Psst... We're working on the next generation of Chowhound! View >
HOME > Chowhound > General Topics >
Jun 9, 2002 10:40 PM

Why did our Pesto turn out funky?

  • c

Why did our fresh (bought yesterday) basil pesto turn darkish color and taste bitter after it went on the pasta? The basil was fresh, the olive oil top quality, and it was a bright color when we blended it up. Wasn't very good at all.

  1. Click to Upload a photo (10 MB limit)
  1. Could it be that you used *too much* basil? I know this is heresy, but more basil isn't always better; it actually is a bitter flavor...Try adding more olive oil, cheese and pine-nuts, and see what you think.

    1. First off, always blanche and shock the basil(that elimates the dark color), next too much oil is not a good thing, add the cheese, pine nuts optional. DONE

      2 Replies
      1. re: russkar

        Yes, the shocking of the basil is an important step to keeping that beautiful green color. Try putting a piece of Saran wrap directly on the surface of the finished pesto to prevent oxidation (browning). Along the lines of not adding too much oil while blending - try substituting some water for oil - without enough liquid you won't be able to blend the ingredients - easy to get an overly greasy/oily pesto if you add to much olive oil to make it blend easily.

        1. re: gordon wing

          Good point, I do the Plastic Wrap thing already with pesto and Guacamole or any other oxidizing surface.

      2. *Cutting* basil will cause it to blacken, especially when the basil is then exposed to air; if you made the pesto in a blender or food processor, that might be the reason for discoloration. Maybe you over-processed it? Or let it sit uncovered too much. As for bitterness, that could come from the oil; some olive oils normally tend to be bitter.

        1. Blanch and shock the basil...add a bit of lemon juice to the pesto...when placed in the jar, pour olive oil on top to block the oxidation. No matter what you do, some of the pesto will blacken ,but it shouldn't affect the flavor. I make a point of making pesto with little oil, then the oil I use for cover is mixed in, pesto used, and more oil added.

          1 Reply
          1. re: Jim H.

            I never blanch the basil and it never darkens or tastes bitter. I put olive oil, pine nuts, and garlic into the blender, then add basil leaves and some reggiano. Before serving I dilute the mixture with some water that the pasta cooked in and it stays a gorgeous emerald color and tastes delicious.

          2. While it is difficult to tell why your pesto turned bitter as there are many possible reasons I'd be willing to bet that the culprit was the basil itself. The quality of the basil found in this country is so variable and to a large extent because a lot of the basil grown is not of the Genovese variety that should be used for pesto. Unfortunately, it is not simply enough to look at it as there are some other varieties and look similar but taste vastly inferior (for pesto); after some bad experiences I will not buy basil without first testing it. Rub a leaf and then smell the basil oil left on your fingers. The Genovese basil has a wonderful complex bouquet, while other varieties are more pungent with a unidimensional fragrance that will often produce bitter pesto.

            The second most likely source is improper storage, which other messages have addressed already.

            Finally, to my taste, pesto loses enough of its flavor after half an hour that I make a point of making only enough to eat at a sitting. Sure, I am often happy if I relax this rule, but that does not mean that there is no significant loss in taste: the fresh bloom is off. If I do not use the basil right away I buy plants with the roots on. If you keep the roots in water the basil will still give you a "fresh bouquet" 2-3 days later, a richness of taste that is usually lost in storage. Without roots on, I detect a loss of taste after about half a day after it is picked and then it gets progressively worse and it will become a tad bitter after a while.

            It is the quality and freshness of the basil that counts most.

            I hope this helps.

            2 Replies
            1. re: Octavian

              I thought this post pointed up a useful fact - that sometimes the bitterness is in the basil. Often in NY the basil comes to market when it is blooming. My heart always sinks when I see the big bunches at the farmers market, becasue the growers waited too long to pick; at this stage the leaves will be bitter. You should always look for the soft young leaves, not the old thick ones, especially if they are getting smaller toward the top of the plant and use the leaves only, not the flowers or stems. Also, the Genovese basil is better, but you have to look out for it or grow it yourself.

              I usually make bulk pesto according to Ed Giobbi's old recipe - 6 packed cups of basil leaves, blanched leaves (just dip them in the boiling water) ground with a a few garlic cloves (put these in first and chop em up before puttingin the basil) and a cup more or less of parsley, some pine nuts (1/2 cup maybe) and olive oil (enough that it moves in the processor or blender, no more), blend until creamy pack immediately into freezer containers and cover with a layer of olive oil. When it freezes, add some more oil, and make sure the entire surface is well covered and stays that way, To use, thaw rapidly and add salt and cheese (parm and romano, 1 or both)to taste.and a pad of butter or a bit of cream if wanted.

              This pesto keeps very well in the freezer for up to a year as long as you keep the paste covered with oil - in my more ambitious days, I made several pints at a time to get us through. Usually made a batch without pine nuts to use with minestrone, etc Now that my needs are diminished, I have experimented with single meal versions, and find that the fullest flavored tasting pesto of all is made with the mortar and pestle but the blender version is perfectly adequate.

              1. re: jen kalb

                p.s. dont blame Mr. Giobbi for this recipe - I am recalling it from memory having made it many times,and my proportions may be a bit off those he recommended esp for olive oil. Maybe I should mention that it is a temptation to put in damaged leaves given the cost of basil, but dont do it!
                Blackened, bruised or browned leaves can definitely have a bad effect on the flavor of your pesto.
                A final thought - dont scrimp on the oil - that is what is preserving your basil from oxidation (exposure to the air) and going off in flavor - it should be a smooth creamy emulsion of oil, basil nuts, garlic and cheese.