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:
- Calibrate meter (0.25, 0.5, 0.75 aᵥ).
- Test product at production temperature.
- 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