What Are the Methods for Determining Moisture in Food?

The Importance of Moisture in Food

Moisture is an essential component of food and a key factor in food processing. Moisture content, distribution and state greatly affect a food's structure, appearance, texture, flavor and freshness.
Water is a major cause of chemical change and microbial activity in food, directly affecting storage and safety. Measuring moisture content, distribution and state is therefore of great significance for moisture control, quality assurance and improved food safety.

Methods for Determining Moisture in Food

1、Direct Drying Method

Test Principle：The direct drying method applies to foods containing no or negligible volatile substances at101–105°C. Exploiting the physical properties of water in food, the sample is dried at 101–105°C under atmospheric pressure, and moisture content is calculated from the weight lost on drying, using weighings before and after drying.For example, the VicoMeterVM-E50rapid halogen moisture analyzer starts with one key press and quickly determines the moisture content of food.

Scope of Application: Vegetables, grains and their products, aquatic products, soy products, dairy products, meat products, braised dishes, grains, oils, starch, tea and other foods.

2、Reduced-Pressure Drying Method

Test Principle：The reduced-pressure drying method exploits the physical properties of water in food: at40–53 kPa, the sample is heated to 60°C ± 5°C and dried under reduced pressure to remove moisture, and moisture content is calculated from weighings before and after drying.

Scope of Application：This method suits foods that decompose, deteriorate or retain bound water at higher temperatures, such as syrup, fructose, MSG, high-fat foods, fruits, vegetables and their products.

3、Distillation Method

Test Principle：A water-immiscible organic solvent and the sample are heated together in a distillation moisture apparatus; the water in the sample evaporates with the solvent vapor, condenses in the condenser, and the sample's moisture content is obtained from the volume of water collected.

Scope of Application: Suitable for fruits, spices, seasonings, meat and meat products—foods high in both moisture and volatile components.

4、Karl Fischervolumetric

Test Principle：Based on the chemical reaction of iodine with water and sulfur dioxide, in the presence of pyridine and methanol, 1 mol of iodine reacts with only 1 mol of water. Karl Fischer moisture determination is divided into the coulometric and volumetric methods. In the volumetric method, iodine is added as a titrant of known concentration; the iodine consumed is calculated from the titrant volume used, giving the water content of the sample.

Scope of Application: Suitable for trace moisture determination in foods; not suitable for foods containing oxidants, reductants, alkaline oxides, hydroxides, carbonates or boric acid.

VicoMeter is an expert in moisture determination, rubber & plastics testing and petrochemical testing, offering reliable, easy-to-use rapid moisture analyzers, halogen moisture analyzers, Karl Fischer moisture analyzers, online moisture analyzers,DSC differential scanning calorimeters, HDT/Vicat softening point testers, melt flow indexers, impact testers and other analytical and inspection instruments. Whether for professional laboratory analysis, production workshops or rapid on-site testing, VicoMeter provides professional, targeted solutions meeting the quality control, production and in-line control needs of the chemical, pharmaceutical, plastics, food, lithium battery, petroleum, energy, paper, grain and research/education sectors.

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