Keeping the Harvest Freshcomments (2) July 7th, 2009
It was my first garden. All season I worked and worried that just as the familiar pot wouldn't boil, my garden wouldn't produce. But there they were, my first ripe tomatoes. They were smooth and firm, fitting perfectly in my soil-roughened hands. Cradling them affectionately, I whisked them to the kitchen and placed them-well, all but one-gently into the back of the refrigerator. I thought they would be safe there until the weekend when I could share them at a family gathering. But at the picnic when I proudly carved the soft, drippy spheres into small pieces and passed them around, no one was impressed. Baffled, I took a bite myself-they were mealy! What had I done?
Years later, I can laugh at the injury I caused my precious tomatoes during that first season. Post-harvest damage accounts for up to 50% of vegetable losses worldwide, and I suspect this figure isn't much different in most homes. But damage to fresh-picked produce is easy to avoid. Understanding the ins and outs of caring for vegetables once they leave the garden can spare you much heartache and even keep a bit of your garden alive well into the dark winter months.
Vegetables in the kitchen are as alive as they were in the garden, but they need a different kind of care. The hot sun and a good soaking with the hose no longer have any appeal, but the basics still apply-the temperature, water, and air around them affect their appearance and health.
To chill or not to chill
To live, vegetables must make energy, even after they have been harvested. They constantly break down the carbohydrates, proteins, and fats they created with the help of the sun into simpler materials. Without roots, leaves, and soil, vegetables can't replenish these substances as they could in the garden. Through a process called respiration, these materials break down faster and faster as air temperature rises. Once the carbohydrates, proteins, and fats are gone, vegetables die. So, the lower the temperature, the longer vegetables' food reserves last, and the longer they stay in good shape.
As a basic rule, cool your vegetables down as low as you can without injuring them. Under this rule, vegetables fall into two temperature categories: those you should store at temperatures just above freezing, as in a refrigerator, and those you should store at temperatures a bit higher. The chart How Long Will Your Vegetables Last? lists storage requirements for different vegetables. While kale, carrots, and beets like the cold, refrigerators can be terrifyingly frigid places to other vegetables. Full of chilly metal bars, these holding cells are debilitating prisons to beans and winter squash, and particularly to vegetables from tropical and subtropical areas of the world, like tomatoes, eggplants, and sweet potatoes. While freezing temperatures will certainly sabotage most crops, these vegetables feel chilling damage at temperatures well above freezing.
Chilling injury is a complex syndrome. The vegetable variety, length of exposure to chilling temperatures, length of exposure to warm temperatures after the chilling ones, and the growing conditions experienced in the garden all affect the extent of chilling injury. For example, some okra may be delicious coming from the fridge after two days, but by the end of the week will develop disgusting, wet sores. A pepper may shine straight from the fridge after two weeks, but leave it out on the counter for a few days and it will look like it's been pelted with miniature rot-causing meteors. Or a pepper left in the refrigerator for four weeks may pit without ever leaving the cold. Some unripe fruits that normally would ripen indoors, like sufficiently mature green tomatoes, may never ripen after being exposed to chilling temperatures for a few days. My first tomatoes turned mealy because of chilling injury.
Maintaining cool temperatures in a modern house is no easy feat, even in the basement. If your basement stays 60°F or below, you're very lucky. You have an exceptional place to hold lots of things. Unfortunately, most heated basements these days are a dry 70°F, unsuitable for vegetable storage. Home refrigerators generally run between 35°F and 40°F, but since this varies greatly, it would be wise to use a small thermometer to check.
posted in: Preserving (Canning, Drying, Freezing)