The main difference between free water and bound water is that free water can be extracted with ease from food by methods such as cutting, pressing, or squeezing, whereas bound water cannot be extracted easily by such methods.
Water is present in the majority of areas around the world, in all living beings, and even in the food we consume. Most non-dehydrated natural food contain water up to 70% or more of their weight, and fruits and vegetables contain water up to 90% or more. Water is a great solvent for different molecules and biological molecules, a dispersing agent, a reactive chemical agent, and a medium for chemical reactions, which makes it an essential constituent in most of the food we consume.
Key Areas Covered
1. What is Free Water
– Definition, Extraction, and Features
2. What is Bound Water
– Definition, Extraction, and Features
3. Difference Between Free Water and Bound Water
– Comparison of Key Differences
Key Terms
Free Water, Bound Water
What is Free Water
Free water is water that can be easily obtained from foods by changing their structure and composition via cutting, squeezing, or pressing. This type of water remains within a matrix or in a gel. It is immobilized in capillaries or cells, but if released during cutting, squeezing, or damage, it flows freely. In fact, free water is similar to entrapped water. It is easily reachable. We can obtain free water from a component or source by partially changing the structure and composition of water or even without changing the structure and composition of the component.
Free water is not bound to inorganic compounds. There is less structural bonding in free water. Free water exists in the liquid state and is very much similar to liquid water. This type of water also acts as a solvent for certain chemicals. Free water is low in density and has a vapor pressure. In addition, it can freeze at moderate temperatures. Juice in fruits and vegetables such as oranges, watermelon, tomatoes, and lemons are examples of free water.
What is Bound Water
Bound water is water that cannot be easily obtained by changing the composition or structure of the source by methods such as squeezing, cutting, and pressing. Bound water is tightly bound to the compounds in food; hence we cannot easily remove it. Bound water is not a solvent and has a higher density than free water. Its freezing point is very low. It is lower than the freezing point of free water.
Bound water has more structural bonding than free water and liquid water. Extreme heat in deserts or freezing does not affect bound water negatively; hence the vegetation remains alive. This type of water has no vapor pressure. It’s impossible to extract this water even upon dehydration. Furthermore, water present in cacti and pine needles are examples of bound water.
Difference Between Free Water and Bound Water
Definition
Free water is water in food that can be obtained easily by changing the composition and structure of the food by pressing, squeezing, and cutting, whereas bound water is water in food that cannot be obtained easily by changing the composition and structure by pressing, squeezing, and cutting.
Density
While free water has a high density, bound water has a low density.
Freezing Point
The freezing point of free water lies in the range of moderate temperatures, whereas the freezing point of bound water is very low, even lower than liquid water and free water.
Extraction
The extraction of free water is easy, while the extraction of bound water is difficult.
Vapor Pressure
While free water has a vapor pressure, vapor has no vapor pressure.
Examples
Examples of free water are the water in fruits such as oranges, lemons, watermelons, and tomatoes, while examples of bound water are the water in cacti and pine tree needles.
Conclusion
In conclusion, we can categorize water in food into two categories: free water and bound water. Free water is the water we can obtain easily from food through cutting, pressing, and squeezing, while bound water is the water we cannot easily obtain from food. Therefore, this is the main difference between free water and bound water.
Reference:
1. “Water in Food Systems.” ePathshala.
2. “Free and bound water.” Food Science.
Image Courtesy:
1. “A Person Squeezing a Lemon in a Glass of Water” (CC0) via Pexels
2. “Water movement across membrane” By Connectivid-D – Own work (CC BY-SA 4.0) via Commons Wikimedia
Leave a Reply