Purpose
Lyophilization (also known as Freeze Drying) is a dehydration process used as a preservation method amongst other things. For instance, there are many popular dehydrated foods, such as apple chips and instant coffee. In the food industry freeze drying is generally used in the preservation of perishable foods.
General Stages of Freeze Drying:
Pretreatment- products are pretreated to enhance freeze drying capabilities
Freezing
Sublimation of product
Transfer of vapor to Condenser
Vacuum release
The purpose of this experiment was to lyophilize our food sample, Peanut Butter and Jelly Poptart, and to prepare for bomb calorimetry.
Procedure
For Freeze Drying:
We placed our food sample into a 500 mL beaker, and grinded it using a spoon and spatula. This was to facilitate the freeze drying process. The grinded food was placed in a Ziploc bag, placed under freeze drying process for up to 72 hours.
Results and Conclusion
Wet weight: 52 grams
Dry weight: 49 grams
The product weighed less, indicating moisture extraction (3 grams of water), and looked more compact.
The product lasted us several weeks, owing to the freeze drying method. So Pop-Tarts is about 6% water.
Additional Resources:
Lyophilization (also known as Freeze Drying) is a dehydration process used as a preservation method amongst other things. For instance, there are many popular dehydrated foods, such as apple chips and instant coffee. In the food industry freeze drying is generally used in the preservation of perishable foods.
General Stages of Freeze Drying:
Pretreatment- products are pretreated to enhance freeze drying capabilities
- Examples include: increasing surface area, concentrating the product, decreasing vapor pressure, etc.
Freezing
- Product is cooled to temperatures below its eutectic point (typically between -50 and -80 degrees Celcius)
Sublimation of product
- The pressure is lowered and heat is applied to induce sublimation
- Application of a vacuum increases the rate of sublimation
Transfer of vapor to Condenser
- Temperature of the product increases and the remaining ice evaporates and ice condensor collects the evaporating product
Vacuum release
- Vacuum is broken with inert gas before sealing of material
The purpose of this experiment was to lyophilize our food sample, Peanut Butter and Jelly Poptart, and to prepare for bomb calorimetry.
Procedure
For Freeze Drying:
We placed our food sample into a 500 mL beaker, and grinded it using a spoon and spatula. This was to facilitate the freeze drying process. The grinded food was placed in a Ziploc bag, placed under freeze drying process for up to 72 hours.
Results and Conclusion
Wet weight: 52 grams
Dry weight: 49 grams
The product weighed less, indicating moisture extraction (3 grams of water), and looked more compact.
The product lasted us several weeks, owing to the freeze drying method. So Pop-Tarts is about 6% water.
Additional Resources: