strengthens the pectin with the aid of a natural enzyme called pectin methylesterase (PME) According to an article in the Journal of Agricultural and Food Chemistry, PME induces calcium and magnesium to act as a sort of buttress for the pectin They strengthen the pectin’s hold on the potato cell’s walls, which helps the potatoes stay firmer and more intact even as their starch granules swell and burst Like most enzymes, PME is only active within a certain temperature range, acting faster and faster as the temperature gets higher and higher until, like a switch, it shuts off completely once it reaches a certain level Think of PME as little factory workers hard at work building cars As their floor manager, if you apply a bit of pressure to them (in the form of heat), at first that will get them to work faster Cars will come off the production line at a faster clip But apply too much pressure (by overheating), and the little enzymes just won’t be able to take it any more, throwing down their tools and walking out Production slows to a halt For PME, that shut-off point is just slightly above 170°F Unfortunately, most home cooks don’t have an easy way to maintain a water bath at exactly 170°F for the requisite 15 minutes I needed to find an alternate way to maintain the pectin structure of the potato while still releasing the starch molecules, and it struck me: it’s as easy as apple pie What’s apple pie got to with French fries? Well, anyone who’s ever baked an apple pie knows that different apples cook differently Some retain their shape, others turn to mush The difference largely has to do with their acidity Thus, supertart apples like Granny Smith will stay fully intact, while sweeter apples like Macoun will almost completely dissolve Just like in a potato, apple cells are held together by pectin, and, as it turns out, acidic environments can reduce or even prevent the breakdown of pectin So what if rather than trying to fiddle with temperature, I relied on the use of acid to help the potatoes keep their structure? I brought two pots of cut potatoes to a boil side by side, the first in plain water and the second in water spiked with vinegar at a ratio of tablespoon per quart Here’s what I saw: ... held together by pectin, and, as it turns out, acidic environments can reduce or even prevent the breakdown of pectin So what if rather than trying to fiddle with temperature, I relied on the use... relied on the use of acid to help the potatoes keep their structure? I brought two pots of cut potatoes to a boil side by side, the first in plain water and the second in water spiked with vinegar