Why do my nopales taste so lemony? Because I pick them early in the morning...

My nopales always seem to taste amazingly fresh and lemony.



Here are some I picked this morning, and they were wonderfully lemon flavoured.



But most of what I've read about them describes them as not tasting of very much, or maybe a hint of lemon. I've been struggling to find ways to serve them so that the lemon flavour complements the rest of the dish instead of competing with it.

And then I stumbled on this...



It turns out that during the day, the plant closes all its stomata breathing holes up to conserve water. Then during the night it opens them up and captures as much as possible of the C02 that enters the plant in the form of malic acid (found in many fruits, and first found in apple juice, hence the name). Then during daylight hours the C02 is released so that the plant can use it to photosynthesize.

The wikipedia entry on cacti explains it like this -

Like other succulent plants, most cacti employ a special mechanism called "crassulacean acid metabolism" (CAM) as part of photosynthesis. Transpiration, during which carbon dioxide enters the plant and water escapes, does not take place during the day at the same time as photosynthesis, but instead occurs at night. The plant stores the carbon dioxide it takes in as malic acid, retaining it until daylight returns, and only then using it in photosynthesis. Because transpiration takes place during the cooler, more humid night hours, water loss is significantly reduced.

So now, of course, I have to remember to conserve enough energy so I can pick another nopale this evening as the light fades so I can do a taste comparison.

Then I can re-think all my recipes. Again...

Well I can confirm that nopales picked in the evening, from the same plant that gave me super lemony ones this morning, taste pleasantly fresh with just a hint of lemon. Which should be much better for a lot of the dishes I want to use them in!

I cut the nopale in half, and put half of that in a bowl in the fridge exposed to air, to see if it re-lemonified overnight.



I put the other half of that half in a bowl in some water to see if the water stopped it re-lemonifying. Only it floats so maybe enough air will get in to allow the acid to build up anyway. I tried covering it with a bit of plastic but suspect some air will still get in.

And the other half of the nopale I boiled up to kill it and then rinsed if off and stuck that in yet another bowl in the fridge too.



There's also a bowl with the left-over nopale that I cooked from the super-lemony one I picked this morning.

I will attempt another taste test in the morning and try to keep my head together long enough to write it up coherently.

OK, results so far...

Picked in the morning, eaten fresh - very lemony
Picked in the morning, cooked - very lemony
Picked in the morning, cooked, eaten next day - very lemony

Picked in the evening, eaten fresh - hint of lemon
Picked in the evening, cooked - hint of lemon
Picked in the evening, cooked, eaten next day - hint of lemon

Picked in the evening, chopped, stored in fridge overnight - stronger hint of lemon
Picked in the evening, chopped, stored in water (ok, but it floated...) in fridge overnight - stronger hint of lemon

Might still have to test submerging an entire pad under water so it can't take air in. It's also possible that being in the fridge slowed the reaction down so maybe I should test leaving them at room temperature overnight, which I'm guessing will make them very lemony by morning, but who knows without testing...

Also I should try freezing them to see if that changes anything.

Picked in the evening, cooked, eaten next day - hint of lemon

Picked in the evening, chopped, stored in fridge overnight - stronger hint of lemon
Picked in the evening, chopped, stored in water (ok, but it floated...) in fridge overnight - stronger hint of lemon

Picked in the evening, cooked, eaten 48 hours later- hint of lemon

Picked in the evening, chopped, stored in fridge for 48 hours - quite lemony!
Picked in the evening, chopped, stored in water (ok, but it floated...) for 48 hours - quite lemony!

Which suggests to me that the fridge slows down the reaction that the plant uses to capture CO2 and store it as malic acid, but doesn't stop it. Cooking does stop it!

That particular experiment is over as I ate them all for lunch. I promised to pick a couple of pads and prepare them for my son's weekend meals though. And I think he's going to be provided with them as prepped but entire pads, submerged in water with something to weight them down. He won't mind.  He likes experimenting. I think...