Measurements of Equilibrium Moisture Content (EMC)
1. Hygroscopic Methods:
Static Equilibrium Method: The material is placed in a controlled environment (constant temperature and relative humidity) until no further weight change occurs.
Dynamic Method: The material is continuously exposed to a changing environment until equilibrium is reached, and the EMC is measured dynamically.
2. Gravimetric Methods:
Oven Drying: A sample is weighed, dried in an oven at a specified temperature until constant weight is achieved, and then reweighed. The difference gives the moisture content.
Desiccator Method: Similar to oven drying but uses a desiccator for removing moisture.
3. Electrical Methods:
Capacitance Sensors: Measure the dielectric constant, which changes with moisture content.
Resistive Sensors: Measure the electrical resistance, which varies with moisture content.
4. Chemical Methods:
Karl Fischer Titration: A chemical reaction method that measures water content in the sample.
Applications of Equilibrium Moisture Content
1. Food Industry:
Ensures products like cereals, dried fruits, and snacks have the right moisture content for optimal texture and shelf life.
Helps in preventing microbial growth and spoilage.
2. Pharmaceuticals:
Maintains the stability and efficacy of drugs by controlling moisture content in medicinal powders and tablets.
3. Agriculture:
Determines the right conditions for storing grains, seeds, and other produce to avoid spoilage and maintain quality.
4. Building Materials:
Assesses the moisture content in wood, concrete, and other materials to prevent structural damage and ensure proper curing.
5. Paper Industry:
Ensures the quality of paper products by maintaining the right moisture content during production and storage.