Potatoes contain the enzyme pectin-methyl esterase (PME). Par-boiling potatoes at a temperature range between 130F to 140F, activates this enzyme, gelatinising the starch cells in the potato.

According to Dave Arnold's experiments on Cooking Issues, this results in french fries that stay stiffer after frying. In my own testings, I have found that par-boiling potatoes at 140F before cooking them creates fluffier mashed potatoes as well.

Experiments on this enzyme that I have found online seem to test them on french fries, but they don't mention what variety of potatoes they use; high starch, waxy, low-moisture, high-moisture.

  • High-starch, and low-moisture: Russets, Idahos, Yukon Golds

  • Waxy and high-moisture: Granolas, Fingerlings, Desirees

My question is, does the temperature range and effects of PME activation differ between varieties of potatoes?

  • "Boiling" would be an inaccurate term for cooking in 130-140°F water, unless its being done at 35-39,000 feet above sea level, or in a partial vacuum. – Ecnerwal Oct 25 '17 at 18:10
  • @Ecnerwal Yep, I have edited the description. – user60513 Oct 27 '17 at 9:50

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