DEAR DR. BLONZ: Because they tend to be available year-round, carrots and broccoli are the staple vegetables in my diet. I select carrots with the tops attached to ensure reasonable freshness. My question is: How long can these two vegetables be kept in the refrigerator without losing a significant amount of their nutrients? -- D.D., Concord, California
DEAR D.D.: You have chosen a great pair of staples, ones that are available in most farmer's markets and food stores throughout the country. Depending on the way they are kept, you have a week or two with both.
Carrots can lose sweetness as they sit; purchasing carrots with greens intact provides a good indicator of just-picked freshness, as you say. Once purchased, though, you should remove the tops, as the greens tend to drain water and nutrients from the carrot. This makes perfect sense once you realize that the carrot is the root, i.e., the nutrient supplier, for the growing carrot plant.
Carrots store well in a refrigerator set no higher than 40 degrees F. They should be keep in a sealed plastic bag or container. They are at their nutrient and flavor peak for the first few days, and then begin to lose crispness and nutritional quality, slowly for the first couple of weeks, but then more quickly until they become limp.
Most of the carrots we get in the store are immature, having been picked that way to maximize tenderness and flavor. More mature carrots have a more "woody" texture and might not taste as sweet, but they can be kept for longer periods of time. In pre-refrigerator days, root crops such as carrots were kept in root cellars for up to six months. In those days, standalone taste was not as primary a consideration, as the vegetables were often used as ingredients in flavorful stews.
Broccoli, similar to carrots, keeps best at low temperatures (35 to 37 degrees F) in a high-humidity crisper drawer in the refrigerator. It can keep up to two weeks, and nutrient quality will slowly decrease during that time.
Temperature is the key. At temperatures just above freezing (32 degrees F), broccoli can be kept up to four weeks. This drops to two weeks if the temperature is 40 degrees F, and only five days if the temperature is 50 degrees F. Throughout all these storage periods, the nutrient content will slowly decrease. The University of Nebraska provides a good information page on the handling and storage of fruits and vegetables: tinyurl.com/mmgsvrw.
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