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You've Been Asking - Potato Questions

  • What causes potatoes to turn green? The "greenish" colour is a natural but unwanted process that happens when potatoes are exposed to sunlight or artificial light. The brighter the colour, the more bitter the flavour will be in cooked potatoes. The colour change is actually chlorophyll developing in the skin along with increased levels of solanin. Solanin is a natural substance found just under the skin in all potatoes. It gives potatoes their flavour. There is little cause for concern about solanin being harmful. Research shows solanin is not stored in the body and is rapidly excreted. To prevent greening, store away from light. If it occurs, trim the green area away before cooking.
  • What causes potatoes to have brown centres or a hole inside?Why do potatoes darken when cooked? There are two possibilities. The darkening may be caused by a natural reaction with the iron in the potato. To prevent this, add a little lemon juice or vinegar to the cooking water. When potatoes are stored at refrigerator temperatures, the starch in them changes to sugar. When cooked, this sugar "carmelizes" or darkens. Store potatoes at cool, not cold temperatures.
  • What causes black spots in a potato? Black spots are usually bruises which are caused by rough handling. One type of bruising happens when the skin is broken. The potato forms a thicker layer of skin to protect and/or heal the wound. The second type of bruising shows up just under the skin or deeper inside the potato as a blackspot. This happens when potatoes are dropped more than six inches or something heavy is placed on top of them. Handle potatoes gently. Store in a cool, dark place. Remove any blackspots before cooking.
  • Why isn't the potato variety printed on the potato bag? There are no regulations requiring potato variety names to be placed on bags. However, the flesh colour and shape should be shown, i.e. Yellow Flesh Potatoes, Long Type. To help consumers make purchasing choices, many producers now label their bags by variety.
  • Why are potatoes sometimes thought to be high in calories or "fattening"? Some people think of potatoes as fattening and consider them taboo on a weight-reducing diet. Nothing could be further from the truth. One medium, baked potato only contains about 100 calories. Baked or boiled potatoes are already conveniently portioned, making it easy to control the calories. It is the extras, such as fat added during or after the preparation, that increase the number of calories. As a substitute for popular high-calorie potato toppings, consider these alternatives; yogurt with chives; whipped low-fat cottage cheese blended with lemon juice; grated parmesan cheese; calorie-reduced salad dressings; or a mixture of herbs.
  • Why do french fries sometimes go dark? If potatoes are stored at refrigerator temperatures part of the starch in the potato changes to sugar. The high temperature needed for deep fat frying causes the sugars on the surface of the fries to darken before completely cooking on the inside. Blanching potatoes in hot water (90 degrees Celcius) for several minutes removes most of the sugars and cleanses the surface of the fries to allow them to brown more evenly.
  • How can I make good mashed potatoes? Some varieties are better suited to boiling and mashing than others. For a fluffy mashed potato, choose a Russet variety because of its drier, fluffier texture. Soggy mashed potatoes could result from over-cooking, i.e. too rapid a boil or too long a cooking time. Sticky, gluey mashed potatoes could be caused by over-whipping. For perfect results choose a Russet variety of potato, add a small amount of water, cook on medium high just until fork tender and drain well and mash. If, despite your best efforts, your mashed potatoes are too wet, add some instant potato flakes and stir just until combined.

"Hollowheart" is a discoloured cavity in the centre of an otherwise healthy potato. It can be caused by rapid growth or possibly by sudden temperature changes early in the growing season. This condition doesn't affect taste or nutritional value of potatoes. These potatoes can be eaten but the hollow heart should be cut out. If you find a hollow centre in your baked potato, just remove the brown area before serving.