Wednesday, July 10, 2013

It’s Alive! Fruits and Veggies Don’t Have to Be On the Vine to Live


Research showed that cabbage still responded to light patterns after a week on the shelf.
Research showed that cabbage still responded to light
patterns after a week on the shelf.
Image: Shutterstock

Think those fruits and veggies on the grocery store shelves have already died? Think again.  Two studies out of Rice University from researcher Janet Braam and company have shown that not only do fruits and vegetables change their physiology in line with circadian rhythms, but they also continue to do so even after being picked.

Circadian rhythms are, essentially, our biological clocks. Our brains and bodies respond to the oscillation of the circadian rhythm, which is on a 24-hour clock. Changes in the circadian rhythm determine when our sleep drive is greatest, when we are hungriest, signals hormone production, and more. Circadian rhythm is strongly linked to the light-dark cycle of the day, and can even be affected by external signals like exercise. All living beings—humans, plants, animals, and even fungi—have a circadian rhythm.

Blueberries and other produce continued to produce  glucosinolate to deter pests, even after being picked.
Blueberries and other produce continued to produce
glucosinolate to deter pests, even after being picked.
Image: Shutterstock
Braam and her colleagues previously found that the nutritional content of produce changed throughout the day, based on where the plant was in its circadian rhythm cycle. The researchers also found that many fruits and vegetables had increased natural pest defenses during the day, which helped to repel insects without the use of pesticides.

That was the first study. The second study, more recently completed by the team, asked the question of whether the circadian rhythm changes still happened after fruits and vegetables were picked from their mother plant. The results? Braam and her team found that many fruits and vegetables do still respond to light and circadian rhythm for up to a week after being picked.

Cabbage, when kept in an alternating cycle of light (12 hours) and dark (12 hours), continued to produce glucosinolate, which is a compound that discourages pests like caterpillars. According to Time, the researchers completed the test on several other fruits and vegetables, such as lettuce, spinach, zucchini, sweet potatoes, carrots, and blueberries—and the results were the same.

The ever-changing physiology makes eating ripe produce key to gaining many health benefits.
The ever-changing physiology makes eating ripe produce
key to gaining many health benefits.
Image: Shutterstock
Because produce continues to change its physiology even after being picked, that makes consuming in season and ripe fruits and vegetables even more important. If you want to reap all the benefits of fresh produce, such as anti-cancer and other health-promoting effects, then you’ll want to harvest or purchase at just the right time. Eating out of season or unripe produce will result in less nutritional value and fewer positive health effects.

But when, exactly is the pinnacle of fruits’ and veggies’ freshness? That will likely require more research. 
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