Bitter Zucchini

Very often I will add a Tblsp of butter to a saute pan, saute onions and garlic until soft. Then add chopped zucchini (half moons) and cook long enough to get slightly soft. Occasionally I'll toss in a little lemon. Salt and pepper to taste.

Sometimes the zucchini has a slight bitter taste and other times it doesn't. Any ideas why?

Also I SWEAR the zucchini often has a slight lavender aftertaste.....

[xiaobao12]

Do you guys deseed your zucchinis???? I've seen people do this but don't know if it's necessary.

I wonder if it's related to the bitterness problem? Thank you.

[Dwight]

This is the first time i ever tasted zucchini that was bitter, but today i tried the saute a garden grown zucchini plant and had a very bad taste experience. It may have been too young or a mutant. I hope it wont make me ill.

[harlick4]

Zucchini, along with many of its closely related relatives including cucumber, produces an intensely bitter group of compounds known as cucurbitacins. Wild type squashes are so bitter as to be almost inedible to humans and most animals. Some can even kill small animals. The squashes that we usually grow in the garden have been selected for low levels of these bitter compounds (a notable exception is bitter melon used in Asian cuisine where the bitterness is a prized part of the flavor.)
However, even carefully selected squash varieties will produce high levels of cucurbitacins when they are stressed by environmental factors such as too little water or too much heat. Larger squashes will have higher levels of the compounds than smaller fruit. Natural cross-pollination with wild gourds may also increase the bitterness of cultivated squashes.
Cucurbitacins are toxic at high levels, but they are so bitter that it is almost impossible for someone to consume enough of them to get sick. The worst that usually happens is an upset stomach for a few hours.
There is little that can be done to reduce the level of cucurbitacins once the plant has started to produce them. Unfortunately, they are not very soluble in water and are very stable to heat, so boiling the vegetables doesn’t do much good either. Anecdotal evidence suggests that cutting off the blossom end of the squash prior to cooking can reduce some of the bitterness. The best strategy is to water the plants carefully and harvest the squash earlier.
On the positive side, cucurbitacins attract certain kinds of beetles and may be useful for pest control by luring the beetles away from other plants. There is also some evidence that they can be used to treat a number of human diseases

[Claudette]

Harlick4, you make it sound as though salting won't work, and I had such hopes... I can't grow my own zukes any more (my backyard is the size of a Mini Cooper) and had quit eating zukes many years ago after encountering too many bitter store-bought ones.

[Cheese Boy]

Claudette, from past experience, I've found that it's best to avoid the zucchini with the deep solid green exterior because they are almost always guaranteed to be bitter. Your best bet is to seek out the yellow-green speckled variety of summer squash. We also know it as zucchini, but it's just another variation of the green summer squash. These are typically NOT bitter. I've included two pics where you can compare the two. Click on the images to enlarge.

[krisssy]

Thank you Cheese Boy. I did buy dark green zucchini instead of the light green speckled zucchini that I usually buy. It was my first time having bitter zucchini. I think that was the problem. I bought it, because it said organic. Thank you for your post.

[PBSF]

Thank you for your post. It is the only one on this thread that accurately explain that cucurbitacin is the cause of bitter squashes.

[Cheese Boy]

That reply deserves a gold star. Excellent and highly informative.

[rweel]

harlick4 - thank you so much for your thoughtful, thorough reply. I joined chowhound.com just to write you how much I appreciate you taking the time to explain what's wrong with the zucchini I buy at the end of this long, hot summer. Great advice!!

[harryharry]

Very interesting - I've only noticed baby squash with a bitter taste... in fact, I don't use them any longer -
same thing?

[itryalot]

Could it be the type of pan? I make something like Ina does; onion wilted and slightly browned in EVOO, add half moons of zucchini and sautee until crispy on outside yet not soggy. Add a sprinkling of parm regg at the end. Delish.
I had bitter zucchini once and could not get down to the reason. For some reason, it never happened again, but I leave the skin on and scrub the heck out of it because they can be slimy.

[chowmel]

Ages ago, an elderly neighbor told me that to get rid of the bitterness in cukes, zucchini, and other summer squash - you cut both ends off, then take the ends and rub them on the surface you cut them from - rub one end clockwise and one end counterclockwise. This will draw the bitterness out and into the ends - toss the ends .

I'm inclined to believe this may not work ; )

[itryalot]

I have done this with cukes too on the advice of my overly superstitious sister in law. I don't do it any longer; I found it made no difference.

[thew]

i don't know about the rubbing part, but i know with cukes and zukes the bitterness is usually in the ends. so i always cut a good chunk off each side before cooking or even peeling... dont want to drag the bitter across the veg

[jerry i h]

When I was kid, I grew these things in the backyard. I noticed that if you did not water them enough, the zucchini would get bitter and there is nothing you could do to fix it. Now, whether at home or at work, I always whack off a piece and taste. If it is bitter, I just chuck it or refuse to accept it. I am sorry this is not very helpful, but I am tired of unscrupulous vendors selling zucchini that they know is too bitter to eat.

[Kajikit]

Sometimes zucchini is bitter... I know - I hate it when it is! Luckily not every zucchini will be that way, only a few random ones, so before I cook one I cut a sliver off it and taste it to see if it's edible or only good for the bin.

[chocabot]

Do you peel you zucchini? Sometimes I find bitterness in the skin. You can either peel it entirely or in "stripes" to control bitterness.

[cheryl_h]

I agree with the recommendations to salt before cooking. Slice off a piece of the raw zucchini and eat it. Any bitterness should be apparent. If it is bitter, sprinkle the cut slices with salt and let stand for about 15-20 minutes in a colander. You'll get a fair amount of liquid coming off. Drain, rinse and dry well before cooking.

[Homero]

When I used to work at a little mom and pop italian market, the owner and head cook swore by salting the sliced and shredded zucchini to let it sweat out some of its liquid which she claimed was where the bitterness came from. Put the slices or shreds in a collander and sprinkle generously with kosher salt, then layer more zucchini, and repeat. Let it sweat it out for about a half an hour, then rinse well in cold water. I do that without a second though nowadays, so I'll have to do an experiment to see how well it really does work. Maybe its just my perception that it is less bitter when you sweat out some of the liquid.

We did the same thing for eggplants.

I've bitten into bitter portions of zucchini, broccoli, and other vegetables. Always thought it was an uneven application of pesticides!

[tashariff]

hi!

i broil them w/o garlic or onions and i find they ARE bitter no matter whether i salt them or not!!! i love them and am now frustrated i can't eat them. has anyone tried a salt and sugar mix?? help!

Did you store them next to some apples before you ate them? I suspect that vegetables can be affected by the over-ripening effect of being next to apples.

I have definitely had bitter zucchini, my impression is it's correlated with how long it's left on the vine-- the bigger the zucchini, the worse it is. Sounds like you had small ones, though. I know it was the zucchini because I usually don't put garlic in with mine. I've heard you can do the salt and rinse routine like for eggplant, but I've never tried it. I generally just saute it until it caramelizes a bit, and haven't noticed any bitterness.

The bitter may actually be from oversauteed garlic or from too high a heat. Garlic and onions cook very differently, with onions getting sweeter and garlic usually getting more bitter...

That's why you're not supposed to cook them together for any length of time. Try sauteing the garlic first and removing it just as it gets golden but before it gets bitter. Try tasting the garlic as you cook it to determine how the flavor changes as it progresses.

That's what you get for being a supertaster! :-)

Seriously though, I think I saw in Marcella Hazan or something like that that you should never saute onion and garlic because it can get bitter, although that seems like crazy talk to me.

Are you sure you're cuting enough of the ends off? I have that problem with zucchini as well. Cutting plenty off each end and coooking well usually solves the problem, although sometimes you just get a bad squash.

As for not sauteeing onions and garlic together...sounds like crazy talk to me too!

I lightly cooked, so maybe I need to cook it longer. I did notice that towards the end there were no 'seeds'. If I cut it all of, though, I'd not have much zucchini left - perhaps they were picked too early. I'll try sauteing longer next time - thanks!

I have almost stopped buying zucchini because of the bitter taste. I just cut up some to saute and thought I would taste it raw for the bitter taste and it was there. I have not always had this problem and it is very frustating to me since I do like zucchini, especially with tomatoes, onions and eggplant. I am not going to waste my time cooking this stuff. In the compost pile! Very frustrating. I have found that "grey zucchini" a lighter skinned variety found in some markets to be much more tender and never bitter.

It's interesting because I just got some more zucchini and decided to cook it longer - but the bitterness was still there! I sauteed it with garlic and tomatoes and cooked the hell out of it, but sure enough - still bitter. Oh well, maybe you are right.

This does stink because I love it, as well. Could it simply be WHERE the zucchini comes from this time of year? I don't remember any of the zucchini I've had in the summer tasting like this - the summer stuff also seems to be bigger. Hmmmm.

I swear I also get a hint of lavender with mine - but no one else seems to taste it.