HOW TOMATOES LOST THEIR TASTE: Do you want your tomatoes to taste good or look pretty? That turns out to be a big question. Scientists have discovered that supermarket tomatoes often have a genetic mutation that reduces sugar and other tasty compounds in fruit. Small-farm tomatoes and heirloom tomatoes don't have that mutation. It seems that shoppers tend to choose tomatoes that are uniformly bright red. Big growers worked so hard to make their tomatoes red all over that they bred the taste right out of them!
Here's the science: Tomatoes that have not yet ripened on the vine are darker green at the top, near the stem. That dark green top allows the tomato to draw more energy from sunlight. The energy is stored as a starch. As the fruit ripens, the starches are converted to sugars, which taste good. Mass-produced tomatoes that haven't yet ripened are light green all over, so they absorb less sunlight while growing.