WATER ACTIVITY AND MOISTURE

Understanding Water Activity and Moisture Content for Optimal Hash Quality

While both water activity and moisture content influence hash quality, they represent distinct aspects of the water present in the product.

• Moisture Content: This is the total amount of water in the hash, typically expressed as a percentage of its weight. It's measured by drying a sample at a specific temperature and comparing the initial and final weights. Using a temperature that avoids evaporating volatile compounds besides water helps ensure accuracy.

• Water Activity (aw): This reflects the availability of water molecules for chemical, physical, and biological reactions. Water activity has a dimensionless value ranging from 0.0 (completely unavailable) to 1.0 (pure water).

Measuring Water Activity:

• Several methods exist for measuring water activity, each with its own advantages and disadvantages.

• Dew Point Method: Highly accurate but expensive and complex to operate.

• Capacitance Method: Simple, cost-effective, and suitable for hash. It measures changes in capacitance under varying humidity conditions. The AquaGauge by LeBrewtech.com utilizes this method. You can even 3D-print a container for your ULINE jars or other containers using a freely available file on Tinkercad.com (consider donating $20 to Hashcru to support my research).

Water activity plays a crucial role in several aspects of hash quality:

• Chemical Stability: High water activity accelerates reactions like oxidation, leading to color change and flavor degradation. Maintaining a water activity below 0.55 helps preserve the original character of the hash.

• Microbial Growth: Most microbes require a specific water activity level for growth (typically above 0.60). Storing hash at or below 0.55 minimizes the risk of mold and bacteria, preventing unpleasant flavors and toxins. Since bound water can become "free" over time, packaging at a lower level accounts for this potential increase.

Maintaining Optimal Water Activity:

• Regular Monitoring: Use a water activity meter to track your stored hash or rosin, ensuring it stays within the safe range (<0.55).

• Storage Temperature: Store hash between 0°C and 23°C for optimal stability. Choose a temperature that minimizes separation and maintains your desired texture.

Impact on Rosin Production:

• Higher water activity can affect rosin production:

• Heat Absorption: Free water can absorb heat from press plates, potentially reducing heat-related rosin degradation.  The higher end of the range for water activity typically produces lighter-colored rosin.

• Heating Efficiency: higher water activity allows for more even heating. 

Conclusion:

• Understanding both moisture content and water activity is crucial for maintaining optimal hash quality. Monitoring and controlling water activity helps preserve the unique characteristics, flavor, and shelf life of your hash.  $40 detailed SOP on using the LeBrew AquaGauge available.