Sometimes when we’re away from home, the power goes off and we never know about it. However, this can cause food stored in the freezer to defrost and deteriorate. To find out if these food items are as frozen as you left them, use this simple trick before leaving home: fill a cup with water, and put it in the freezer. When it’s frozen, place a coin on the top, and return it to the freezer.
If you find a coin at the bottom of the cup when you come back after a long vacation you should toss all the food immediately. It means that the power was out for enough time for your food to melt and re-freeze. If the coin is on top, it means that there was no power failure, and your food is as good as when it went into the freezer. If the coin is in the middle, it means that the power went out for a short period of time and most of your food items are probably still fresh.
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That's so simple, I can only wonder why I never thought of it myself; yet I never did. D'oh! I'll be doing it from now on, though. It's a good idea not just during a long vacation, but even if you're gone all day. Some freezers won't keep food frozen for that long.