AFTER HARVEST, IT’S STILL ALIVE!

Wait! Before you open your fridge, we’ve got news for you. Something inside is ALIVE! And it knows the best time for you to eat it! Don’t be afraid. It’s a beautiful thing! Scientists have recently found that many fruits and veggies are still alive even after they are harvested. And they know what time of day it is! And that’s good news! 

Photo: Courtesy of Diabetes News

New research from Rice University and the University of California at Davis reveals that your fruits and vegetables are not only alive, but they are continually changing their biology. They continue to respond to their environment, including temperature, light and dark, for days after they are picked, as they are “wired” for the circadian rhythms associated with the day/night cycle.

This is important!

According to a report recently published in Current Biology, fruits and vegetables change their levels of phytonutrients to correspond with lighting conditions. This affects their nutritional benefits as well as their anti-carcinogenic properties.

Photo: by Adam Fagan

It stems from the produce’s abilities to fend off pests and diseases, depending on the time of day they are most prevalent. Many plants begin ramping up production of insect-fighting chemicals a few hours before sunrise, the time that hungry insects begin to feed.

Building on the previous award-winning 2012 study of the ways that plants use their internal circadian clocks to defend themselves from insects, Janet Braam, professor and chair of Rice’s Department of Biochemistry and Cell Biology, study lead author Danielle Goodspeed, and their colleagues next studied cabbage.

Photo: Courtesy of Oregon Live

They placed some cabbages in simulated 12-hour-day-12-hour-night conditions, a process known as entrainment. They placed other cabbages in constant light and others in constant dark storage. Over several days, the cabbages were analyzed and exposed to known ravenous predators, cabbage looper larvae (Trichoplusia ni).

The researchers found that the entrained cabbages maintained their circadian rhythms and glucosinolate levels for up to a week after harvest. Correspondingly, they noted that the weight gain of the looper larvae that had fed on the entrained cabbages was half that of those that munched on leaves that were stored in either constant light or dark.

Photo: Courtesy of Lewis Ginter Botanical Garden

It makes sense that temperature matters too. The levels of the chemicals were reduced when the cabbages were stored at 22°C vs 4°C.

If you’ve ever experience jet lag, you’ve experienced human entrainment. Your internal circadian clock needs to reset itself to the day-night cycle in your new locale.

Photo: by Kenneth Moyle

Braam reported in Rice Unconventional Wisdom that the idea for the new research came from a conversation with her teenage son.

“I was telling him about the earlier work on Arabidopsis and insect resistance, and he said, ‘Well, I know what time of day I’ll eat my vegetables!’ That was my ‘aha!’ moment. He was thinking to avoid eating the vegetables when they would be accumulating the anti-insect chemicals, but I knew that some of those chemicals were known to be valuable metabolites for human health.”

These are chemicals that are among the most potent natural anti-cancer compounds known. This means we can time eating to when plants are most nutritious and protective for humans. Chemicals accumulate most midday, so lunchtime can be your healthiest meal of the day.

Photo: by Greg Emel

This phenomenon has also been observed by the researchers in mustard greens, spinach, lettuce, zucchini, carrots, sweet potatoes, squash, and blueberries.

Photo: by bmeabroad

So, it is important how we store our fruits and vegetables after we harvest them. Keeping them in a supermarket that is lit with bright lights or kept in storage in darkness 24 hours a day is a no-no. It is better to simulate day and night.

Photo: Courtesy Foodmatters

Photo: Courtesy of US Aid