What is the Difference Between Drying and Dehydration

The main difference between drying and dehydration is that drying is a broader term that encompasses various methods of removing moisture from a substance, whereas dehydration is a specific form of drying that is typically more controlled and precise.

Drying and dehydration are two distinct processes used to reduce moisture content in substances. While they share the common goal of moisture removal, they differ in their applications and mechanisms.

Key Areas Covered

1. What is Drying
      – Definition, Features, Applications
2. What is Dehydration
      – Definition, Features, Applications 
3. Similarity Between Drying and Dehydration
      – Outline of Common Features
4. Difference Between Drying and Dehydration
      – Comparison of Key Differences
5. FAQ: Drying and Dehydration
      – Frequently Asked Questions

Key Terms

Drying, Dehydration

Difference Between Drying and Dehydration - Comparison Summary

What is Drying

Drying is a mass transfer process in which moisture is transferred from a wet or moist substance to the surrounding air or another medium, typically by evaporation. It is essential to reduce the moisture content to a level where the material becomes stable and resistant to microbial growth, enzymatic reactions, and physical degradation.

What are the basic principles of drying

The basic principles of drying include the following:

Heat Transfer: Drying relies on the application of heat to the moist material. This heat energy increases the kinetic energy of water molecules, causing them to change from a liquid state to vapor, thereby evaporating and leaving the material.

Mass Transfer: As water molecules are evaporated from the material, they are carried away by a flowing gas (usually air) or vapor. This mass transfer process is responsible for the removal of moisture.

Moisture Gradient: To maintain a continuous drying process, a moisture gradient needs to exist. This means that the wettest portion of the material is in contact with the drying medium, allowing for a continuous flow of moisture from the interior to the surface.

Drying vs Dehydration

Figure 1: Sun Drying

Drying has an important role in various industries. It is crucial for food preservation, where it extends the shelf life of edibles by removing moisture and preventing spoilage. In the pharmaceutical industry, drying ensures the stability and effectiveness of medications. Furthermore, agriculture benefits from drying in post-harvest storage, safeguarding crops against mold and pests. Drying also enhances material quality in manufacturing processes like ceramics, paper, textiles, and chemicals. Moreover, it aids in environmental control by reducing humidity, plays a vital role in biotechnology for preserving biological materials, and is essential for material handling in construction and manufacturing. Finally, drying is an efficient method in waste management to decrease the volume and weight of organic waste for easier disposal.

What is Dehydration

Dehydration reactions, as the name implies, are all about the removal of water molecules from a substance. This process can be categorized into two main types: intramolecular dehydration and intermolecular dehydration.

Intramolecular Dehydration

This type of dehydration occurs within a single molecule, typically a complex organic compound. It often leads to the formation of new chemical bonds and the removal of a water molecule.

Intermolecular Dehydration

In intermolecular dehydration, two or more molecules react with each other to eliminate water, resulting in the formation of a new compound.

Compare Drying and Dehydration

Figure 2: Dehydrated Strawberries

Dehydration reactions have a wide range of applications across various fields of chemistry. In the petroleum industry, dehydration processes are used to remove water and impurities from crude oil. This is essential for ensuring the quality and stability of the final petroleum products. Moreover, dehydration of alcohols is a common method for the synthesis of alkenes. In addition, dehydration reactions are crucial in the production of synthetic polymers like polyethylene, polypropylene, and polyvinyl chloride (PVC). These reactions link monomers together, forming long chains and resulting in diverse plastic materials.

Dehydration reactions are also involved in the synthesis and breakdown of complex carbohydrates, which are crucial for energy storage and cellular structure in living organisms. In biochemistry, dehydration reactions play a key role in peptide bond formation, where amino acids are linked together to form proteins.

Furthermore, dehydration reactions are often used in the synthesis of pharmaceutical compounds, allowing chemists to modify the structure of molecules to improve their properties. Dehydration reactions are also used to create various aromatic compounds and essential oils, which are essential in the flavor and fragrance industry.

Similarity Between Drying and Dehydration

  • Both drying and dehydration involve the removal of moisture or water content from a material or substance.

Difference Between Drying and Dehydration


Drying is a broader term that encompasses various methods of removing moisture from a substance, while dehydration is a specific and controlled form of drying.


Drying can be a more general and less controlled process, and it may not always result in complete moisture removal. The level of precision and control can vary depending on the specific method used. Dehydration is typically a more precise and controlled process. It aims for lower final moisture content and often involves specialized equipment and conditions to achieve this.

End Product      

In drying, the end product may still contain some residual moisture, whereas in dehydration, the product is typically fully dehydrated, with minimal water content.

FAQ: Drying and Dehydration

What is the main advantage of drying?

  • The main advantage of drying is the preservation and extension of the shelf life of various materials, particularly in food preservation and many industrial applications.

Is there a difference between dried and dehydrated fruit?

  • Yes, there is a difference between dried and dehydrated fruit. Dried fruit is a broader category that includes fruits that have been dried naturally or through various methods, including sun drying or air drying. Dehydrated fruit specifically refers to fruits that have been dried using a controlled heat source or dehydrator, typically at lower temperatures, to preserve more nutrients. Dehydrated fruit is a subset of dried fruit.

 What are the advantages of natural drying?

  • Natural drying methods are typically low-cost since they rely on freely available sunlight and air. It does not consume additional energy or produce greenhouse gas emissions, making it an eco-friendly option. Moreover, natural drying often involves lower temperatures than artificial drying methods.


Drying is a broader term that encompasses various methods of removing moisture from a substance, whereas dehydration is a specific form of drying that is typically more controlled and precise. Thus, this is the main difference between drying and dehydration.


1. “Food Dehydration.” Science Direct.
2. “Drying.” Wikipedia. Wikipedia Foundation.

Image Courtesy:

1. “Sun drying 070826-306 man” By Wie146 – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Dehydrated Strawberries” By (CC BY-NC-SA 2.0 DEED) via Flickr

About the Author: Hasini A

Hasini is a graduate of Applied Science with a strong background in forestry, environmental science, chemistry, and management science. She is an amateur photographer with a keen interest in exploring the wonders of nature and science.

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