avocado browning

I seem to recall hearing, some time ago on Dave Arnold's radio show, that one can keep an avocado from oxidizing by low temp cooking in a water bath. Anyone have any experience with this?

If so...time/temp? ...or maybe I am just making this up?

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Tim_Sutherland_52834

I too recall hearing or reading this somewhere, but I can't remember where. MC (both the book and website) discusses using water baths to slow oxidation but don't mention avocados.

Brendan_Lee_56950

He definitely talked about it. He said he hadn't tested it though.

I found this article dealing with PPO (polyphenoloxidase) in pineapples that suggests a residual activity of the enzyme of 1.5% or so after 5 minutes at 90C but what that will do to the texture of an avocado I'm not sure.

http://www.thaiscience.info/Article for ThaiScience/Article/1/Ts-1 thermal inactivation of polyphenoloxidase in pineapple puree.pdf

ipreferale

From my recollection, someone wrote in after, a chef I believe, and gave the temperature and time, but I cannot recall which episode it was.

Sumit__65166

in series 9 of good eats, alton brown suggests 40c for few hours.

http://youtu.be/W6u2igo0b3I?t=10m57s

them embedded video is not working for me. go to 10m57smark for more on this.

ipreferale

I have been unable to locate the Cooking Issues episode but I did find this on the Ideas In Food blog,

Bryce indicates that they cook them at 43 C for 1-6 hours. At 1 h they stay green for at least 24 h.

http://blog.ideasinfood.com/ideas_in_food/2008/06/avocado-tests.html

FrankM_3301

Excellent! Thanks. Should have thought to check their blog.

ipreferale

@Frank - You are welcome.. I just did one for an hour at 43 C, my plan is to cut it in half, vacuum one side and leave the other half in zip top bag and see what happens overnight. I hope it works...

Jack_Mayer_85396

@RED thanks for your experiments and your sharing here. As I frequently cook for myself, a technique for preventing/delaying oxidation with avocados would be most useful! Any of the real Pros have any thoughts ...

Kevin__55609

You'd be surprised how long it takes for avocados to brown just by simply putting in a container with an onion.

Jack_Mayer_85396

@Kevin, thanks I'll give that a try as well.

ipreferale

@Kevin - I'll have to give the onions a try. Here are the photos of the just sliced after coming out of the ice bath after 1 h @ 43 C, vacuum bagged, left out the pit so they would have the same surface area, and zip bag. I let them go for 4 days and as you can see there is minimal surface browning on the zip sample and no texture change. I did not take a photo of the vacuumed one as there was little to no change.

The one thing that I did notice is that the avocado appeared to be a little more firm after coming out of the bath after 1 h.

Tim_Sutherland_52834

I don't have pics, but I SV an avocado 43C for ~2hrs and left half, with pit, uncovered in the fridge for 3+ days. The top 5mm was all brown but everything under was fine both colour and texture. Out of the bath the avocado appeared to be firmer and larger. I will have the weigh it next time to see if it took water on.

FrankM_3301

@Red, what are the conditions for pic #3?

ipreferale

@Frank - Pic #3 is where I commented "there is minimal surface browning on the zip sample and no texture change." In other words as close to store bought ripe as I could want.

Kevin__55609

@Red - Thanks for sharing your findings. Really interesting.

Johan_Edstrom_5586

@RED, @Tim - Thanks a bunch!

vondes_593348

If you do not intend to use avocado at once, then wrap the fruit in a piece of paper and place it in the refrigerator, vegetable compartment. It can stay there for up to fourteen days. How to tell if an avocado is ripe? If the avocado is already sliced, it can only be stored for two to three days, before which it is necessary to pour lemon juice to avoid the darkening of the pulp and then wrap it in a food film.