Introduction

Shelf stability isn’t just a finishing step — it’s one of the most important parts of hemp product manufacturing. Whether you’re producing gummies, chocolates, soft gels, topicals, or functional edibles, water activity (aᵥ) plays a critical role in determining how long your products stay fresh, safe, and potent.

Unlike total moisture content, which simply measures how much water is present, water activity tells you how much water is available for microbial growth, chemical reactions, and cannabinoid degradation.

Understanding and controlling aᵥ is one of the easiest ways to improve product stability — and one of the most overlooked.

⚗️ The Science of Water Activity (aᵥ)

What Water Activity Actually Measures

Water activity measures the amount of free (unbound) water in a product — the water that microorganisms and chemical reactions can use.

A food or topical can have high moisture but low water activity if most of the water is “locked up” by sugars, salts, fats, or polymers.

The Critical Threshold

To inhibit harmful microbes (mold, yeast, bacteria), manufacturers aim for:

📉 aᵥ ≤ 0.60

At or below this threshold:

• Pathogens cannot grow

• Mold cannot colonize

• Yeast remains inactive

• COAs remain stable

Products above 0.6 require stronger preservation strategies or cold-chain storage.

Why Hemp Products Are Sensitive

Hemp infusions contain:

• Oils & lipids → prone to oxidation

• Active cannabinoids → degrade with heat, moisture, and light

• Plant compounds → sensitive to microbial shift

Combined with ingredients like fruit purees, gelatin, starches, butters, or waxes, water activity becomes a top priority for shelf life.

🧠 Why Water Activity Matters for Hemp Manufacturers

1. Prevents Microbial Growth

Low aᵥ suppresses:

• Mold

• Yeast

• Spoilage bacteria

• Toxin-producing organisms

This directly impacts the ability to pass:

• Microbial safety tests

• Total aerobic count

• Yeast & mold

• Pathogen panels

2. Protects Cannabinoid Potency

Moisture accelerates:

• Oxidation of cannabinoids

• Degradation into byproducts

• Terpene loss

• Rancidity in oils or emulsions

Proper aᵥ slows all of these reactions.

3. Extends Shelf Life

Maintaining the right water activity helps products remain:

• Potent

• Flavor stable

• Color stable

• Structurally intact

This is especially important for:

• Gummies

• Hard candies

• Chocolates

• Baked edibles

• Lotions and creams

4. Ensures Product Consistency

Retailers and consumers expect repeatable quality.

A controlled aᵥ means:

• Stable texture

• Predictable softening or hardening

• No sweating or blooming

• No microbial bloom over time

🍬 Category-by-Category Water Activity Guidelines

Gummies & Fruit Chews

Ideal aᵥ: 0.55–0.65

• Pectin and gelatin both bind water

• Sugars act as humectants

• Too low = overly hard

• Too high = microbial risk

Baked Goods

Ideal aᵥ: 0.65–0.75

• Shorter shelf life

• Require preservatives or refrigeration

• Cannabinoids can degrade faster in high-aᵥ foods

Chocolate & Confections

Ideal aᵥ: <0.50

• Very stable

• Fat matrix prevents moisture migration

Topicals (lotions, balms, creams)

Ideal aᵥ: <0.60

• Ensures microbial safety

• Prevents separation

• Maintains viscosity

Beverages (including emulsions)

Water activity not applicable — these rely on:

• pH control

• Preservatives (citric acid, sorbates)

• Pasteurization or aseptic processing

🧪 How to Measure Water Activity Correctly

Proper testing requires a chilled-mirror dew point water activity meter, such as:

• Aqualab

• Rotronic

• Pawkit

Steps:

1. Calibrate device with certified salts

2. Ensure sample is room temperature

3. Seal sample in chamber

4. Allow reading to equilibrate

5. Record aᵥ for batch documentation

Testing Points

Manufacturers should test:

• Pre-production samples

• Production batch samples

• End-of-run samples

• Retained samples during stability studies

🧴 Formulation & Manufacturing Tips

✔ Maintain Humidity-Controlled Rooms

Keep RH < 50% when:

• Curing gummies

• Cooling baked goods

• Filling topicals

• Packing edibles

High humidity ruins products faster than heat.

✔ Add Natural Preservatives

Consider:

• Citric acid

• Sodium citrate

• Potassium sorbate

• Tocopherols (vitamin E)

• Rosemary extract

These stabilize lipids and improve microbial safety.

✔ Use Proper Packaging

Packaging prevents moisture migration.

Best options:

• Heat-sealed pouches

• Glass jars

• Moisture-barrier liners

• Foil laminate bags

• Nitrogen flushing (optional)

✔ Vacuum Seal Bulk Ingredients

Bulk cannabinoids (isolates, gummies, distillate blends) can rehydrate from ambient moisture.
Vacuum sealing prevents spoilage and oxidation.

✔ Conduct Stability Studies

Store samples at:

• 25°C (ambient)

• 40°C (accelerated aging)

Test at:

• 30 days

• 60 days

• 90 days

This helps predict real-world shelf life.

🧠 Final Thoughts

Water activity is one of the simplest but most powerful tools for ensuring safety, potency, and shelf stability in hemp products.
From gummies to creams, controlling aᵥ keeps products fresh, compliant, and consistent — which is essential for retailers and consumers alike.

At Low Gravity Hemp, we supply ingredients that help manufacturers build products that stay stable longer, perform consistently, and pass COAs with confidence.

👉 Explore COA-verified ingredients designed for consistent formulation