Food Moisture Testing Meaning and Method

Water is one of the indispensable substances for life activities, and moisture content testing is an important indicator for food analysis. The amount of moisture content in food is extremely important to ensure the quality of food. Control of food moisture content for maintaining the organoleptic properties of food, maintaining the balance of other components in the food, to ensure the stability of food are of great significance.

Forms of Water in Foods

Moisture in food exists in the form of both bound and unbound water. Bound water refers to crystallized water and adsorbed water, which are difficult to escape from the sample; unbound water includes wetting water, osmotic water and capillary water. This type of water is relatively easy to separate from the sample, usually in the food testing of moisture content is mainly unbound water. If the heating and drying time is prolonged without restriction in the determination of moisture, often the sample molecules will undergo certain chemical reactions, which will affect the results of the determination. Therefore, in the determination of moisture content must provide a certain temperature, time and operating conditions.

Methods of detecting moisture

1. Heat drying method:

Atmospheric pressure drying method (this method is widely used); 
Using a conventional drying oven, the sample is placed at a certain temperature to evaporate the moisture. Moisture evaporates more slowly at atmospheric pressure and is suitable for samples with high moisture content. A blast drying oven is used to provide uniform heating, and an electronic balance accurately weighs the change in mass of the sample before and after drying. This method is simple and economical, but may not separate out the bound water in the sample.