Freeze-drying and dehydration are two processes that remove moisture from food, but they differ in their procedures. Both methods offer different textures, colors, and shelf-life to the food. 

Process Of Freeze-Drying

Food slices are first frozen and then put for sublimation, in which all the ice is converted into vapors, and thus, around 99% of the water is removed from the food. In this way, nearly all of the moisture is removed from the food.

Process Of Dehydration 

Food slices are heated either by air drying or sun-drying. Oven drying is another method of dehydration. This method also removes most of the moisture from the food. But only around 95% of the moisture is removed from the food.

Benefits Of Freeze-Drying

1. As the food is dried at a very low temperature, that’s why most of the nutrients remain preserved in the food.
2. Freeze-drying is an efficient method of preserving heat-sensitive vitamins like vitamin C.
3. Freeze-dried foods can last more than 20-25 years, but only if they are stored the right way. They need to be kept in airtight containers, like vacuum-sealed jars or bags, to stay fresh for a long time.
4. Such foods are lightweight as almost all of the moisture has been removed. This makes them ideal to be carried during long-distance travel.
5. These foods taste just like the fresh ones and get rehydrated easily.
6. Some of the foods that are ideal for freeze-drying are – coffee, soups, fruits, etc.
7. This process helps in storing large quantities of food like fruits and vegetables for over a long period of time, so that, they can be used immediately at the time of their scarcity.

Disadvantages Of Freeze-Drying

1. The cost of freeze-drying foods is often more expensive for dehydration because of the complicated process involved.
2. Energy consumption is higher in freeze-drying because first the food is frozen and then subjected to a vacuum to remove moisture.
3. Food becomes crumbly in texture and due to this, it is more prone to destruction during storage and transport.
4. Food requires sensible storage like vacuum packaging with some sort of oxygen scavengers.
5. Foods that are high in fat, are not well suited for freeze-drying because fat does not sublimate.

Benefits Of Dehydration

1. The process of dehydration can be done using air-drying, sun-drying, or oven-drying.
2. This process removes up to 95% of the moisture from the foods.
3. These foods take some more time as compared to freeze-dried foods to get rehydrated again.
4. The shelf-life of these foods is around 4-5 years, but this also depends upon the storage conditions of the food. Dehydrated food needs to be stored in an air-tight container.
5. The weight of dehydrated foods is slightly more as compared to freeze-dried foods because of the slightly more moisture content retained even after dehydration.
6. It is a cheaper process of preserving foods at home.

Disadvantages Of Dehydration

1. More time is consumed in this process as compared to freeze-drying.
2. Foods often shrink during this process and become chewy and dry.
3. Dehydrated foods lose some nutrients, especially the heat-sensitive ones.
4. The taste of the food is altered a little bit due to dehydration at high temperatures.

process of freeze-dried pumpkin used in sproutling’s pumpkin khichdi

Sprouting offers baby products, which are nutritious and very similar to fresh foods due to the process of freeze drying used in their packaging and storage. Here, we are describing the step-by-step process that is followed at sproutling for making pumpkin khichdi.

• Step 1: Take 100 grams of pumpkin.
• Step 2: The pumpkin is now peeled.
• Step 3: This peeled pumpkin is washed.
• Step 4: After being washed, pumpkin is diced into thin slices.
• Step 5: These slices of pumpkin are spread out evenly over a baking tray.
• Step 6: The tray with pumpkin slices is subjected to freeze drying in the sproutling’s freeze drying apparatus.
• Step 7: Now, after some adjustments of time and temperature, the pumpkin is now ready for freeze drying.
• Step 8: After the procedure is completed, the freeze-dried pumpkin slices are taken out.
• Step 9: A fine powder of this freeze-dried pumpkin is made.
• Step 10: This freeze-dried pumpkin powder is then mixed with the frozen rice and lentil powder.

The best part of freeze drying is that you don’t need any preservatives for increasing the shelf life of the product and after hydration, the product is similar in taste and texture as that of the fresh ones.

Conclusion

Freeze-drying and dehydration are effective methods of preserving food, each with its advantages and drawbacks. Freeze-drying excels in retaining nutrients, shelf life, and flavor, making it ideal for long-term storage and lightweight travel needs. However, it comes with a higher cost and energy usage. Dehydration, on the other hand, is more affordable and easier to do at home, though it results in a shorter shelf life and some loss of nutrients and texture.

Ultimately, the choice between freeze-drying and dehydration depends on your priorities—whether it’s cost, storage duration, or nutritional preservation. Both methods help reduce food waste and ensure a steady supply of preserved food for future use.