Industries that range from food/perishables, to pharma, and personal care products, are required to comply with standards that are set by government agencies. These regulations ensure a prolonged shelf life of their products, as well as avoids or prevents unwanted chemical or physical changes to these products over time. The metric used to gauge these properties is called water activity. Water activity, which will be concisely defined below, is determined through water activity measurement devices, such as the Novasina Water Activity Meter.
Now do not confuse water activity with water content. Water content gauges how much water is contained in a product. Water activity (aw), speaks to the energy of the water sample. Both water content and water activity can be accurately measured.
Here is a scientific explanation for water activity. It is the amount of unbound water in a sample. Water that is not bound to or with a product’s ingredients can be utilized by undesirable microorganisms, which can lead to spoilage. Therefore, water activity is defined as a thermodynamic measurement of water that is expressed as the vapor pressure of water in a sample, divided by vapor pressure of pure water at a stated temperature.
If that is too technical a definition to get your head around, here is a ‘real life’ example that will immediately make more sense, as well as to underscore why your business needs to use the Novasina Water Activity Meter in your manufacturing and processing facilities.
Determining the Cause of Premature Food Spoilage
Walter is the quality control manager for “Good Times Baked Goods”, a leading pastry company.
Recently, Walter has been receiving complaints about his famous cupcakes spoiling well before their expiration date.
What is going on in Walter’s cupcakes?
Mold seems to be growing quickly on Walter’s cupcakes as a result of high water activity levels.
Water activity is the amount of unbound water present in the sample. In other words, some of the water molecules are chained to chemical groups in the product itself and are not available to move freely.
Water which is not bound to the ingredients themselves can be used by unwanted microorganisms, which could be one contributing factor to food spoilage.
Water activity is based on a scale of 0 to 1.0, with pure water having a value of 1.00. It is defined as the vapor pressure of water over a sample divided by the vapor pressure of pure water at the same temperature. In other words, the more unbound water we have, the more likelihood we have of microbial spoilage.
Unbound water will exert vapor pressure which can be used to determine microbial spoilage, chemical, and physical stability. In relation to cupcakes, a water activity measurement of 0.5 or lower would mean the likelihood of microbial growth is very low.
In Walter’s cupcakes, which measured at 0.78aw, it appears too many water molecules are unbound facilitating mold growth. If Walter had a Novasina Water Activity Meter, the water activity measurement device considered by many to be the industry standard, he would have known that the water activity level in his cupcake is too high and he could adjust his recipe to avoid any spoilage.
Walter’s Novasina Water Activity Meter is measuring the free water that can leave the product. It effectively detects this unbound water by measuring the equilibrium relative humidity over the surface. This value is then converted into a water activity measurement.
What makes a repeatable and accurate water activity measurement? In measuring water activity:
- Wait until the sample has reached stability.
- Measure at a consistent temperature so that you can compare values.
- Neutralize the influence of volatiles which can skew your results.
Walter is now measuring the water activity of his products on a regular basis and adjusting his recipes and method to keep the water activity level under control. He has been able to extend the shelf life of his products by far.
Novasina water activity meters are widely used in various industries such as food, pharma, personal care, and government agencies to help in prolonging the shelf life and to avoid unwanted chemical or physical changes to their products.
For more information, and to purchase your Novasina Water Activity Meter, contact us today.
