Friday, April 16, 2010

Question of the Week: How many strawberries are in a box of cereal?

 "panning for gold" method of seperation
So I had a heated "discussion" with a good friend of mine the other day, the subject in question being how many strawberries are actually in a box of cereal featuring dried strawberries? In my limited experience, it's always been abysmally few pieces and so I told her i'd bet that there weren't more than 3 whole strawberries in a single box. She claimed her Kellog's Special K with Strawberries had way more than that (she also thot i meant strawberry pieces). So we made a bet! $10 to see who's right!

Being the thorough scientist (and apparently having nothing better to do) i went and bought a box to count the number of strawberries in it. I poured my first bowl and used the proper extraction tool (chopsticks) to remove the strawberry pieces. Hmmm...more than i thought, Special K definitely has more strawberry pieces than your typical strawberry-enhanced cereals. However, it turns out the concentration of strawberry pieces is higher on the top for some reason.

So how do we count how many strawberries are in it? You can't really count the pieces cause they're all different sizes and you can't compare volumes cause freeze-drying shrinks the fruit. The scientific method? by comparing Mass!

average weight of strawberry 23.573382g.

To make the result more applicable, i found the average weight of locally-available strawberries which were washed, salad-spun dried, and stem removed as if you would prepare them to eat with cereal. It was 528g for 14 strawberries = 37.714g each. They were rather large.

Strawberries are 91.67% water, meaning 8.3% other stuff.
Freeze-dry process typically leaves 1-4% water in the food product.

weight of 3 whole strawberries x (stuff%+water%) = weight of 3 freeze-dried strawberries (g)
113.14g   x   8.3%+1%  =   10.560g
113.14g   x   8.3%+2%  =   11.691g
113.14g   x   8.3%+3%  =   12.823g
113.14g   x   8.3%+4%  =   13.954g

So if the weight turns out lower than 10.56g then, there is definitely less than 3 strawberries. If the weight is greater than 13.95g then there is definitely more than 3 strawberries. Somewhere in the middle, means we can't tell for sure (and neither of us wins the bet).

Completely seperated from the cereal, i weighed the strawberries on a precision digital scale (in a university lab), taring for the ziplock bag weight of course!   Hmmm 18.4g, definitely more than 3 strawberries!

Note, once you open the bag, it's more accurate to remove all the strawberries in one go, cause they will start absorbing moisture from the air.  I used a ziplock freezer bag, the thicker plastic makes them gas-impermeable.

Conclusion: one box of Kellog's Special K with Strawberries cereal contains 4-5 whole strawberries (or 6-8 average strawberries). I guess that's not bad, but it's not a whole lot either. I think you're still always better off buying a container of strawberries and adding 2-3 to your bowl. But now you can calculate exactly how many strawberries there are and knowing is half the battle! maybe i should go out and purchase other brands of cereal just to see how many strawberries are in them for comparison...


Smruta said...

Interesting experiment! I wonder how applicable the "locally available" strawberries is in this method. What is locally available? Did you see where the cereal is manufactured and then get the weight of *those* locally available strawberries? What if those strawberries are smaller than the ones you have or bigger? :p

So, now the question is what happens to the cereals with nuts? :P

Monkey said...

As a consumer, you only have access to the cereal or local strawberries (in this case, from Dave's Market, the local grocery chain). So the comparison applies to the choice you make to buy cereal with strawberries or to buy fresh strawberries and add it to cereal yourself.

T said...

I trust that you found the largest "locally-grown" strawberries possible to maximize your chances of winning? ;)


Anya said...

Food nerd! =)