Fly rooms – the place where fruit fly researchers search for virgins and freaks – around the United States have two things in common: fruit flies and NPR. Thus, I heard the craziest science segment I’ve heard in a long time. You know those cabbages at the grocery store? Those heads of cabbage that always seem to always make way too much coleslaw? Even though they’ve been harvested, shipped and chucked onto the sprinkling grocery shelf, they’re aliiiiiive.
Individual parts of a plant can continue aspects of their metabolism when separated from the parent plant. A lab at Rice University wondered whether this might be the case with harvested fruits and vegetables (like those at the supermarket). Plants have a circadian clock (not surprising for a plant that relies on light for photosynthesis) and different metabolic activities fluctuate according to the time of day or night. For example, during the day when bugs like to feast on cabbage plants, cabbages tend to make more glucosinolates which repel the bugs.
To see whether grocery store cabbage maintained some metabolism after harvest the Braam lab exposed them to a light/dark regimen (12 hours light, 12 hours dark) helping the cabbage to regain its natural daily rhythm. Then they took samples of leaves at several times throughout the day and night periods to see whether certain metabolites fluctuated with a daily rhythm. And they did! The cabbages entrained to the light dark cycle and their metabolism fluctuated accordingly. The cabbages made more glucosinolates during the day and when leaves were given to cabbage pests to munch, they preferred those that were not in the midst of the “daylight” part of the daily cycle.
Whoa. I thought this was really cool and it actually might be a way to make vegetables more “nutritious”. Many of these fluctuating compounds are anti-oxidants and other beneficial molecules that we need to acquire from our diet. It’s possible that modifying storage and transportation facilities to have a light dark cycle, could improve the levels of beneficial molecules in vegetables (even in refrigeration). It seems like a wacky idea, but any bit of extra nutrition we can extract from the food supply is a good thing.