How robust are blueberry antioxidants?

December 2, 2007 1:52 PM

Does cooking rob blueberries of their anti-oxidizing powers? How about freezing?

We hear about various fruits & veggies' anti-oxidizing wonderfulness, they say "blueberries rank #1 in antioxidant activity" -- buit is that true after they've been cooked into a muffin, or a pancake? How about the blueberries in my favorite Double Rainbow ice cream, from Trader Joes?

posted by Rash to Food & Drink (6 answers total)

Boiling foods significantly reduces the antioxidant content. Freezing is OK, but if you blanch them before freezing you have just boiled them. Steaming is apparently OK. Pressure cooking may be OK. Just baking them into a muffin, without otherwise boiling them, is probably OK. There are a lot of studies on this though -- google cooking and antioxidants.
posted by ubiquity at 2:24 PM on December 2, 2007

Blueberries freeze extremely well. I recently watched an episode of Good Eats about blueberries (transcript) in which Alton Brown recommended that you lay them out on a cookie sheet lined with aluminum foil when you first freeze them (to lessen the effects of freezer burn) and then when they're frozen, move them to a freezer bag (to keep them from tasting like everything else in your freezer).
posted by ErWenn at 5:38 PM on December 2, 2007

Raw foodists, who believe that cooking food destroys its nutritional value, will eat frozen desserts, provided the purees in the ice cream weren't cooked prior to freezing. Anecdotal, but that would suggest to me that freezing is less detrimental.
posted by melissam at 6:14 PM on December 2, 2007

Freezing tends to preserve complex molecules like antioxidants, heating tends to destroy them, relative to storing them at room temp.
posted by Mr. Gunn at 7:13 PM on December 2, 2007

Forgot to add that as the blueberry compounds oxidize(and therefore become useless as an antioxidant), they will generally change color, so that's how you'll be able to tell.
posted by Mr. Gunn at 7:17 PM on December 2, 2007

Heating tends to destroy some antioxidants (like vitamin C), but not others. Carotene is actually better absorbed when carrots are cooked, for example. The same goes for the health promoting compounds in tomatoes (e.g. lycopene): they are better absorbed in tomato sauce or paste than in fresh raw tomatoes.

See here for an overview of the effect of preparation methods on nutrient contents for selected foods.

All storage methods lose some nutrients, but freezing is by far the best. Commercially frozen blueberries may even provide more antioxidants than fresh blueberries that you buy in the store, since the frozen ones where frozen immediately after harvest and frozen very rapidly in order to preserve taste and nutrients.

There are still antioxidants in your muffins and pancakes, but I am unsure if they neutralize the effect of the sugar and the white flours.
Generally, most antioxidants will be best absorbed if you blend the raw or frozen foods. Enjoy a kale-blueberry smoothie!
posted by davar at 2:57 AM on December 3, 2007