprising how soon they tasted good.

Also, the longer and thinner the point at the tip of the avocado, the less random the brown spots are. I rely HEAVILY on this to avoid loss, since I buy them 24 at a time when I go to Costco.

I usually put the tip of my thumb and pinky together and then press the palm flesh beneath my thumb first to get a sort of muscle memory as to what I am looking for.

Then I press the avocado around the centre and compare. If it is around the same I open and eat. Seems to work most of the time — with the super thick skinned ones I generally press higher up on the avocado (closer to the stem)

> if it's ripe I try to eat the rest quickly

If it's ripe, put the rest in the fridge, and you'll have a week or two to eat them at your leisure.

Apply some sciencey thinking.

Test a variety of ideas (perhaps start with what is given here) until you find something that works for you.

Challenge yourself: either practice someone else's technique, or invent your own.

Outcome: satisfaction for the rest of your life every time you use your technique and get a perfect avo!

You know that Hass is German for “hate”?

I always find it funny that I didn’t bother to change the name here.

SF didn’t change the name of Haight Street either. People are pretty comfortable with homophones in general.