> The freefall of grapefruit from 10 m does not damage the pulp[1] because pomelo peel consists of vascular bundles and an open-pored cellular structure with the struts made of parenchymatic cells.
I have a Marsh grapefruit tree, fruiting now (southern hemisphere) as it happens, and I note that it produces particularly pithy progeny. (Ignoring for the moment that Pomelo is one of the parents of the modern grapefruit.)
I don't have a convenient 10 metre drop to test this, and while I have no reason to doubt the veracity of this citation, I'm now consumed with curiosity why this plant has evolved to have this feature.
I expect it's quite an expensive adaptation, and given that modern specimens are the result of a lot of cross-breeding over the years to have juicier pulp and a lower ratio of skin/pith to pulp (ie. reduced resistance to damage) it presumably was even more expensive in ancestor plants.
Standard fruit purpose is to have animals unwittingly propagate the plant -- entice something to eat the fruit, and some time / distance later, deposit the seeds in a fertiliser ball. How does protecting the pulp from these kind of damage assist with that -- unless ancestor trees were spectacularly tall, and ancestor consumers fantastically fastidious on fruit quality.
While researching a reply, I uncovered USDA Technical Bulletin No. 1413: "Thermal Properties and Heat Transfer Characteristics of Marsh Grapefruit". Please enjoy:
It's not clear why this matters from the paper, in that it sounds like (but not spelled out) that they are perhaps trying to refrigerate fruit for transport, where the transport itself is not actively refrigerated, merely insulated, so the reduction to target temperature has to occur before shipping. However this was published in 1970, and I'd assume in that part of the world refrigerated shipping and (large) storage was not uncommon?
Aside #1 - undamaged grapefruit will happily store at room temperature for 6 weeks or more, and be the tastier for it.
Aside #2 - received wisdom is that grapefruit, and perhaps most citrus, benefit from one or more frosts to 'sweeten up', though I have never understood the mechanisms for this claim, or how high-water fruit does not burst its vesicles and then deteriorate rapidly.
TFA and this paper you cited may speak to the latter (the fruit content does not freeze overnight as the thermal inertia is so high), and might partially debunk the former.
(absorbed by osmosis during my time at Zest, a JIT produce handling company)
Harvest time is extremely hectic. There's a very small window to get months worth of produce picked, sorted, cooled, packed and shipped. Cooling is a major bottleneck, because capital for refrigeration is not unlimited. Likewise any delay can be a major issue- if a truck is slow to load, how do you know whether or not you need to re-cool your produce first?
It's well known what temperatures produce does well at (can't be too hot or too cold without MAJORLY affecting end margins) because it's easy to test by setting a fridge to a given temperature. It's much harder to know, for a given type of produce, how fast it will cool or heat, and how long you need to spend doing that. It's not as simple as sticking a thermometer in it, which will create paths for heat to move into and out of the produce. Even then you still don't know what the heat distribution inside the produce is so you can optimize the temperature over as much of the plant as possible.
It's really quite tricky and stuff like this helps farmers a lot. IMO farmers do more actual number math more than almost any other occupation (ex: [1]). Much of it is rules of thumb and guesstimation, but they still are constantly balancing dozens of figures to make choices every day. They're always doing mental calculations in economics, biology and physics. Even if the job wasn't so physically and technically taxing, I would respect the hell out of them just because of the mental workload.
And here am I the doofus who works in Accounting Software often saying "I should have done something with fruit" when my work involves too much math for my liking.
I heard (no refernece, sorry) that oranges do from green to orange when the temperature drops. Apparently colour change does not affect taste, nor necessarily indicate ripeness. Would anyone knowledgeable please chip in and correct or elaborate on this please.
"Eschew flamebait. Don't introduce flamewar topics unless you have something genuinely new to say. Avoid unrelated controversies and generic tangents."
Thanks dang, I understand and appreciate you pointing this out. However, I would say the original flamebait and a tangent was mention and praise of a person who has committed well documented genocide. So I don't see why my comment is the only one being flagged for pointing this out.
Partly it's a judgment call. I would say that bringing Churchill into a thread about English writing style (which was already off topic, but not a flamewar) does not count as flamebait, while bringing in genocide does. I can see how someone would argue it the other way.
Mostly, though, it's a matter of the effect on the thread. The value of a comment is the expected value of the subthread it spawns [1]. In this particular community a "Churchill+genocide" comment is pretty well guaranteed to spawn a flamewar, which was not true of the subthread one level up. So it's relative to the community you're participating in.
It's just tedious virtue signalling, rather than a contribution to the thread. We all know he did things that are considered abhorrent when viewed against the current, moral zeitgeist.
Sure, let's just starve your family to death and then laugh about it and see if you only consider it "abhorrent when viewed against the current, moral zeitgeist". It's amazing how people will not only downvote, but flag the posts here that go even a teensy bit against their propped up beliefs. And I thought the hn crowd was supposed to be discerning.
What does literary ability have to do with anything else a person has done? Would Macbeth or Pride and Prejudice have been worse books if they were written by Hitler for example?
Even though you yourself can judge a book only by its contents, when discussing it you will inevitably run into people who will bring the merits of the author into the discussion. It's called "The death of the author", and I invite you to look up the excellent videos covering the topic on YouTube.
>It's called "The death of the author", and I invite you to look up the excellent videos covering the topic on YouTube
I'd rather invite them to read the original Roland Barthe's essay (1967), which has that same title. Additionally, one can read New Criticism's authors on what they called the "intentional fallacy".
I personally wouldn't spend my time skimming through clickbait-y YouTube videos in hopes that I find one that is actually informative instead of a half-assed presentation made to maximize monetization.
Absolutely. I also have a pomelo tree, though it's still in a pot in the shadehouse, and produces a single (enormous) fruit each year.
Grapefruit are a cross, probably, of pomelo and a sweet orange - as you say, not all that long ago. While some grapefruit varieties are quite pithy, pomelos (that I've seen) are very pithy - hence the 'this can only have been even more expensive a protective layer in earlier versions of this plant'.
The question still stands - why is this adaptation useful, given it's probably expensive. (That assumption of mine may be entirely wrong.)
Early species would have been shorter, and all species in the history of this would have fruited long before the individual trees reached 10 metres (I'm guessing even in ideal conditions that implies 10+ years growth). Most would-be consumers of the fruit would be able to reach fruit within the first metre or so (if unable to climb or fly) and anywhere in the tree otherwise.
Interesting. There are other fruit & seeds out there that develop strong exocarp or mesocarp (think coconut) and I believe it has to do with wanting the fruit to travel longer distances to encourage geographic spread. The plant probably "prefers" that the seedlings take hold some distance from the parent, so wants the seed preserved longer and taken away by certain kinds of animals (hairless apes!)
What kind of animals live, or lived, in wild citrus' native range? Now I'm curious. [EDIT: Himalayan foothills... Macaques? Elephants?]
Or it's selected for particular animals as spreaders? In wild grapes, for example, most are adapted for bird spread (small dark acidic berry, high up in a tree on dangling shoots) but there are a handful of species (vitis labrusca "fox grape" for example, and vitis rotundifolia aka muscadines) that have adapted for mammals and they are quite different: larger berry, lighter colours, strong smell (think Concord), lower acids, slip skin, and a tendency to "shell" (fall off the vine when ripe). They also tend to grow wild in shadier moister areas, e.g. the underbrush where foxes and skunks and racoons etc. will grab them, not birds.
All I'm finding is 'south east Asia' as origin -- which is an enormous range of fauna.
I understand the 'travel far and wide', though of course evolution's not directed, and is there significant difference in fitness & success over the long term for a variation that allows a plant to produce offspring 1km away in one generation (say 5y), rather than taking 2 generations?
(And, of course, it's worse than that. The 10m drop potential isn't realised until the plant is probably 15 years old or more -- at which point the distance / propagation calculation is almost irrelevant, as that specimen would have produced fruit for at least 5 years whose seeds would have travelled the same distances, regardless of this (future) robustness capability.)
Sadly, though, I suspect plant archaeologists have more pressing concerns than this question.
Note to grapefruit tossers: Please practice safe science. If you're going to throw an object 10 meters straight up in the air and see how it impacts the ground, you need to not be the ground it impacts, or at the very least your science will be ruined, if not your day as well.
I have a Marsh grapefruit tree, fruiting now (southern hemisphere) as it happens, and I note that it produces particularly pithy progeny. (Ignoring for the moment that Pomelo is one of the parents of the modern grapefruit.)
I don't have a convenient 10 metre drop to test this, and while I have no reason to doubt the veracity of this citation, I'm now consumed with curiosity why this plant has evolved to have this feature.
I expect it's quite an expensive adaptation, and given that modern specimens are the result of a lot of cross-breeding over the years to have juicier pulp and a lower ratio of skin/pith to pulp (ie. reduced resistance to damage) it presumably was even more expensive in ancestor plants.
Standard fruit purpose is to have animals unwittingly propagate the plant -- entice something to eat the fruit, and some time / distance later, deposit the seeds in a fertiliser ball. How does protecting the pulp from these kind of damage assist with that -- unless ancestor trees were spectacularly tall, and ancestor consumers fantastically fastidious on fruit quality.
[1] https://doi.org/10.1088%2F1748-3190%2F11%2F4%2F045002