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Can cornstarch get too old?

ElizabethS Aug 20, 2013 03:12 PM

Thickening with cornstarch has always been hit or miss for me - today I thickened some fabulous (IMHO) lamb jus (about 1.25 cups) with the properly done slurry of cornstarch (1 tbsp CS/1 tbsp cold water) ...... and nothing material happened.

I served it anyway - it was delicious but I would have liked it to be thicker. Reducing it further wasn't an option because the flavour was perfect.....reducing it would have made it too salty/too acidic.

I make a great roux for gravy but didn't want that effect for the lamb jus.....maybe try arrowroot?

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  1. chefj RE: ElizabethS Aug 20, 2013 05:47 PM

    I have never had cornstarch lose it's thickening properties from age.
    Did come back to a Boil?
    Acids can reduce corn starches ability to thicken.
    Whisking to vigorously can make it not work, but it usually thickens first and then thins out.

    2 Replies
    1. re: chefj
      ElizabethS RE: chefj Aug 20, 2013 07:52 PM

      Not a hard boil.....I thought that thinned it out again?

      Maybe it's the acid.....there was a fair bit of red wine in the jus

      I didn't whisk hard - but it didn't thicken off the top at all.

      Maybe cornstarch is just my nemesis! Thanks for the thoughts.

      1. re: ElizabethS
        firecooked RE: ElizabethS Aug 20, 2013 09:27 PM

        You need to be at a full boil for a minute or so for it to properly thicken. The recommended ratio is 1 TB to 1 cup, so you may have just needed more cornstarch.

    2. firecooked RE: ElizabethS Aug 20, 2013 09:32 PM

      My favorite for thickening is a buerre manie.. A mixture of flour and softened butter. You just keep adding at the end until you have the desired consistency. You do get a nice butter flavor.... Not sure if that's what you want.

      1. iL Divo RE: ElizabethS Aug 20, 2013 09:40 PM

        MIL used arrowroot never corn starch. I've never used arrowroot rely on corn starch.
        can it lose its' umph, prob. it's only about a buck-I'd toss yours & get a new Argo.

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