Jane asked: “What exactly are vine-ripe tomatoes? How are they different?”
There’s absolutely no better tomato than a perfectly red one that you pluck from the vine and eat while it’s still warm from the sun. Can you get close to that experience by buying the pretty tomatoes in the supermarket that are labeled “vine-ripened,” and maybe even still attached to their cute little length of stem?
Not really. Let’s look at some unfortunate facts.
When you hear the word vine-ripened, you naturally picture a tomato that’s redly hanging from the plant, ready to eat, at the moment when it is picked and rushed to the supermarket for your delectation. That mental image is why the phrase vine-ripened is so compelling! But that is not how these tomatoes are produced.
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There are essentially two ways that commercial tomatoes are harvested and ripened, and neither of them matches that image. Method one is to wait until the tomatoes have reached their full size – a stage of development known as mature green – and pick them then. The firm, lime-green tomatoes are treated with ethylene gas and sometimes other natural plant hormones, which cause them to ripen over the course of the next couple of weeks, turning soft and red and developing all the sweetness and flavor of a tomato.
Method two is what the industry calls vine ripe. These tomatoes are removed from the plant slightly later – sometimes with a length of vine intact – when they’re still hard and green, but have a faint first blush of pink: This is called the breaker stage. Picked at this stage, the tomatoes can be packed and shipped and, as long as they are kept at warm enough temperatures, they will ripen into red beauties without the need for added ethylene. They’re a little more delicate, so they are more expensive to pack and transport, but they can be sold for a premium price, thanks to that word “vine-ripened.”
At various times, I’ve bought and compared on-the-vine and ethylene-ripened tomatoes of the same variety and degree of ripeness. The presence of the green vine and stem on the former gives a nice tomato-vine smell when you unwrap them, that’s for sure. But in blind side-by-side tastings, my colleagues and I have never been able to consistently find a difference in flavor.
In fact, in scientific studies, judging panels have been unable to taste the difference between tomatoes that were picked green and ripened off the vine, and ones that were allowed to fully ripen on the plant and picked when completely red.
Conditions such as temperature during the weeks when the tomato is ripening from green to red make a difference, but whether the fruit is on or off the plant during those weeks really doesn’t seem to.
One often-cited reason why it doesn't matter whether the tomato is ripened on or off the vine is that, once the fruit is full-sized, it draws hardly any nutrition through its stem anyway, so the fruit is more or less indifferent to whether that stem is attached.
In the absence of my own sunny patch of tomato plants (a drawback of city life), I find that the seasonal heirloom tomatoes at my local farmer’s markets—varieties that are bred for flavor rather than durability and long storage—are the tastiest around.