The Chemistry of Meals, Ready-to-EatBY LOGAN VAN ELDIK

Summary

MRE, or also known as meal, ready to eat, are a quick alternative meal for soldiers that may be on the battlefield or elsewhere.

This combat ration was first adopted by the Department of Defense in 1975.

The soldiers nicknamed these as meals rejected by everyone and also materials resembling edibles.

Summary (continued)

During Operation Desert Storm, MREs were eaten by troops for far longer than they were originally intended. Originally intended for 10 days or less, many troops ate them for 60+ days.

As a result, three changes were quickly made to supplement the MREs and enhance their acceptability: shelf-stable bread in an MRE pouch was developed, a high-heat-stable chocolate bar was developed that wouldn't melt in the desert heat (this had been attempted before but the bar had a waxy taste and wasn't widely accepted), and flameless ration heaters were developed as a quick and easy method for troops to heat their entrees.

Summary Based on tests, 9 of the 12 entrées were replaced with new ones and the entree size was changed from 5oz. to 8oz. Commercial candies were added to 4 menus, hot sauce was added to 4 menus, and cold beverage bases were added to all 12 menus.

After further field testing and as a result of early feedback from Operation Desert Storm, even more changes were made starting with MRE X: commercial freeze-dried coffee replaced the old mil-spec spray-dried coffee, hot sauce was added to all 12 menus, wet pack fruit replaced dehydrated fruits, and commercial candy was included in 4 more menus (for a total of 8).

Finally the menu count rests at 24 to this very day.

Chemistry

The chemistry of meals, ready to eat comes from the flameless ration heater that is included to cook the meals.

A flameless ration heater is a water activated exothermic chemical heater used to cook the food. US military specifications for the heater require that it be capable of raising the temperature of an eight-ounce entree by 100°F in twelve minutes, and that it display no visible flame.

This heater is only able to work due to a strong chemical reaction within the heating package.

Chemistry The idea behind a flameless

heater is to use the oxidation of a metal to generate heat.

Magnesium metal works better than iron because it rusts much more quickly.

To make a flameless heater, magnesium dust is mixed with salt and a little iron dust in a thin, flexible pad about the size of a playing card.

To activate the heater, a soldier adds a little water.

Chemistry

When iron turns to rust, the oxidation process generates heat. But rust forms so slowly that the heat generated is unnoticeable. We are all familiar with much faster oxidation reactions as well. For example, when you "oxidize" the carbon atoms in a charcoal briquette, they get quite hot. We use the word burning to describe this high-speed sort of oxidation.

The equation Mg (s) + 2H2O (l) --------> Mg(OH)2 (s) + H2 (g) + 353kJ shows that the reaction of magnesium and water make magnesium hydroxide, hydrogen, and plenty of heat.

Works Cited

Brain, Marshall. "How MREs Work" 15 April 2003. HowStuffWorks.com.

<http://science.howstuffworks.com/mre.htm> 11 April 2013.

How Things Work: Meals Ready to Eat. N.p., 12 Sept. 2005. Web. 11 Apr. 2013.

<http://thetartan.org/2005/9/12/scitech/howthingswork_MREs>.

Chemistry Daily. N.p., n.d. Web. 12 Apr. 2013. <http://www.chemistrydaily.com/

chemistry/MRE>.