Fresh Produce.

24 06 2009

Vegetables, especially leafy vegetables, deteriorate much like radioactive material; they have a sort of half-life. The mineral content is stable, but in respect to the vitamins and enzymes and other complex organic components, each time period or “half life” results in the loss of half the nutrition. Suppose a lettuce has a half life of 48 hours, two days after harvest only 50 percent of the original nutrition remains. After two more days, half the remaining half is gone and only 25 percent is left. After two more days half of that 25 percent is lost. Thus six days after harvest and a lettuce contains only bout 12 percent of its original nutrition. A two day half-life is only hypothetical. Those types of produce I classify as very perishable probably do have a half-life of from 36 to 48 hours. Moderately perishable produce has a half life of about 72 hours; durable types of produce have half lives of 96 hours or longer.

Vegetable Storage Potential
Very Perishable Moderately Perishable Durable
lettuce zucchini apple
spinach eggplant squash
Chinese cabbage sweet peppers oranges
kale broccoli cabbage
endive cauliflower carrot
peaches apricots lemons
parsley beets

The half life of produce can be lengthened by lowering its temperature. For that reason, sophisticated produce growers usually use hydrocooling. This process dumps a just-cut vegetable into icy water within minutes of being harvested, lowering core temperature to a few degrees above freezing almost immediately. When cut vegetables are crated up at field temperatures, and stacks of those crates are put in a cooler, it can take the inside of the stack 24 hours, or longer, to become chilled. Home gardeners should also practice hydrocooling. Fill your sink with cold water and wash/soak your harvest until it is thoroughly chilled before draining and refrigerating it. Or, harvest your garden early in the morning when temperatures are lowest.

Still, when you buy produce in the store it may have been sitting at room temperature for hours or possibly days.

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