Helping Foods Keep Their Cool (1/2)

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Before refrigerators, homes usually had ice boxes. But another way to keep food cool without the need for electricity is to use an evaporative cooler. This is easy to make and does not even use ice.

A common design is a tall box with food placed on several shelves inside. The shelves are pieces of metal with many small holes through them. The sides of the box are covered with pieces of thick cloth. Containers of water are placed at the top and bottom of the cooler. The ends of each piece of cloth lie in the water so the cloth stays wet.

Put the cooler in the open air but not in the sun. Air will pass through the wet cloth. The inside of the box will stay several degrees cooler than the outside air temperature. And this may be cool enough to keep foods fresh at least for a short time.

Cold storage in a freezer, however, can keep foods in good condition for months after the growing season. Yet foods can be damaged if they are kept too cold. The British development group Practical Action says the best way to prepare foods for storage is at harvest time while still in the field. Use a sharp knife to avoid damage.

参考译文：

有冰箱之前，家里通常都有冰盒。但另一种无需电力即可冷藏食物的方法是使用蒸发式冷却盒。这个盒子很容易做而且甚至不需要使用冰。

常见的一种是有几层隔层并放有食物的高盒子。隔层用具有许多小孔的金属板做成的。盒子侧面覆盖有厚布。在冷却盒的顶部和底部都放置装有水的容器。每块布的末端都浸入水中，这样可以使布保持湿润。

把冷却盒放于室外，但不要放在阳光下。空气将流经潮湿的布。盒子内部将保持比室外温度低几度。这样，足够冷的温度至少在短期内可以使食物保持新鲜。

但是，冷冻在冰箱中，可以使食物在生长季节后几个月中保持良好。然而，食物也可能被破坏如果它们被保存在过低的温度中。英国发展组织"实际行动"称，用于准备食物储藏最好的办法就是收获时在田里就进行储藏准备。用一把锋利的刀以避免破坏植物。

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