What is the difference between moisture content and water content

Moisture content is probably the simplest value to understand. It is simply the quantity of water contained in a material.

Traditionally measured through loss of weight on drying. This method raises some issues, depending on the drying temperature you may not remove all water or may also remove other non water compounds. More modern methods resolve these issues and use infra red a bsorption. This way the water content is directly measured, the method is non-destructive and far quicker. Moisture content is typically given as a percentage in terms of weight.

Water Activity aW is a measure of the free water in a sample, and ranges between 0…1. Pure water would have an aW of 1. Interestingly Water Activity is related to Moisture Content but it is product and temperature specific. What is free water? Water can be bound in materials in two broad ways. Chemically Bound Water. Is bound so tightly that it cannot be utilised by bacteria, enzymes etc. It can be removed through high temperature heating.

Free Water. Is bound through weak bonds, structural diffusion, capillary condensation and surface binding. It can be utilised by bacteria and can exchange with the environment, it is also removed through heating. Generally, in the determination of the moisture content of a soil sample, we use heat treatment methods. These are called drying methods. For instance, oven dry method is where the soil sample is weighed before and after placing it in an oven at a particular temperature to observe the change in the weight.

The change in weight equals the amount of moisture present in the sample since, upon heating, we can assume all the moisture evolves from the sample. Water content is a parameter that can be used to describe the total amount of water present in a sample.

This parameter includes all the water in the vapour phase and the liquid phase. Therefore, the value of water content is usually higher than the moisture content. There are two major methods we can use to measure the water content. They are the direct method and the laboratory method. Contact Us. Search Kett. Search this site on Google Go! Product Lines. More Products. Other Instruments. Back to Top. Highly perishable fresh foods and canned fruits, vegetables, meat, fish, and milk. Salmonella, Vibrio parahaemolyticus, C.

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