Watermelon: a correction

Posted by kathryn in All In A Day's Work, Health News and Antioxidants

I’ve blogged before about lycopene, that lovely red carotenoid antioxidant. From everything I’ve read to date, foods containing lycopene have to be heated or processed for the antioxidant to become available to us. It’s one of the reasons I like this antioxidant, it puts paid to the whole “raw is best” argument. Raw is sometimes best, but not always and certainly not in the case of lycopene.

Or so I thought . . .

Three months ago I mentioned a report that the lycopene content of watermelon decreases if they’re stored in the fridge. Instead, kept at 21C they will continue to produce lycopene for at least two weeks after harvest, deepening in colour as they do so.

At the time I slightly dismissed the report, while it’s interesting, if we’re saying that lycopene has to be heated before it becomes bioavailable, then it’s presence or not in watermelon is a bit irrelevant.

It seems I was wrong. From reading Harold McGee’s Curious Cooks blog and then going to the original source (the article)) * in the Journal of Agriculture&Food Chemistry), it seems that raw watermelon is actually an excellent source of bioavailable lycopene. In fact studies show that raw watermelon juice has a similar lycopene bioavailability to heat-processed tomatoes. So, nutritionally, the best situation for watermelons is to be stored at 21C after harvest.

Unfortunately this doesn’t happen – after harvesting watermelons are refrigerated by farmers, transport companies, markets and retailers, to prolong their lifespan and simplify transportation. So what can you do to ensure the best lycopene content of the watermelon you buy?

• choose watermelons with bright red flesh, as they will have the highest lycopene content
• if you have a cool place in your house, store your watermelon there, rather than in the fridge
• eat your watermelon quickly after buying and only buy what you need

NB. The amount of betacarotene also increases in non-refrigerated watermelon – by up to 139%.

• Original article: Perkins-Veazie, P, Collins, JK, Carotenoid changes of intact watermelons after storage , J. Agric Food Chem, 54(16), 5868-5874, 2006.

11 November, 2006