Freeze-dried to fresh-brewed, coffee and tea are manufactured in a variety of different ways.  Moisture has always been a thought in determining how long to dry or roast them.  However, measuring moisture alone in tea and coffee leaves much to be desired.  If a buyer of Ethopian coffee specifies green beans at 12% moisture, someone will probably check the shipment before it’s sent.  But how do they know that their 12% and their supplier’s 12% are equivalent?

A Better Moisture

Assessing the water activity of coffee and tea gives more accurate, usable results for two reasons.  First, water activity readings are based on already known standards, allowing two instruments on different continents to give related readings.  Secondly, products such as tea (1-2% moisture) have such low water levels in them that loss-on-drying methods are considerably imprecise.  If you normally reference moisture numbers, no problem.  The AquaLab Duo was designed to give you moisture and water activity from one sample in around 5 minutes.

Fighting Fungi

While most tea and coffee products are unable to support microbial growth, some are.  For example, in 2005, the EU adopted restrictions on ochratoxin A (OTA), a harmful mytoxin made by fungi that can grow on green coffee beans. Water activity can predict if ochratoxin A or other mycotoxins will be produced by the microorganisms growing on the coffee beans. There is no link between moisture levels and microbial growth – water activity alone is used for this application.