普特英語(yǔ)聽(tīng)力網(wǎng):如何挑選到美味的番茄
時(shí)間:2013-03-07 15:48:00 來(lái)源:無(wú)憂(yōu)考網(wǎng) [字體:小 中 大]How To Find A Tasty Tomato
Most of us have had the same experience. We see a big, red tomato in the grocery store, take it home for our salad, and find out that it tastes like cardboard.
You might think that the tomato is sub-par because it’s been picked before it ripened, or shipped across the country. Those things can be true, but scientists have found another reason why modern tomatoes have little or no taste. It’s in their genes.
The problem began with old fashioned or heirloom tomatoes. They didn’t ripen consistently. Some areas would be red, while other areas, usually near the stem, would be white or green. About seventy years ago, tomato breeders accidentally discovered a variety that turned red uniformly. Consumers liked the way the tomatoes looked, and companies that made ketchup and tomato sauce could make better looking products.
The trouble was, red did not equal tasty.
While experimenting with weed genes that turned tomatoes dark green, geneticists accidentally discovered one of the reasons why today’s tomatoes lack taste. Modern tomatoes are light green before they turn uniformly red. Surprisingly, the mutation that gives tomatoes uniform red color actually disables some of the ripening genes. Those genes allow the fruit to make its own sugar which makes the tomato sweeter. The genes also increase the amount of carotenoid pigments, which give tomatoes the red color.
When researchers turned the ripening genes back on, their experimental tomatoes had twenty percent more sugar and up to thirty percent more carotenoids.
Unfortunately, regulations prohibited researchers from tasting their experimental fruits, but you can try eating heirloom tomatoes. They aren’t as pretty looking, but are tastier.