|International Vegetarian Union (IVU)|
32nd World Vegetarian Congress 1996
Fruits and Vegetables:
from EVU News, Issue 4 / 1996
The extraordinary diversity of common fruits and vegetables may become baffling when one must decide how to store them. Poor storage conditions may cause spoilage and/or loss of nutrients and/or disappointing flavour, but different foods crave different conditions! Just throwing everything into the refrigerator in paper bags isnít the best strategy.
Always remember that, in general, fruits (and tomatoes) DO NOT RIPEN under refrigeration! Putting fruits in cold storage before they are fully ripe will backfire.
Although 32°F (0°C) is a favourable spoilage-slowing temperature for most fruits and vegetables, some items donít do so well at 32° (0°C), and keep much better at 45° or 50° (7-10°C). For example:
Once these items get cut, bruised or frost-damaged, though, they are of course on a fast track toward rotting, so refrigeration then is a means for delaying the inevitable.
Warmer-still 55°-60° (13-15°C) temperatures are desired by (gas-producer) bananas; (gas-vulnerable) sweet potatoes; grapefruits and various tropical fruits; and ginger, pumpkins and winter squash, which are almost unique among vegetables in preferring dry, not humid, storage. Garlic (cold-lover) and onions (not fussy) go the dry route as well.
For most vegetables, preventing dehydration is crucial. It is helpful to set stem bases in cool water for a while before storage, and mist and sprinkle water on greens while they are air-exposed. You can combat the drying of foods that will be refrigerated by storing them in water-tight refrigerator compartments or plastic bags. (Do clean and re-use the bags!)
A potato peculiarity: Potatoes need dark storage, or else the skins and outermost flesh turn green. These green areas, like areas around sprouting eyes, are mildly toxic and taste horrible.
It has been a nutritional and economic blessing throughout human history that certain fruits and vegetables, when provided with their individually suitable storage conditions, will keep without spoiling for many months after harvest. Thus even in short-growing-season areas, a supply of some varieties of locally grown produce can be maintained all winter.
Long-storable vegetables emerged as staple foods in some cultures, as with potatoes in Ireland and parts of South America, sweet potatoes in some tropical areas, and many kinds of starchy tubers in the Caribbean. Other examples of "long-storage" crops include: carrots, beets, turnips, rutabagas, parsnips, daikon radish, onions and "root vegetables" in general; winter squashes; and apples and most pears. Foods among these which contain orange-to-deep-yellow flesh are important "winter vitamin A sources". Generally speaking, the root vegetables are useful sources of vitamin C unless seriously overcooked.
Preparation pointers are simpler than storage pointers! When fruit vegetables are prepared for raw use, always minimise the amount of time that cut surfaces are exposed to the air, to the light, and to warm temperatures. Protective cell walls have been broken, so nutrients are easily lost through dehydration or oxidation, and little defence remains against rotting or moulding. Prepare what will be used when it will be used, rather than create a stockpile for leftover use.
The heat of cooking causes dramatic loss of some vitamins, and other nutritional compromises. When cooking, use the minimum cooking temperature and time required to reach the texture and palatability youíre looking for (modest excess of either can also turn the texture to a repulsive mush).
Donít add acidic-pH ingredients (e.g. lemon, vinegar) before cooking because that prolongs texture-softening time, thus destroying more nutrients in the process.
Donít discard the cooking water, as large amounts of nutrients seep out into it! Use the least cooking water feasible, or else use no more liquid than you are willing to drink down in addition to the vegetables (whether used along with the cooked item, or creatively used for something else, such as a separate broth or sauce, etc.)
Baking root vegetables or winter squashes whole avoids water-related losses altogether. Frying or sautéing vegetables in oil raises other nutritional issues: The majority of calories coming out of the pan is from refined oil products, not from fresh vegetables. Thus a dish presumably chosen to add greater prominence to vegetables in the diet will actually add greater prominence to fat, to high-heat-refined and chemical-solvent-refined foods, and to fibre-free foods. One should consider this when deciding how much to fry.
Preparation hints could actually be summed up as: THINK FRESH! For greatest nutritional reward, eat fruits or vegetables in the freshest, closest-to-natural state possible.
Bob LeRoy holds an MS in Nutrition and Public Health, and an EdM
in Community Nutricion Education.