Can anyone please tell how to judge when my persian limes are ready to pick? Are there tell tale signs or standards to go by? Thanks for the input....
You can pick them once they are at a mature size. Limes are sold unripe in the stores, as a ripe lime is yellow not green.
The State of Florida's "official" maturity standard for limes is a minimum 1.75 inches diameter at the equator, or 42% juice by volume. But bigger is better, up until they begin to turn yellow, at which point the flavor changes, in my opinion for the worse -- it develops a rather flowery off-taste. So you want them while still bright green.
MM, are all limes yellow when ripe, or just the Persian? Thanks, Toni
Toni -- depends on what you call a "lime," a word without any officially defined limits. So 'Rangpur' "lime" becomes reddish-orange, but it is not at all closely related to the 'Key' or 'Tahiti' lime. Certainly 'Key' and 'Tahiti' turn yellow.
I've mentioned this before, but I'll do it again here, for clarity. 'Key', 'Mexican', 'West Indian', and 'Indian' lime are all exactly the same fruit. It just depends on where in the world you are, what you'll call it. This is the true Citrus aurantifolia.
Also, "Persian" is a marketer's word, never used by growers. 'Tahiti' is the variety name for this lime, and it is also more commonly known in California as 'Bearss' lime (pronounced beers). This one has also at times been called C. aurantifolia (Swingle placed it there), even though it is obviously a triploid hybrid. Tanaka gave it its own specific epithet -- C. latifolia. But since it is surely not a true species, it is probably best named simply C. x 'Tahiti' or C. x 'Bearss'.
'Bearss' lemon is entirely unrelated to the above, being a true lemon (C. limon) grown in Florida! In this case, pronounce the word like bares but with a hissed (not voiced) s at the end.
I should also add that we use the term "ripe" differently for citrus fruits than for, say, apples and bananas. Those fruits start out green and hard, with a lot of stored starch, and then, over a period of hours or at most a few days, convert much of that starch to sugars, change color from green to something else, and the cells soften, so a hard, crunchy fruit, becomes soft. That process is "ripening" in the true, physiological sense.
Citrus does none of those things. Rather, over a period of months, it very slowly converts acids (mostly citric) to sugars (about 1/2 sucrose, 1/4 glucose, and 1/4 fructose, in the case of oranges). They do soften somewhat, but not in the sense that a banana would. There is never significant starch present. And the color change in citrus occurs only on the surface of the peel -- the interior always was its final color.
Therefore, there is never a moment in time when a citrus fruit is "ripe." Rather, there will be a fairly long period in which it is good to eat, and perhaps a later time when it is even better. With oranges, mandarins and grapefruit, under Florida law, "maturity" is measured as brix (percent sugar), acid, and the ratio of the two, as well as juice content. When a fruit's test numbers reach certain levels, it is declared "mature." Once picked, most citrus do not continue to improve off the tree; indeed they tend to degrade in flavor. The one exception I know of is South African Clementines, which do increase their brix content and lower their acid content, slightly, after harvest, while on the ships to Europe.
In the case of the acid citrus (lemons and limes), they don't even get around to converting most of their acids to sugars. Instead, they may (in the case of 'Tahiti') develop odd, undesired off-flavors, when the peel color changes.
So, generally, 'Key' limes are eaten when yellow, but 'Tahiti' limes are eaten while still dark green, for the best flavor.
I'm truly amazed. This has to be one of the best posts ever. I wish they had "sticky" posts as this could very well be the best and most concise piece of info I've read on limes (and lemons).
It's too bad they don't have that feature where moderators can make "Fruit FAQs" about each citrus. Maybe I missed something.
Your statement above that "the color change in citrus occurs only on the surface of the peel -- the interior always was its final color" is so not the case in my experience that I wonder if I'm misconstruing that remark, or if it was qualified in some way that I overlooked. To be certain, I just sliced through a mandarin that is approximately five months old. The peel is dark green of course, and the flesh is a pale greenish yellow. When mature the interior of these fruits is a typical reddish orange mandarin color. What am I missing? Thank you for any clarification.
True, there is some intensification of color, but no change in the base color. In the case of pigmented grapefruit, they're generally brighter red before maturity than later. I suppose if you go all the way back to 1/2" fruits, there would be little or no color inside, since there are no developed juice vescicles. But what I mean is, by the time there are significant juice vescicles differentiated and growing, they are already developing their final color. Everything in a citrus fruit except the peel surface color occurs slowly and continuouly, over months of time, rather than the 3-day ripen-up that a banana, avocado, etc., would do.
Kudos to MalcomManners. The first and most recent post (in this thread) about the ripening and "readiness" of citrus fruit is better described than I have read anywhere. I second the motion to have these added to the forum FAQ. Having operated a nursery for several years, I can attest to the fact that questions about the ripening of citrus are among the most popular list of inquirees among citrus hobbyists. Bravo and thank you.
My lemon/lime tree has green fruit,looks like a lime,is yellow inside and taste like a lemon??? did it cross polinate with a meyer lemon or is it a lemon tree? The tag is not on my tree. Its about 4 yrs old, as is a meyer lemon tree in same area. When should we pick our first crop????