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Machine Blades turning Olive Oil Bitter

Someone suggested that Machine Blades, presumably from a food processor or Liquidiser can turn Olive Oil Bitter. I do not know if this is true but if it is has anyone got an explanation for it. I am assuming also it is the blade movement that does this as all Olive oil here is stored in Stainless steel containers and it does not turn bitter just by being in contact with it. I am thinking of a situation where you are making mayonaise and Olive oil would be in a blender or food processor. ...Any ideas. Many thanks in advance

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  1. Olive oil itself can be bitter.

    If you want sweet, use butter.

    1 Reply
    1. re: DanaB

      DanaB, Thanks for the reply. I know Olive can be bitter. I have an Olive grove and Harvest the Oil. The reason it is bitter in this case is because the Olives have been left on the tree for longer to produce more oil but of lower quality. If you pick them early generally you will get a better product. I posted this because someone suggested that good oil can turn bitter when used in a machine and I am not sure this is true.

    2. Alton Brown in his Mayo show suggested that extra virgin couldn't handle the food processor

      "Now if you decide on using extra virgin olive oil, add it by hand only. It's got fruitier compounds that just can't take the slam dance of the processor. It will turn out bitter. Let's spin, shall we?"

      http://www.goodeatsfanpage.com/Season...

      Take Care

      - P.

      8 Replies
      1. re: Mattapoisett in LA

        Many thanks for this. I am English, living in Italy and I've no idea who this guy is. I'm still not sure of the science, what for instance is a " Fruitier Compound" but I will take this as anecdotal evidence. Another reply suggested heat caused by the blades. Thanks for taking the time

        1. re: sksiezak

          I may be wrong about this but when you have extra virgin or first press olive oil, look at it, its very dark with tiny bits of olive in it which give it an extrodinary good flavor. Those bits may burn and become bitter under heat or friction. When you use a lower quality olive oil it has less or none of those bits in it.

          As for Alton Brown he is a Host on the Food Network of his own show which uses Science to explain the process of cooking and he also is the commentator of Iron Chef America

          1. re: Mattapoisett in LA

            Shouldn't science be in quotes? hahaha ;-)

            1. re: Mattapoisett in LA

              I am in my second year of pressing my own Olives for Olive Oil. I would actually reject it if it had bits in it as would all the farmers round here. Also I think there are a lot of Myths surrounding Olive Oil. Thanks for the info on Alton Brown

              1. re: sksiezak

                If you don't mind my asking what makes the oil from first press a significanlty darker shade of green than regular olive oil? Some versions I've seen are almost opaque.

                1. re: Mattapoisett in LA

                  I am finding the term 1st pressing very deceptive. A lot of people think that this when the Olives are pressed and that the same olives are then pressed again to make oil. Hence a first and second pressing.There is a sort of truth in this but I'll come back to that. The first pressing refers to the first time you take the olives to the press. The press here in central Italy opens about the first week in October. We harvest the Olives and take them to the press. If you want good Olive oil you cannot leave the olives for more than 3-5 days depending on the condition. This means that with 2 people harvesting by hand you could take between 300-500Kg ( Sorry don't know llbs) to the press. When you take this first load to the press you get less oil but of better quality and indeed our Olive oil is extremly dark green at this point. It is then back to the fields for more harvesting and a week or so later you take the olives for the second pressing. Due to time constraints this year we did 4 pressings over a month. At first we got about 10 litres for every 100kg of Olives. My last pressing I got 24 litres for every 100kg of Olives. Actually the colour was more or less the same and the quality is still pretty good but the first pressing is definitely better. Now about the colour, this does lighten over time. The same Dark green Olive oil a year on is a lot lighter and yellower so it can indicate age. The Olive oil becomes more mellow. Some people like this. I myself prefer the Piquancy of the first pressing. The difference in colour can also come from the variety of Olives. I have heard that sicillian Olive oil is a lot lighter on the first pressing and they would definitely have a different type of tree. As for the term second pressing( Meaning the same Olives are pressed twice) there is a little truth in this. The rubbish that comes out of the Olives when they are pressed is a sort of brown Mud. This mud is carted off to industry for the last drop of oil to be extracted by a chemical process. I daresay it then finds its way into the food chain in such products such as Margerine with Olive oil. I would not call it food.So the answer to you question after all this rambling is either, different variety of tree ( and apparently there are about 300 different types of tree in Italy), Age of Oil or Olives picked late in the season or Olive oil that has been chemically extracted. I hope that helps. I'm off now to try and prune some of these trees, an art and a skill all of its own that I have yet to learn properly

                2. re: sksiezak

                  My ND (Doctor of Naturopathy) tells me that the fresh olive oil with particulate in it is the best kind for health.

              2. re: sksiezak

                This is an old thread, but dude, if you have internet access look up Alton Brown. He is a fantastic ressource.

            2. Heat.
              The friction from the blade produces enough heat to break down very delicate oils and cause them to get bitter.
              Sometimes you can get away with short bursts of the FP, but it's better to do some things by hand.

              2 Replies
              1. re: MakingSense

                Dear Making Sense. Many thanks for this but it still is a bit Vague. How can Olive Oil have delicate Oils within in it. Its just Oil from the Olive. It maybe that something within this compound turns bitter but think of this, that means that everytime you cook with Olive oil you would have a bitter taste when you heated the oil which I am sure is not the case. I will take your suggestion though and do it by hand. I'll let you know the result of the experiment

                1. re: sksiezak

                  Different oils begin to break down at different temperatures. When you heat them, they have different "smoke points," for instance, and some will burn and turn bitter at much lower temperatures than others.
                  Olive oil breaks down at a lower temperature than peanut oil so you wouldn't use it to deep fry ordinarily but it works fine for sauteeing. Use different oils for different jobs...

                  I have not personally had a problem with olive oil getting bitter when I have used a food processor to make pesto, mayonnaise or other sauces. I don't use it for very high heat cooking.

              2. i'm sorry, but i'm seriously dubious about this. how long must the oil be whirring around in the processor before it becomes "hot" enough to degrade? this sounds like nonsense.

                further, it's being combined with other ingredients, which even if this was remotely true, would mitigate the heat.

                i've never watched this anton guy, but did attend culinary school, and worked in professional kitchens and i've NEVER heard of this. nor has it ever been a problem for me at home. poor quality oil will be bitter.

                1. The OP's question was theoretical as was the answer.
                  While it's not likely that someone would wizz oil alone long enough to generate that much heat, it is possible. I'm sure in your professional career, you have seen lots of "nonsense" that you never dreamed someone would do.
                  Food processors have a breaker switch that cuts them off when they get too hot. Mine has been activated several times over the years even though I don't abuse my equipment.

                  Poor quality oil might or might not be bitter - some just have little or no flavor. Bitter oil might or might not be of poor quality - it could be very fresh or simply a regional variation as some Tuscan first pressings are.

                  2 Replies
                  1. re: MakingSense

                    a breaker switch is responding to the temperature of the motor, not the contents of the mixing bowl.

                    olive oil does eventually go rancid, which makes for a bitter taste as well.

                    1. re: hotoynoodle

                      I think this claim is doubtful. Ive never had a problem using high quality olive oils in the food processor. Unless you are using warm ingredients, the contents should never more than slightly warm in normal operation - Id be afraid the unit was going to burn out if it did get hot. And simply the use of the steel blades? again, very doubtful.