Water Activity

Water activity (Aw) is the dimensionless difference between the sample water’s vapour pressure (P) and the pure water’s vapour pressure (P0) at the same temperature. The water’s thermodynamic energy condition in the system is indicated by the water activity level, which varies from 0 to 1.00. This value can alternatively be determined using the equilibrium relative humidity (ERH), which in a closed system varies from 0% to 100%, of the headspace above the sample.

In particular, in industries like food, pharmaceuticals, cannabis, and cosmetics, water activity plays a crucial role in guaranteeing the safety, quality, and shelf life of diverse items. It’s crucial to monitor and manage water activity for several reasons:

Development and expansion of bacteria:

Water activity affects the amount of water that is available for microbial growth. Controlling water activity lowers the likelihood of food spoiling and possible foodborne illnesses by limiting the growth of dangerous bacteria.

Water activity alters the physical and sensory characteristics of items, including their texture, colour, odour, and flavour. In order to maintain the desired texture, colour, odour, and flavour and ensure product consistency and customer satisfaction, water activity can be managed.

Moisture that migrates:

Water activity affects how moisture moves inside things. Inappropriate moisture migration can result in product deterioration and quality problems, which can be avoided with proper water activity management.

Controlling water activity prevents clumps and cakes from forming in powdered or granular products, guaranteeing homogeneity and user-friendliness.Chemical stability and reactivity: Water activity can affect the chemical stability and reactivity of formulations. Pharmaceuticals and other chemical items benefit from effective water activity control since it prolongs their shelf life and effectiveness.

Overall, observing and controlling water activity is an essential part of developing and producing products, ensuring their quality, stability, and safety throughout their stated shelf lives.

Modern tunable diode laser technology is used in the Infinita Lab equipment to measure the water activity of a sample in a temperature-controlled setting. Even the most difficult samples containing volatile substances, such as oils, sauces, cigarettes, spices, and alcohol, can be measured.

Moisture content or the precise amount of water in a sample is different from water activity. A water sorption isotherm curve can be used to investigate the connection between water activity and moisture content. Testing services for moisture content (loss on drying using oven drying or TGA methods) and the assessment of the water sorption isotherm using dynamic vapour sorption are also available from Infinita Lab in addition to testing for water activity.

Advantages

Reduced Microbiological Testing (Aw 0.60) may be used to support this.

Measures water molecules even when volatiles are present.

Considerations

25°C (Standard) for analysis and 15°C to 50°C (with additional calibration required)