Ask Dr. Potato

Q: I’m making potato soup with Russet potatoes, barley, onions, and water. As the pot boils, purple foam is coming to the surface of the water. What causes this and is it safe to eat?

Q: How many pounds of potatoes would I need to serve scalloped potatoes to 100 people?

Q: We are planning to open a fries business but we want to use fresh potatoes, to reduce the work on site, we plan to deliver peeled potatoes to the stores. What is the best way to store peeled potatoes without them browning? Can I vacuum seal peeled potatoes? Is it required to cook potatoes first before vacuum sealing or just wash, peel then seal? Are vacuum sealed potatoes need to be refrigerated?

Q: I saw your post with someone asking what is the best method for keeping baked potatoes warm all day and you answered that a bread warming drawer would be best. What temperature should the drawer be at? Also, if I do not sell enough at the end of the day could I put them in the refrigerator and reuse the potatoes again the next day?

Q: My potato has large lumps in it and after baking and mashing it the lumps are not going away. What is this?

Q: I own two fast casual burger restaurants in middle Tennessee. We only serve Idaho grown potatoes. 50% of our orders are to go orders/take-out orders. While I understand that using styrofoam boxes is a huge no-no for bagging french fries, it is not clear what is recommended for proper bagging of hot french fries. I recognized that french fries need to be ventilated when bagged. What recommendations do you have for me for properly bagging french fries? What can you teach me when bagging french fries?

Q: Why do I need to use corn starch and vinegar while making restaurant potato fries?

Q: Is Black Dot Fungus on potatoes okay to eat once cooked?

Q: If I am cooking a potato in an electric roaster, after I was them should I still pierce them with a fork?

Q: Should I soak my red and yellow potatoes in water like I do for Russets?