Is ice water more effective than room temperature water for leaching out starch for making fries? Also, do you know what method creates a light and crispy exterior verses one which is hard and leathery? Is it the potato or the process?
Chilling the water or adding ice is a method that helps the cells seal up and makes for a crisper fry when blanched. Warm or room temp water is better for leaching the starches, some operators or manufacturers actually blanch (or boil) the potatoes in water to remove excess starches. Many making fresh cut fries, first cut the potatoes, rinse in water till the water is clear, then transfer to plastic buckets with water, place in the walk in and come back in a few hours. Typically the excess surface starch will drop to the bottom of the bucket. By the way, this excess starch, when captured, makes an excellent thickener for soups and is gluten free too!
Light and crispy defines the results you get from using a high solid, low moisture potato. Typically, the Russet Burbank variety from Idaho works very well for this. Medium to medium high solids, such as the Yukon Gold or Russet Norkotah can work, but I have found that you need to blanch them at a lower temperature for longer. Search “high solids” and “fresh fries” on the Dr. Potato web site, top right corner. You can also scroll down to the cloud words (most often mentioned) and click on solids or fries or starch there. It could also be the oil type or oil temperature, when a lot of potatoes are added at once it drives down the temperature.