Help with agar filtration

[KennethT]

So, yesterday, I tried to make a clear mint liquid using agar filtration. The resulting 'consomme' which came from the dripping agar puck was "clear" but it was also brown!!! It has an intense mint smell...

I think one problem started when I was pureeing the mint in the blender - I think the speed of the blender actually cooked the mint a bit - because when I went to strain the liquid it was quite warm... but the mint puree was a dark green color...

To mix with the agar, I heated the agar with a small quantity of boiling water, then, when dissolved, I mixed this hot water/agar mix into my strained warm mint liquid. Then put into a plastic bag and froze.... After frozen, I put the pieces into a strainer lined with cheesecloth and waited - about an hour later, I checked it, and what was dripping out was a clear brown liquid... by now, all dripping has stopped and I'm left with a dark green sludge in the strainer, and clear brown mint liquid...

I guess the mint liquid oxidized... should I have added some VitC powder or something to my puree to keep it from oxidizing? What else could I have done to prevent this??

I'm still figuring out how to post the pics here - but there's a folder in the ImageGullet with them...

[johnder]

You should check out Dave Arnold and Nils Noren's Cooking Issues blog over at the FCI. He talks a lot about agar clarification.

One of the posts are here.

[KennethT]

John, thanks for the link... I had actually read those articles in the past, which sparked my idea for the clear mint liquid... I think my biggest problem is that the mint cooked in the blender and oxidized - the resulting brown liquid, while being minty, did have an oxidized note - you don't have that problem with OJ because there's already so many anti-oxidants in it... but thinking about it - if you cut up a bunch of mint and leave it out, what happens? It turns brown at the edges... like an apple...

[Tri2Cook]

A quick blanch and shock helps as does a bit of ascorbic acid. Personally, if I was going to do a clarified mint water, I would probably cold infuse very lightly crushed mint into the water and use gelatin filtration so that it never had to be heated. If you're using the freeze/thaw method with the agar, the gelatin won't take all that much longer unless you're doing a very large amount.

[KennethT]

success!!!! I tried again using Dave's quick agar method (no freezing - just set in ice bath until set, then break up the curds and press through cheesecloth).. it worked great - I now have a pale greenish clear mint water that has a great mint aroma... A few things that I think helped: Vit C powder when pureeing the mint... plus I used a food processor rather than the blender - no, it didn't puree the mint as thoroughly, but the food processor didn't cook my mint while doing it...

Tri - I think your idea of using gelatin is a great one - but one person who will be (hopefully) enjoying the mint water is vegetarian and while there technically wouldn't be any gelatin in the water, I don't know how much of a sticking point it would be if she knew that gelatin was used in the process...

Thanks for the help!

Ken

Edited to correct my crappy grammar

Edited August 23, 2009 by KennethT (log)

[Tri2Cook]

Yeah, ascorbic acid usually does the trick. The method you used is my first choice for clarifications now so if it did what you wanted that's great. I was excited when Alex introduced it on Ideas in Food and then the Cooking Issues guys made it even easier the very next day. The internet is a really cool thing sometimes.

[thampik]

Sorry if this is not the best place to post this request for help..I am trying to get some beef stock clarified using Agar Agar and having a mare.

I am using a Clearspring Agar Agar product that specifies using a tablespoon per cup of liquid (Clearspring). I brought the beef stock to the boil and dissolved 6 tablespoons in it, froze it overnight and left to defrost at room temperature.

I ended up with about 50ml of crystal clear consomme and the rest remained stubbornly gelled.

Surely this cannot be the correct yield?

[Tri2Cook]

Way too much agar. The recommended amount of agar on the package is too much for what you're wanting to do. The package is assuming you want a nice, strong result typical of agar gels, you don't. You want a very light, easily damaged gel structure. Go with .2% agar by weight to the total amount of liquid, 1 gram agar to every 500 grams liquid. You should be much happier with your results. Also, check out the post on Cooking Issues regarding agar clarification... it eliminates the freeze thaw cycle completely.

[thampik]

Thanks, I had a feeling that too much Agra could have been the culprit..I'll give this another try and report back

[thampik]

OK, so the second time with the 2g of agar worked much better.

I started out with approx 900 ml of stock and I have now about 400 ml of crystal clear consomme.

I still have what seems a lot of the agar "curds" left over.

Would re-freezing this and leaving to defrost once again work?

[thampik]

FWIW re-freezing and defrosting again works - some more consomme has been extracted.