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What's the white residue on red grapes?

elise h Dec 23, 2006 12:19 AM

I've noticed in the last year that red seedless grapes often have a white residue on them. I rinse the grapes and the residue appears to be gone. When the grapes are dry again, the residue appears. what is this? Hopefully, it's not pesticide.

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    MobyRichard RE: elise h Dec 23, 2006 12:24 AM

    Natural yeast. There have been recent posts about making sourdough starter with red flame grape yeast, if that's of interest to you.

    3 Replies
    1. re: MobyRichard
      blue room RE: MobyRichard Dec 23, 2006 12:29 AM

      Does this have anything to do with cream of tartar?
      I wonder why this yeast shows up on grapes (and plums?) but not on apples, tomatoes etc.

      1. re: blue room
        babette feasts RE: blue room Dec 23, 2006 12:34 AM

        tartaric acid forms in wine barrels

        1. re: blue room
          Eldon Kreider RE: blue room Dec 23, 2006 10:13 PM

          Apples naturally have yeast on their skins. This is why unpasteurized cider ferments so readily. However, supermarket apples have usually been washed and oiled or waxed to remove pesticides and to keep the apples from drying out.

      2. Melanie Wong RE: elise h Dec 23, 2006 10:18 PM

        No worries about pesticides, even grapes that haven't been sprayed should have a bloom on them. It's a natural waxy substance produced by the fruit to protect itself. Here's a cite from Welch's -

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