20 Responses to “A shocking (and hot!) tip for preserving produce”

  1. Jenn M says:

    Interesting. However, how does this process affect the taste and texture of fruits and vegetables. I’m particularly curious about lettuce for texture and oranges for flavour.

  2. Dave says:

    I got this about a week ago via an email from the Washington Post & immediately tried it on some grapes with fantastic results. Is there an associated , by-item listing of the expected increased storage time?

  3. Rickard says:

    I have to toss out a lot of leafy greens like spinach and ruccola. Can they be made to last longer using this method?

    What is the best way to store leafy greens? I’ve been taught to use a non-airtight container with a dry paper towel in it to soak up moisture.

    Thanks for an informative article.

  4. Scott says:

    Are there any forms of produce that should not be heat treated?

  5. Bill says:

    Strawberries are mentioned in the article, but there is no time/temperature guide. They are a fruit that does not keep well, and I would love to try this technique. Any guidance on time/temp? Thanks

    • Judy says:

      Hi Bill,

      We recommend 60 C / 140 F for 15 seconds for strawberries. You can find more guidelines on page 3·359 of Modernist Cuisine.

  6. Wayt says:

    Re: Scott’s question: Heat-shocking works best on minimally processed produce–fruits and veggies straight from the orchard, garden, or farm. Supermarket produce that originated thousands of miles away or is packaged for long shelf life (e.g., bagged or boxed greens) most likely already received either a heat treatment or a chemical wash of some kind. Heat-shocking such items at home will probably do little to further extend their longevity.

  7. Martin says:

    How does this treatment compare to cold shocking vegetables? I’ve watched Heston Blumenthal in one of his shows revive iceberg lettuce by putting it in ice water for 15 minutes.

    • Wayt Gibbs says:

      That can work for certain green leafy vegetables. Heat-shocking delays wilting; it won’t rescue already wilted leaves. Heat-shocking only works if used in advance of spoilage, but it works on a wider range of produce.

  8. curtdbz says:

    Thanks a lot for this tip! Two questions:

    1) Does this leach any nutrients out of the vegetables the way that boiling them would?
    2) Please tell me this works for bags of milk. I dread the days that come close to the expiration date. (but seriously, do you know of any tricks to extend milk’s shelf life?)

    Thanks as always.

    • Wayt Gibbs says:

      Some nutrients (e.g., certain vitamins) are water-soluble, so any water treatment (even washing) diminishes them by a bit. But heat-shocking at the temperatures recommended in the column won’t have nearly the nutrient-altering effects that blanching or boiling does.

      As for milk, long heat treatments should effectively deepen the degree of pasteurization and thus extend the safe shelf-life. If you search in Google Scholar for ultrapasteurization protocols, you will find an extensive literature on this subject. I don’t know for certain whether this treatment, in the absence of vacuum sealing, will prevent the formation of off-flavors, however. In many cases, the bacteria that create off-flavors are different from those that cause foodborne illness. Chemical effects, such as the oxidation of milkfat leading to rancidity, can also produce off-flavors independent of biological activity.

  9. Jonathan Kaplan says:

    Thoughts on cucumbers? Will it help? Time / temperature recommendation?

  10. Peter MacKichan says:

    Can you heat shock herbs?

    • Judy says:

      Hi Peter,

      As Wayt noted above, it will depend on whether or not they were treated before hand. Try it on herbs fresh from your garden or farmers’ market, but bagged or otherwise packaged herbs from the grocery store may have already been treated for longevity.

  11. fg says:

    I asume these times and temps are ideal. How much can they be fudged and still be beneficial?

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