The Penn State researcher noted this action is not effective because the nutrient loss is irreversible. With such a high demand for fresh foods, many people do not give a second thought to alternatives, thinking that fresh food is always more beneficial than canned or frozen foods.
"There is also a fallacy that fresh spinach is always better than canned," said LaBorde.
This belief is not always true because, despite the damage done during the heating process for canned spinach, it may retain more of its nutrients than fresh spinach kept in the refrigerator for a few days. The same holds true for frozen spinach. Frozen spinach retains more of its nutrients for a longer time than fresh spinach because of the lower temperatures at which it is kept.
The researchers found that spinach stored in a refrigerator at 39 degrees retained more nutrients than spinach kept at warmer temperatures. While they found that substantial nutrient loss occurred at all storage temperatures, the cooler temperatures retained more nutrients for a longer period of time.
Keeping spinach in the refrigerator will slow down its nutrient loss. The spinach kept at 39 degrees retained only 53 percent of its folate after eight days. When it was kept at higher temperatures, the spinach lost its nutrients at an accelerated rate. At 50 degrees it took six days for the spinach to lose 47 percent of its folate and at 68 degrees it took four days. The same holds true for carotenoid loss. As temperatures were increased, the loss of nutrients also occurred at a faster rate.
Penn State's College of Agricultural Sciences and the Department of Food Science provided funding for this project.
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Contact: A'ndrea Elyse Messer
aem1@psu.edu
814-865-9481
Penn State
18-Mar-2005