Tuesday, November 23, 2010

Calculating the True Price of Food: Starches Edition

Mashed potatoes, made from 100 grams
of potato and dehydrated potato
You're in the store and you see barley, rice, and pasta all with a relatively decent price. You start comparing prices to see which gets you the largest quantity for the least price, so you take out your calculator and start doing the math. But wait- you're missing an important part of the picture!
If you take one pound of rice, one pound of noodles, and one pound of barley, do you end up with only one pound of each type of the finished product? If not, do you end up with equal amounts of the finished product? How do you even know?

I had fun last night, performing a kitchen experiment, one of a few in a series which will follow. I bought a whole bunch of different starches, cooked 100 grams of each of them, and saw how many grams of end product I got for each food. With this, I've devised a table for you to figure out how much you're paying for your finished product, so you can do a more accurate price comparison in the store, to see which item is truly most worth your while to buy (nutrition factors aside).

The True Price of Starches

The contestants:
White flour macaroni
White rice
Brown rice
Pearl barley
White flour- made in three different ways- pancakes, tortillas, and pitas.
Sweet potatoes- made in two different ways- boiled, and baked.
Potatoes- made in four ways- boiled, boiled and mashed, baked, and french fried.
Instant mashed potatoes

The results:

Food Cooking method Start weight End weight Weight change Figuring out real cost per weight Example of true cost
White Rice Boiling w/ 2:1 ratio w/ water 100 240 240.00% Cost per dry weight divided by 2.4 Raw white rice at $1/lb really costs $0.42/lb of cooked rice.
Brown Rice Boiling w/ 2:1 ratio w/ water 100 200 200.00% Cost per dry weight divided by 2 Raw brown rice at $1/lb really costs $0.50/lb of cooked rice.
White Macaroni Boiled in water, strained 100 250 250.00% Cost per dry weightdivided by 2.5 Raw macaroni at $1/lb really costs $0.40/lb of cooked macaroni
Pearl Barley Boiled in water (until not chewy), strained 100 297 297.00% Cost per dry weight divided by 2.97 Raw barley at $1/lb really costs $0.34/lb of cooked barley
White Flour Tortillas Mixed w/ water, dry fried 100 130 130.00% Cost per dry weight divided by 1.3 White flour at $1/lb really costs $0.77/lb of tortillas
White Flour Pancakes Mixed w/ water, fried in sunflour oil 100 175 175.00% Cost per weight divided by 1.75 White flour at $1/lb really costs $0.57/lb of pancakes
White Flour Pitas Mixed w. water and 1 tsp yeast, dry fried 100 146 146.00% Cost per weight divided by 1.46 White flour at $1/lb really costs $0.68/lb of pita
Boiled Potatoes Boiled in water, strained 100 98 98.00% Cost per weight divided by .98 Potatoes at $1/lb really costs $1.02/lb of boiled potato
Baked Potatoes Baked in oven until soft 100 75 75.00% Cost per weight divided by .75 Potatoes at $1/lb really costs $1.33/lb of baked potatoes
French Fried Potatoes Fried in sunflower oil until golden 100 49 49.00% Cost per weight divided by .49 Potatoes at $1/lb really costs $2.04/lb of French Fries
Boiled Potatoes Mashed Boiled, then mashed, water added until creamy 100 129 129.00% Cost per weight divided by 1.29 Potatoes at $1/lb really costs $0.76/lb of mashed potatoes
Boiled Sweet Potato Boiled in water, strained 100 100 100.00% Cost per weight divided by 1 Sweet potatoes at $1/lb really costs $1/lb of boiled sweet potato
Baked Sweet Potato Baked until soft 100 60 60.00% Cost per weight divided by .6 Sweet potatoes at $1/lb really costs $1.67/lb of baked sweet potato
Instant Mashed Potatoes Water added until creamy 100 570 570.00% Cost per weight divided by 5.7 Instant mashed potatoes at $1/lb really costs $0.18/lb of ready mashed potatoes

All made from 100 grams of flour
Notes on the chart:
Water prices were not included, nor were oil prices for pancakes or French fries, which would up their price. 
For the pita, 1 teaspoon of bulk yeast was added, which cost less than a penny, so it wasn't added to the price.
No other things were added to the foods, no salt, no sugar, no spices, no eggs, no butter, no oil unless noted.
All the foods were prepared how they'd usually be prepared- the noodles were regular, not mushy. Rice was prepared with a 2:1 ratio of water to rice, as it usually is. The barley was cooked until it was not chewy, but not mushy. The potatoes were boiled until soft, but not falling apart. The baked potatoes and sweet potatoes were baked until they were soft, but not burnt.

Applying the results to our life:
If everything cost the same amount per pound, it would be easy to see that the cheapest choice of starch would be mashed potatoes, then barley, followed by macaroni and then white rice and brown rice. However, each product in the store has a different price.
Where I live, stores sell 500 gram bags of pasta for $0.82. First, you need to figure out the cost per pound or kilogram. This pasta costs $0.74 per pound.
Rice, on the other hand, comes in 1 kilogram bags for $1.37, which is $0.62 per pound.
Pearl barley costs $1.68 for a 500 gram bag, which is $1.53 per pound.
Brown rice costs $2.88 per kilogram, or $1.31 per pound.
White flour costs $0.69 per kilogram, or $0.31 per pound.

Just from the initial price, you'd assume that white flour is the cheapest starch, followed by white rice, then pasta, then brown rice, then barley.
But before we can be sure if that really is the order of cheapest to most expensive, we have to apply the numbers in the chart above.

To figure out the true price of pasta, you need to divide $0.74 by 2.5. With this conversion, you'd discover that the true price of the pasta is $0.30 per pound.
White rice you'd divide by 2.4 and get a total of $0.26 per pound.
Pearl barley would be divided by 2.97 and get $0.52 per pound.
Brown rice would be divided by 2 and get $0.65 per pound.
White flour, depending on what you're making, would either be $0.24 per pound (tortillas), $0.18 per pound (pancakes), or $0.21 (pitas).

It works out that the cheapest foods to make, in order, are pancakes, pitas, tortillas, white rice, pasta, pearl barley, then brown rice. While this is similar to the order if you hadn't done the calculations, you'd discover that brown rice is more expensive than pearl barley, even though, when dry, the barley looks more expensive.
You also discover that the price of white flour and rice are not that different, so if rice is on sale for $0.50 a pound, and the price of white flour goes up to $0.38 per pound, the real rice price would be $0.25 a pound, making it cheaper than the flour's $0.29 cents a pound tortillas, but still more expensive than the $0.22 cents a pound pancakes and just a tad cheaper than the $0.26 a pound pitas.

Mashed potatoes price comparisons would be as follows:
Assume that you bought the instant mashed potatoes, 400 grams for $2.65 at the local grocery store, or $3.01 per pound. Bought potatoes for $1.23 per kilogram, would be $0.55 per pound..
However, the real price of the mashed potatoes from fresh potatoes would be $0.43 per pound, and the instant mashed potatoes would be $0.53 per pound.
In such a case, the fresh mashed potatoes would be cheaper by a little.
However, I'm buying instant mashed potatoes in bulk for $1.42. The mashed potatoes made from the bulk bought stuff would be only $0.24 per pound, which is cheaper than the mashed potatoes made from the fresh stuff, as well as being cheaper than white rice, pasta, brown rice, and barley.

Of course, these numbers don't necessarily apply to you, but I hope that by showing you this process, you'll be able to figure out which starches are truly cheapest per pound where you live.

Water really makes the biggest difference in determining the final price of a food. Foods like barley and instant mashed potatoes that absorbed the most water during preparation end up being the most cost efficient. On the other end of the scale, foods like French fries and baked sweet potatoes that lose much of their water while cooking end up being the least cost efficient.
It may seem silly to factor water weight into figuring out the true cost of an item, but the fact of the matter is that water really makes our portions larger, which tricks us into thinking we're getting more food, which makes us end up being satisfied with less food. Case in point- while you can probably eat a whole bag of dehydrated apple chips, you probably won't find yourself eating more than one or two apples in one sitting.
Water both fools our minds and actually fills us up, so yes, water weight definitely is included when figuring out the true cost of a food.

Coming soon in this series:
Calculating the true price of beans
Calculating  the true price of proteins
Calculating the true price of cereals

Have you ever figured out the prices of different starches based on the finished product? Do you think calculating costs this way is accurate or not?
Would you use this chart to help you determine which starches are cheapest to buy where you live, or is it too complicated?


  1. This would be more useful if it took nutrition into account because even if white rice expands more making it cheaper than brown rice per prepared weight, it is more nutritious and needs less of any additional ingredients to make a complete meal.

  2. Hi How can I find your bean and protein chart please? Thanks. Marylise

  3. This seems like a really unhelpful chart. Weight is not important, calories are. In particular, raw white potatoes are only 69 kcal per 100g while raw white rice is 365 kcal per 100g. Kcal per dollar would be a more helpful comparison. Where I live (Canada) jasmine white rice from thailand is 1623 kcal per dollar, while white potatoes are only 786 kcal per dollar. Even though we grow the potatoes here in Canada, and the jasmine rice from thailand is some of the best stuff you can buy, the rice is double the efficiency per dollar. Not to mention sometimes the rice goes on sale for quite a discount and you can get it at a price that gives you 2656 kcal per dollar.

    So even though you end up with comparable masses of food, the caloric density is vastly different.

    1. Thats neat! Id love to hear more about that!

  4. Should have factor in nutrition density into the picture too.

  5. You are missing the point! This is strictly a cost per pound comparison. Nothing more! If you want nutrition or calories per cost there are other sites that will help out there. Don't leave negatively comments just because this isn't what you are looking for.

  6. Also missing the point but very important is prep time. Pasta is easy whereas delicious, smooth mashed potatoes (not those weird lumpy things with peels) are time consuming and require some skill. Ok, any cooking does but different skills.

    Just a thought from a chance reader.


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