🎓 Water Activity: Controlling Moisture for Safety & Shelf Stability

🎓 Water Activity: Controlling Moisture for Safety & Shelf Stability

Introduction

Water activity (aᵥ) is one of the most misunderstood — yet crucial — quality controls in hemp-infused edibles, gummies, topicals, salves, and semi-solid formulations.

Water activity determines whether a product is:

  • Microbially safe
  • Shelf-stable
  • Oxidatively stable
  • Resistant to cannabinoid degradation

🧪 Water Activity vs Moisture Content

These are NOT the same:

Metric Measures Importance
Moisture Content (%) Total water Doesn’t indicate microbial risk
Water Activity (aᵥ) “Free” unbound water Determines microbial growth potential

Target: Keep aᵥ below 0.60 to inhibit pathogens.


🧫 Microbial Safety Thresholds

aᵥ Level Microbial Risk
0.90+ High (yeast, mold, bacteria)
0.70–0.85 Moderate
≤ 0.60 Safe Zone (no pathogenic growth)

This is why gummies, capsules, and topicals must maintain tight moisture control.


💧 Factors Affecting Water Activity

  • Humidity during processing
  • Hygroscopic ingredients (pectin, gelatin, sugars)
  • Packaging barrier efficacy
  • Temperature shifts
  • Residual solvents and oils

🧴 Water Activity in Product Types

  • Gummies: 0.55–0.60
  • Baked Goods: 0.70–0.75
  • Topicals: Below 0.60 for 18–24 month shelf life
  • Tinctures: No water activity concern

🧪 Testing Water Activity

Requires a chilled-mirror dew point water-activity meter (Aqualab, Rotronic).

Steps:

  1. Calibrate meter (0.25, 0.5, 0.75 aᵥ).
  2. Test product at production temperature.
  3. Repeat after 24 hours and during stability testing.

Summary

Proper water activity control extends shelf life, ensures safety, and protects cannabinoid integrity.

Explore stable hemp ingredients:

https://lowgravityhemp.com/collections/hemp-derived-ingrediants