0The New Complete Book of Food
Buying This Food
Look for: Bright red berries with fresh green caps. Pale berries are immature; berries with
dark, red wet spots are overmature; berries whose caps have browned are aging. Small ber-
ries are generally more flavorful than large ones.Storing This Food
Refrigerate strawberries with their caps on. When you remove the caps you tear cells in the
berries, activating ascorbic acid oxidase, an enzyme that destroys vitamin C. Keeping straw-
berries cool also helps keep them bright red; the anthocyanin pigments that make strawber-
ries red turn brown faster at high temperatures.Preparing This Food
When you are ready to use the berries, rinse them thoroughly under cool running water.
Then remove the caps. (If you hull the berries before you rinse them, water may run into the
berry and dilute the flavor.)
Don’t slice the berries until you are ready to use them. When you slice a strawberry,
you tear cell walls, releasing ascorbic acid oxidase, the enzyme that breaks down vitamin C.
This reduces the nutritional value of the strawberries. It may also be linked to the degrada-
tion of the pigments that make strawberries red. Acids retard the color loss; sprinkling the
sliced berries with lemon juice helps preserve color.
You can soften and sweeten strawberries by dusting them with sugar and letting them
sit for a while. The sugar dissolves in moisture on the surface of the berry, producing a solu-
tion that is more dense than the liquid inside the strawberry’s cells. Then the liquid inside
the cells will flow across the cell walls to the denser sugar-water solution (a phenomenon
known as osmosis); the cell walls that were held apart by the water will collapse inward and
the strawberry will be softer.What Happens When You Cook This Food
The red anthocyanin pigments in strawberries are heat-sensitive; they break apart and turn
brown when you heat them. Adding sugar speeds up the process even further because some
of the chemicals produced when sugars are heated also break down anthocyanins. That’s
why strawberries cooked in boiling, sugared water turn brown faster than strawberries
steamed quickly without sugar.
Red anthocyanins also change color in acids and bases (alkalis). They are bright red in
acids such as lemon juice and bluish or purple in bases such as baking soda. If you cook straw-
berries in an aluminum or iron pot, their acids will react with metal ions from the surface of
the pot to create dark brown compounds that darken either the pot or the fruit.
Strawberries also lose heat-sensitive vitamin C when you cook them.