Dingy Guacamole Unavoidable As Time Passes

Jesse-
Is there a way to keep my gaucamole a bright green for more than an afternoon? Will citrus preserve its color?

Derek

Derek–

Unfortunately, avocado turns brown fairly quickly once it’s been mushed up for guacamole.  Citrus will delay the color change slightly (I use either lemon or lime juice in my guacamole, depending on what I’ve got on hand; sometimes I’ll also add a splash of tequila), as will putting the avocado pit in the bowl.  Short of commercial preservation and coloring techniques, nothing will keep your guacamole a vibrant green overnight.  It’s a dish meant to be consumed within a short time frame after making it.

13 Responses to “Dingy Guacamole Unavoidable As Time Passes”

  1. Dave Says:

    I always thought that oxygen was the main culprit. Usually the top layer browns first and the layer about one inch down stays green. So if you push the plastic wrap down to the surface of the dip, it should keep the top of it from turning. Just trying to think back to my restaurant days…

  2. Cortney Says:

    As I understand it, contact with metal speeds the oxidation process. Try cutting open your avocado with a plastic knife, and mashing them with a plastic fork in a non-metal bowl (I like ceramic). The lime juice goes a long way in slowing the oxidation process, too.

  3. Adam Fields Says:

    There’s an extensive experimentation section in Harold McGee’s The Curious Cook. He concluded that a) keeping the pit in doesn’t help, except where the pit covers it and prevents oxygen from reaching the surface and a lightbulb works just as well, b) added acidic ingredients help, but not a lot, c) oxygen is the main culprit, d) plastic wrap pressed into the surface helps a great deal, but only PVDC wrap (Saran Wrap) - other kinds of plastic wrap are too gas permeable to make any difference, and e) California avocados brown faster than Israeli ones.

  4. jwsharrard Says:

    I’ve never tried avoiding complete contact with metal—I’ve always used a metal knife and a metal fork or dough cutter to mash my avocado; but even storing it in a glass container with plastic wrap pushed down on top and a healthy dose of lime juice, it’s been my experience that leftover guac goes brown within several hours…. How long does your typically last with no metal contact?

  5. Troy Says:

    I think keeping the pit in the guac DOES stop it from turning color for a short period of time, but not overnight.

    By the way, one of my pet peeves is that people pronounce it GWAWKamole instead of the proper way, which is WOCKamole.

  6. Jim Says:

    WOCKamole

    Isn’t that a carnival game?

  7. Tommy Says:

    I’ve been told that adding a crushed up Vitamin C tablet will put the brakes on the oxidation process responsible for turning the avocado brown. Supposedly it also works for pesto. I would imagine this works on basically the same principal as squeezing some citrus over it, but I can’t offer a testimonial here as I’ve never tried it. My guacamole and pesto never last long enough for it to be an issue. Obviously you would want to use a small tablet, and only one, to avoid adding any noticeable bitterness. If you have access to a physics lab and can appropriate and/or concoct some sort of oxygen-free vacuum container in which to store the guac, that might be worth a try…

  8. Cortney Says:

    To be truthful, I/we usually eat freshly prepared guac within a few hours - the longer time resulting from guac being taken to a dinner party, and losing time in transit. However, I have had occasion to leave leftover guac in the fridge overnight and found the top 1/4 cm had turned brown. I just mixed it in and had pretty green guacamole. Personally, I will try and cover my guac with saran wrap next time if there’s any leftover.

    Once upon I owned a “lettuce knife” that I also used to cut open avocados, and hoped that the product information would plug its non-browning quality for avocados, too. The products I saw just mentioned that it doesn’t brown lettuce.
    http://www.crateandbarrel.com/family.aspx?c=746&f=23579

  9. derek Says:

    Thanks for all the advice. And admittedly, I was hoping for a magic answer. Being a selfish pig, I made guacamole from avocados smuggled into China from Hong Kong, and wanted to be the only foreigner to taste its mashed glory, but this meant I was going to have to refrigerate some. I tried the saran wrap (the cheap and probably micro-porous kind), and still got a nice brown top. I was hoping that the hard to find (at least where I live) citrus was the solution. And Jesse, you mentioned the commercial preservatives, which made me think about this one particular neighborhood grocer who sold guac in their deli case, and it was always green (which was weird because a) it didn’t seem to be a popular item, b) I can’t imagine them remaking it everyday, c) maybe they just stirred it in the morning (or all day and never giving it a chance)). And now when I come back to the States I have a question to ask them.

  10. Olive Says:

    I think that leaving the pit in thing is probably a tale- someone figured that it had to be either the pit or the skin that kept the avocado fresh, and for reasons that escape me, decided it wasn’t the skin.

    Commercial avocado dips and guacamole, even without preservatives, keep nicely (unopened) for days- you’ll notice that those are all in airtight containers, with the lid completely mashed into the avocado, so there’s no air pocket.

    I put some lemon juice on the exposed surface (not just mixed in) and mash it down with Saran wrap, and that’s worked fine for a day or two for me.

  11. June Says:

    Food Science 101: The browning is due to activity of polyphenol oxidase enzymes. (Same stuff that makes apples, bananas, etc go brown, different from the Maillard reaction, which is what makes toast and caramel brown.) Polyphenols are in the avocado, and oxygen is in the air. See here for more details:

    http://www.worthington-biochem.com/TY/default.html

    Polyphenol oxidase activity is inhibited at low pH - this is probably why lime juice and tomatoes are popular additions to guacamole. Salt may often muck with enzyme activity, too, but changing the pH and excluding oxygen are the best bets. Refrigeration will slow the reaction rate, but it will not stop the enzyme activity. If you’re storing it, pack it in small, airtight tubs full to the rim.

    The pit is an urban legend. Try a controlled experiment - that is, make a batch of guac, split to 2 containers, stick the pit in 1 of them (on the surface or buried). Any part in direct contact with the atmosphere will brown.

  12. June Says:

    Oh, and I forgot to add - chemically, sulfites are the most common additives used to inhibit polyphenol oxidase activity. It’s a common preservative for dried fruit - apples, pineapples, etc. - and wine. (People who get headaches after drinking wine often are allergic to sulfites.)

  13. ponysparkle Says:

    My 10 year old daughter is doing a science fair project on this. It all started when someone told me that the pit preserves the dip if you leave it in. Our experiment showed otherwise. Actually so far for at least the 1st hour using nothing at all kept it greenest but it all changed after the hour and the lemon juice prevailed. But with what we just learned from this site we might need to start over. darn it!

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