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15 Quick tips on Vegetable Purchase and Cooking

1. What is the maximum boiling time to use for green vegetables? Why?

  • 7 minutes, to preserve color and nutritional value (i.e. lessen loss of water-soluble vitamins)

2. What is the primary pigment in green vegetables?

  • Chlorophyll

3. Name two things that will turn green vegetables off color.

  • Long cooking time, reactions with other ions/metals such as iron, contact with acids (e.g. lemon juice)

4. When used in stir frying, vegetables should be cut fairly small and on a slant. When prepared by steaming, most vegetables should have a slit put in the stem. The reasoning behind both practices is the same. Why should the vegetables be prepared in such a way?

  • To increase the surface area in order to reduce the cooking time needed

5. White vegetables such as onions and cauliflower will turn yellow under alkaline conditions. How can you preserve the natural white color?

  • Add an acid such as lemon juice to neutralize the alkaline conditions. Heating and adding sugar can help, too, because they denature enzymes that produce color changes.

6. What is the major pigment in carrots?

  • Carotene

7. What is the major pigment in red cabbage?

  • Anthocyanin

8. What will adding an acid such as vinegar (acetic acid) do to the color of red cabbage?

  • Preserve the red color

9. What will adding an alkaline substance such as baking soda (sodium bicarbonate) do to the color of red cabbage?

  • It will turn the cabbage blue because the acids are neutralized by the alkaline base

10. Which of the above pigments is the most color stable? Why? Carotenes are the most stable because they are fat soluble.

11. What effect does baking soda have on the texture of most vegetables? Why?

  • Baking soda turns most vegetables mushy because it breaks down the fibrous pectin in the cell walls. Baking soda also decreases the vitamin content, which is why it is not recommended.

12. Tomatoes and potatoes should be stored at room temperature. Why?

  • To preserve flavor; potatoes turn mealy at low temperatures because the starches are converted to sugar

13. In general, is moisture good for vegetable storage? Why or why not?

  • No, because moisture
1) leaches out water soluble vitamins,
2) encourages rot and mold growth, and
3) encourages bacterial growth.

14. Why do so many grocery stores mist the greens in the produce department? Is that a good idea from a nutrition standpoint?

  • Grocery stores mist the greens because it makes the produce look better and fresh — not wilted. However, it is not a good idea from a nutritional standpoint.

15. Name three cooking methods that best preserve color, texture, and nutrient content of vegetables. Why do these methods work so well?

  • Steaming, stir-frying, and microwaving allow for quick cooking with low exposure to water.

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