As a potato expert can you advise me on a situation that has developed at our restaurant? 

We serve fresh cut Idaho® Russet Potatoes, we have been doing this for 4 years. Potato quality was consistent over the period. Recently, the over the last month all of the potatoes turn dark in the fryers before they are done. Finished product is very dark and not crispy. We are using the same vegetable fry oil we have always used and change it every 3 days.

We 1st cut the potato and then let them sit in 5 gallon buckets of fresh water, until we immerse them in the oil based on orders to the kitchen. Our customers have noticed the change and our quality has suffered.

Changing suppliers did not help. I assume there may be a difference in this falls crop? Will the amount of starch or sugars in the potato have something to do with it?

Two things are happening; a transition from old crop to new means that the old crop usually has lost some of its water moisture and fries up quickly. The new crop still has to mature, has excess starch and sugar and won’t perform the same as old crop. Try blanching about 10 degrees less for a longer period. Once the potatoes mature it should come back to normal, about thirty days.

The other thing to check is the variety; you will have better luck with the Idaho® Russet Burbank variety.