The world of food grade packaging films is a colorful and complicated one. There is no end to the options and variables. At the end of the day there are two main categories: Barrier and Non-Barrier films.
The simpler and less costly option of the two. While there are many different potential components, LLDPE linear low density polyethylene is probably the most prevalent. This material makes up most of the zip lock bags or trash bin liners films we purchase every day. LLDPE is a flexible material suitable for short term storage. Many 55lb bulk butter applications utilize LLDPE film, as well as cheese sold for processing within days of production.
Another matter entirely and can be a complicated subject. Barrier being the key word and references their ability to provide protection from oxygen and moisture. If you are looking to extend shelf life of retail products, or age many types of cheese, one key variable to your application will be barrier film.
Did you know that water activity is not the same thing as moisture content? According to the UC-Davis Dairy Research and Information Center: “Although moist foods are likely to have greater water activity than are dry foods, this is not always so; in fact a variety of foods may have exactly the same moisture content and yet have quite different water activities.”
This level of activity can have a significant impact on your product as: “Water in food which is not bound to food molecules can support the growth of bacteria, yeasts and molds (fungi). The term water activity (aw) refers to this unbound water.”
A common application of water activity measurement is the predicting of product shelf-life and stability especially in foods not relying on refrigerated storage. And for product that will ultimately be refrigerated, water activity measurement can be useful in production processes.
Monitoring and control of water activity in combination with pH and salt can effectively increase product safety and stability. With this in mind, if your lab does not currently test for water activity it may be helpful to add this useful tool to your SOP. To learn more about water activity click here for the full piece from UC-Davis or here for further information from Clemson University. Also, be sure to check out our water activity offerings from Nelson-Jameson by clicking here.