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By: Zalina & Richelle

Freeze–Drying Foods. By: Zalina & Richelle. What is Freeze-Dried Foods?. Essentially, extracting all the water molecules from a food item Outcome is a product that can be kept in room temperature for a long period of time without spoilage . How Is Freeze Drying Food Done?.

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By: Zalina & Richelle

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  1. Freeze–Drying Foods By: Zalina & Richelle

  2. What is Freeze-Dried Foods? • Essentially, extracting all the water molecules from a food item • Outcome is a product that can be kept in room temperature for a long period of time without spoilage

  3. How Is Freeze Drying Food Done? • The food item is first cooled below a temperature of zero degrees Celsius • Placed into a bag or container which will keep air and moisture from reaching it • Then, the container is connected to a vacuum pump • The pump will extract the water molecules as they vaporize to establish the vapour pressure • All that is left, is the freeze-dried solid

  4. Benefits of Freeze Drying Foods • Can keep the original contents of the product: colour, texture, taste, size, and nutrients • Returns back into the same state when placed in water • Can keep it on a shelf at room temperature – freezer or cold storage not required • Mass is reduced, but there is no change in the volume • Lack of water reduces/eliminates the chance of bacteria • Any type of food or ingredient can be freeze-dried

  5. Who Uses It? • Hikers/Campers – lighter weight to carry • Dieticians • Pharmaceuticals – vaccines and injections – sealing material in bottle • Astronauts • Soldiers

  6. Why/When It’s Used? • Emergencies • Convenience • Long Trips

  7. Relation to Gas Law • Dalton’s Law • The total pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases. • Relation of Dalton’s Law and Freeze-Dried Foods • The water molecules establish the vapor pressure as they are vaporized by the vacuum pump from the food item. • This causes the foods to have a lower mass. • The mass of the food item is equal to sum of the vapor pressure, that is extracted from the food and the freeze-dried solid that is left behind.

  8. History of Food in Space • Eating in space for John Glenn turned out to be an easy though not too tasty experience. • Some experts were worried that the weightlessness in the food would be hard to swallow and as a result, collect in the throat, but John Glenn had no difficulty. • Other Mercury astronauts following John Glenn found the food unappetizing, had trouble rehydrating the freeze-dried foods, and disliked squeezing the tubes. • Today freeze-dried foods has become popular among astronauts

  9. Bibliography • Canham, Geoffrey. Chemistry 11 . Toronto, Ont.: Addison-Wesley Publishers, 2002. Print. • "Freeze-Dry Foods." Freeze-Dry Foods. N.p., n.d. Web. 5 Mar. 2011. <http://www.freeze-dry.com/biotech.html>. • "Lyophilization Freeze - Freeze - Dried Food." Inventors. N.p., n.d. Web. 6 Mar. 2011. <http://inventors.about.com/library/inventors/blfrdrfood.htm>. • "What is Freeze Drying?." wiseGEEK: clear answers for common questions. N.p., n.d. Web. 5 Mar. 2011. <http://www.wisegeek.com/what-is-freeze-drying.htm>.

  10. The End!

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