Everyone around here loves pesto. Much like the marinated peppers, pesto sauce has become a staple in our home. I make a batch every time my pots of basil are green and luxuriant again, and right now they’re growing wild. While I stick to my favourite pesto sauce recipe for it (from Ina Garten’s Barefoot Contessa Back to Basics), sometimes I wonder why my sauce is a tad bitter. I wonder if the nuts might have been bitter, and leave it at that without probing into the issue.
Just recently I discovered I was wrong about the poor nuts! The olive oil is the culprit here.
I stumbled upon the explanation for this on DelciciousDays.com, which in turn comes from Cook’s Illustrated:
“Extra-virgin olive oil contains bitter tasting polyphenols coated by fatty acids, which prevent them from dispersing. If the oil is emulsified in a food processor, these polyphenols get squeezed out and the liquid mix turns bitter.
The magazine further claims this is only a problem when mixing dressing or mayo, because in pesto the other ingredients as nuts and cheese are robust enough to cope with it. This is where I (Nicky) disagree; I rarely prepare pesto with extra-virgin olive oil in the food processor anymore – because of the indeed noticeable bitter outcome”
Who would have thought?
So anyway – now that we can’t put olive oil into the food processor, I added 1/4 cup water (just enough to keep it running) until it formed a thick paste. Once the paste was ready, I stirred in the olive oil and parmesan cheese. Voilà! No more bitter pesto!
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Since giving up the joys of oh so creamy but oh so bad for me alfredo sauce, I have become a huge fan of pesto. It’s just so good. At least at restaurants it is anyway. I’ve always been too chicken to try my own, but now that I know where to find a great recipe and have your sweetness hint, I’m ready to give it a go. So thanks!
hey … that is a good one. Thank you so much. I had pretty much stopped making pesto because of the bitterness here and there. Time to get some basil home again
CI is correct on the EVOO part – it can get bitter when subject to agitation in a food processor. Though it’s more time consuming, I find that if you use a mortar-&-pestle, there is less chance of that bitterness happening (and the pesto has more texture)
I also don’t like to use EVOO for pesto – just regular olive oil. Somehow I find that the stronger flavours of EVOO do not allow the garlic-herb flavours of the pesto to shine through.
Also sometimes the cheese can taste strange when pounded or agitated (depending on the quality of cheese, blending can separate out the fat), so I just mix it in in the end after all the pounding.
Totally agree with you about using the mortar and pestle. I did that when my food processor stopped working and the taste of the pesto was magnificent! I also like the idea of stirring in the cheese later. Full flavour guaranteed.
Hey, sorry to use a comment for troubleshooting, but I wrote a response to this pesto post a few days ago and, when I hit “Submit”, it claimed that it was a duplicate post. I didn’t see my original appear here, but I decided to wait and check again later since my computer may have been lagging or something of the sort.
Well, I just checked back and since it looks like my original comment didn’t go through after all, I just tried again to post – and again it said it was a duplicate comment!
any ideas? or maybe comments are closed for this post now? (I guess I’ll find out in a moment, haha)
*smacks forehead* ok, so that one worked. sorry to be experimenting with your comment space – feel free to delete these afterwords. I’m going to try to post what I originally wanted to say now…
“Aha! Maybe THAT’S why my pesto tasted so strange! I’ve frequently read that using a food processor to make pesto can leave the flavors lacking, but I didn’t know that about the olive oil. I’m sure there were several other things (mostly me being an airhead) that affected the taste of my first homemade batch, but now you’ve got me thinking about investing in a good-sized mortar and pestle. I have a mini one for seeds and small leaves, but I may have to ask for a large one for Christmas.
Thanks for sharing!”
.. and hey pesto, the problem is solved! Actually I encountered a similar problem awhile ago, when making mayonnaise – stupidly thinking using evoo would make my mayo taste better, when in fact, a more neutral flavoured oil was the way to go all along.
I’m thrilled to know this! I can’t wait to try another batch of pesto. I may have to mention this on my blog to, as I have an upcoming spinach pesto recipe!
I am going to have to try this. I’ve been wanting to make my own pesto for a while now.
Interesting….good to know!
~ingrid
I did experience that so I asked my italian boss what I was doing wrong and she said the same thing. Mix the pesto with a little bit of water then add the oil, or alternatively, mix it with only a little bit of olive oil. If you plan to freeze the pesto it is also better to add the oil when you plan to use the pesto, after thawing!
I recently made pesto using walnuts instead of pine nuts and it came out super nice!
I agree with the poster that commented on not using EVOO for pesto, as I too just use the regular olive oil. I have a friend that is Greek & she told me that EVOO is a nice grade olive oil to use, but it lacks in the essential antioxidants found in olive oil. Basically, EVOO or the really light stuff is supposed to be a finisher for dishes, rather than a starter. The darker green the olive oil is, the better it’s supposed to be for you. She should know her family in Greece has an olive farm. So, I only purchase the really dark green stuff. Saves on the wallet, EVOO is kinda pricey. OH! When I make my pesto, I use a food processor, no bitter agents in the end product. Just make certain that you are blanching the basil before blending, otherwise you’ll end up with a muddy brown mess that will taste like pesto, just won’t be the pretty green as pictured.
I had no idea about the OVOO making the pesto bitter but my italian friend swears by the pestle & mortar. Her grandmother insists upon using it and it comes out brilliant although it does takes much longer. Also make sure to add tons of parmesan and don’t forget the garlic! (I did once-disaster!) Oh and I don’t know if you did this but did you toast pine nuts and add it? And have you tried other nuts like walnuts?
PS: LOVE your blog! I’m most definitely giving you a call next time i’m in Bombay!
Thanks. I just goodled “Why is my pesto bitter?” and came up immediately with this! Thank goodness. And it actually make sense!!! I made a Caesar dressing the other day-using my good EVOO, and it was good in flavor, but alas, BITTER! And then the same thing again today with my homemade pesto. Make soooo much sense, especially seeing it happen twice in like 3 days. Thank you SOOOOO much for the help and I will try a different method next time
D Happy cooking!
The basil itself will turn bitter near the end of it’s life cycle. if your basil plant has begun to flower, try the leaves and make sure they aren’t bitter before waisting the other ingredients.
I have to agree with Rick. I harvested my 3 basil plants over the weekend, and made a big batch of pesto which turned out bitter, so I was looking for answers. Here and other places, I read the idea about evoo causing the bitterness, but that simply doesn’t ring true for me because I very often make dressings and pastes that are heavy in evoo, in the food processor, and I have never once before gotten any bitterness at all. I processed the heck out of last year’s pesto with evoo, and it wasn’t even slightly bitter, but I made that one in mid-summer instead of late summer. So, I tasted a leaf of what I used this time, to see if this late-summer basil was bitter, and it was! I have been using my basil almost daily in cooking, and hadn’t noticed the bitterness, but that’s because I was just using a tablespoon or two in a dish. Made into pesto, the basil flavor is really intense, and the bitterness was very noticable.
WOW, Mary. Thanks for sharing!
I’ve used all different kinds of olive oil, cheap, expensive, extra virgin, not extra virgin, and I’ve never noticed a huge difference. However, if I use basil from plants that have started to flower I most certainly notice a bitterness. I just learned about this flowers=bitter this summer, and I now know it’s something to really pay attention to!
Actually this is so true….till last year I used to buy basil when I needed it but this year I grew some and to be sure the leaves would taste more astringent when used from a flowering plant. Also the variety of basil seems to matter as some varieties such as opal basil are far more bitter than others.
But I also think the olive oil has to do with it – some EVOO’s are more peppery than others and when processed in a blender adds to the bitterness. I think the mortar and pestle is the way to go with pesto if you have the time.
Ultimately though, it’s the basil that’s more important. A friend’s Italian grandmom, who hailed from Pra in Italy and its from her that I learnt that the best basil to pluck from your plant is the smaller, more tender leaves that give a sweet flavour (which is the perfect 4th counterpoint to the punchy garlic, creamy olive oil and salty cheese).
Ok so this seems it is fundamental to any type of Pesto like preparation. My mom’s Gujarati Coriander Chutney is a similar preparation as Pesto. Except she has Cilantro instead of Basil and she adds hot peppers to it. She always adds vegetable oil (any Corn Oil or Sesame Oil preferred) after processing it in the food processor.
Ok so this seems it is fundamental to any type of Pesto like preparation. My mom’s Gujarati Coriander Chutney is a similar preparation as Pesto. Except she has Cilantro instead of Basil and she adds hot peppers to it. She always adds vegetable oil (any Corn Oil or Sesame Oil preferred) after processing it in the food processor.
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