DEAR DR. BLONZ: How long can vegetables such as carrots or broccoli be kept in the refrigerator without losing a significant amount of their nutrients? These are the vegetables we tend to buy regularly, always having them available for a meal. -- E.P., Oakland, California
DEAR E.P.: You have chosen a great pair of staples: ones that are available in most farmer's markets and grocery stores throughout the year, in most parts of the country. Depending on the way they are stored, you should have a week or two for the broccoli and about a month for the carrots, after which points both will have begun to experience decreases in their nutrients and flavors.
Carrots can lose sweetness as they sit, so purchasing carrots with fresh-looking greens intact can provide a good indicator of just-picked freshness. Once purchased, though, you should remove the tops, as the greens drain water and nutrients from the carrot. This makes perfect sense, given the fact that the portion of the carrot we consume is the root, which is the nutrient supplier for the above-ground greens.
Carrots store well in a refrigerator set no higher than 40 degrees F. They should be kept in a sealed plastic bag or container to prevent loss of moisture. They are at their nutrient and flavor peak in those first few days, and then begin to lose crispness and nutritional quality -- slowly for the first couple of weeks, but then quickly downhill until they become limp. If it gets to the point where the carrots become spotted or discolored, or get slimy, they are only fit for the compost bin.
Most of the carrots we get in the store are immature, being picked that way to maximize tenderness and flavor. More mature carrots often have a more "woody" texture, and while they might not have the same sweetness, 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. Sustenance was the primary consideration in those times, and stored vegetables could always be incorporated into slow-cooked, flavorful stews.
Broccoli, similar to carrots, keeps best at low temps (35 to 37 degrees F), preferably in a high-humidity crisper drawer in the refrigerator. A perforated plastic bag is recommended to prevent wilting. Give your fresh broccoli a sniff and use that scent as a mental benchmark for later.
Count on broccoli keeping for up to a week or so, and possibly longer. 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 41 degrees F, and only five days if the temperature is 50 degrees F.
Nutrient losses will be insignificant at first. Signs that things have begun to turn are new odors, signs of discoloration (yellowing), and a loss of the rigid texture that characterizes this vegetable. At that point, this broccoli should share the same fate as over-the-hill carrots.
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