Difference Between Freeze Dried and Dehydrated (With Table)

It is essential to preserve food to keep it fresh for a longer duration. In case fresh food items are not stored in compliance with the storage guidelines, they might become infected with microorganisms after some time. Therefore, preservation techniques like freeze drying and dehydration are quite significant for the food industry. Though the purpose is identical, they are quite different in terms of the preservation methodology employed.

Freeze Dried vs Dehydrated

The main difference between freeze dried and dehydrated is that the former is more reliable than the latter in terms of increasing the shelf life of a particular food item. Though they might sound similar due to the result, the steps involved in freeze drying and dehydration are opposite.

Freeze dried means preserving food by applying a very low temperature (close to the freezing point at times) and subsequently reducing the pressure. It is an industrial method that is quite successful in maintaining food quality for more than two decades at a stretch. It is a bit costlier than dehydration.

Dehydrated means food with reduced moisture content to increase its shelf life to a considerable extent. The etymology also favors the methodology applied during dehydration – “de” means removal, and “hydrate” means hydrous or innate water content. It can be performed in an easier way as no complex machinery is required for extracting moisture from commonly used eatables. It is also known as curing as it cures the quality.

Comparison Table Between Freeze Dried And Dehydrated

Parameters of ComparisonFreeze DriedDehydrated
Increase in Shelf LifeThe increase in the shelf is commendable, up to twenty-five yearsThe shelf life can only be increased up to ten or fifteen years
Other NamesIt is also known by two scientific terms – one is cryodesiccation while the other is lyophilizationCuring is the other general name for dehydration
Discovery of MethodThe process of freeze drying for discovered in modern times, around 1906Dehydration has been in practice for a long time and was first introduced in the fifteenth century
Temperature QuotientA lower temperature quotient is required for the process of freeze dryingThe process of dehydration can only be completed at relatively high temperatures
Applications in Food IndustryFood products like fruits and chocolates can easily be freeze driedFood products like fish and fresh vegetables can easily be dehydrated

What is Freeze Dried?

Freeze dried means passage of food through immense pressure and a relatively low temperature to seal the freshness for a long duration of time. The process is quite expensive and quick – food is completely frozen and then immediately subjected to a vacuum pressure which removes the ice residue by the process of sublimation.

The initial setup is a bit gruesome but the consistency makes it more reliable than any other type of food preservation method. It is essential because the cost-effectiveness is high – a small amount spent in the initial stages can lead to high-quality food preservation measures. There is no risk to the health of the consumer as no preservatives are added during the process.

Freeze drying finds application in upskilling the dry fruits industry and several chocolate manufacturing units, including raisins and other nuts. Ice creams are widely made using the process of freeze drying to reduce the reliance on synthetic preservatives.

What is Dehydrated?

Dehydrated means food that has been subjected to rigorous heating so that all the moisture is extracted, ultimately leading to preservation for up to fifteen years. Though it is more feasible than freeze drying, the addition of preservatives reduced its efficacy. The benefits of dehydration include low prices and easy storage.

It is essential because not all food industries can afford the setup for freeze drying. Dehydration is not possible unless the food is boiled or cooked partially. It is disregarded by health experts because the nutritional value is reduced as a result of subjection to high temperatures, even soaring to the boiling point. Evaporation also plays an essential role in this method, as a result of which the weight of the food items is also reduced considerably.

Once the food item is preserved, the method employed formerly can easily be determined from the remaining freshness and tenderness. Dehydration finds application in increasing the life span of leafy veggies and meat. Fish and other seafood can also be preserved using this reliable method.

Main Differences Between Freeze Dried And Dehydrated

  1. On freeze drying, the shelf life of the product is considerably enhanced for up to twenty-five years. Dehydration measures increase the shelf life up to one decade only.
  2. Freeze drying is also referred to as cryodesiccation and lyophilization for industrial usage while dehydrated food is simply regarded as cured food.
  3. As far as the discovery of food preservation methods is concerned, freeze drying was discovered after industrialization while dehydration dated back to ancient times when there were practically no refrigeration techniques available.
  4. The temperature is normally kept quite low for the process of freeze drying but a high temperature is necessary to bring dehydration into effect.
  5. The various applications of freeze drying include preserving chocolates and fruits. On the other hand, dehydration is suitable for fresh vegetables and non-vegetarian food products like fish.

Conclusion

Preservation of food items is not a recent development. With the advent of refrigeration measures, the old methods were discarded. It is believed by food experts that eatables with added preservatives do more harm than good. This proven fact increases the reliability of industrial food scientists on natural methods of preserving food. Pickling is also one of the most commonly used methods but its scope of application is quite limited.

Be it freeze drying or dehydration, the main criteria for assessing the reliability of the method remains the same. If the difference in quality between the original product and preserved product is low, then it is considered that the method employed in saving the food item is successful. The best way to utilize eatables is to consume them fresh (palatable) or when optimum preservation conditions like temperature and moisture somehow cease to exist.

References

  1. https://www.sciencedirect.com/science/article/pii/S0260877498000314
  2. https://journals.sagepub.com/doi/abs/10.1177/036354659202000521
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