Standard Operating Procedure (SOP) for Freeze-Drying Hash

Harvest Right Pharmaceutical Freeze Dryers

Purpose

To standardize the freeze-drying process for hash using Harvest Right pharmaceutical (Large) freeze dryers, maximizing terpene and cannabinoid retention, achieving consistent texture, and reducing drying time.

Scope

This procedure applies to all personnel responsible for processing hash into a dry, shelf-stable product for extraction or end-user consumption.

Equipment & Materials Needed

• Harvest Right Pharmaceutical Freeze Dryer (Large Model)
• Trays and Mesh Liners: For improved airflow and consistent drying
• Water-resistant gloves and PPE as necessary
• Silicone spatula or scraper: For spreading hash on trays
• Thermometer and hygrometer: To monitor conditions if necessary
• Desiccants: For post-drying storage

Procedure

1. Preparation of Hash for Freeze-Drying

• Water-to-Hash Ratio: The ideal water-to-hash ratio should be between 1:3 and 1:5. This ratio provides adequate moisture without oversaturating the hash, which helps maintain structure and reduces drying time.
• Layering on Trays:
  • Spread the wet hash evenly across the trays to a thickness of 1-3mm. Thin layering is essential for even moisture extraction and prevents the formation of wet spots.
  • Use of Mesh Liners: Place a fine mesh or perforated liner on the tray to allow airflow underneath the hash, enhancing sublimation and preventing condensation buildup. This can reduce drying time by up to 20%.

2. Initial Freezing Phase

• Place trays with hash in the Harvest Right freeze dryer and set the initial temperature to -40°C for at least 2 hours. This phase freezes the hash completely, locking in volatile compounds and preventing cell wall damage.

3. Primary Drying (Sublimation)

• Temperature: Set the freeze dryer to a temperature range between -25°C to -10°C. This temperature allows ice in the hash to sublimate without damaging the material.
• Duration: Run the sublimation phase for 12-24 hours. Periodically check the hash to ensure that sublimation is progressing uniformly across trays. Thicker layers may require additional time or adjustments in the drying cycle.

4. Secondary Drying (Desorption)

• Temperature Increase: Gradually increase the temperature to 5°C to 10°C for the secondary drying phase. This phase removes residual moisture left after sublimation, stabilizing the hash for storage.
• Duration: Continue this phase for an additional 6-12 hours, depending on the hash’s thickness and desired dryness. For thicker layers or particularly high-moisture batches, add 2-4 hours to ensure complete drying.

5. Final Drying Adjustments (Optional)

• If a firmer, more brittle texture is desired, extend the secondary drying phase by 2-4 hours.
• For a softer hash consistency, reduce the secondary drying time slightly. However, ensure no residual moisture remains, as this can affect shelf stability.

6. Post-Drying Storage and Handling

• Inspection: Check each tray for dryness by lightly pressing the hash. It should feel dry and crumbly without any moisture.
• Storage Preparation: Immediately transfer the dried hash to airtight containers with desiccants. Store in a cool, dark environment to preserve terpenes and prevent degradation.
• Handling: Handle with gloves to avoid contamination or moisture transfer from hands.

Additional Best Practices and Techniques from Industry Experts (e.g., The Press Club)

1. Optimized Layering and Tray Spacing:
   • Spread the hash in ultra-thin layers (preferably 1-2mm) to maximize airflow and reduce drying time. Use silicone spatulas to achieve an even spread.
   • Spacing Between Trays: If your freeze dryer allows, leave a small gap between trays to enhance airflow, further accelerating sublimation.
2. Temperature Control for Terpene Retention:
   • Maintaining a low sublimation temperature of around -25°C during the primary drying phase helps retain delicate terpenes.
   • Avoid high temperatures in the secondary drying phase, as terpenes can begin to volatilize at temperatures above 10°C.
3. Benefits of Mesh Liners and Tray Elevation:
   • Mesh liners not only improve airflow but also prevent the hash from adhering to the tray, making removal easier and preserving the hash’s structure.
   • Placing a slight elevation or spacer between the tray and hash layer allows more uniform cooling, which industry sources like The Press Club suggest enhances quality and consistency.
4. Environmental Control:
   • Freeze-drying in a room with stable humidity and temperature helps prevent moisture reabsorption during loading and unloading.
   • Ensure that the drying area remains clean and free of contaminants to maintain product purity.
5. Alternative Final Texture Settings:
   • For varying texture preferences, adjust final drying times based on client needs. Some users prefer a slightly softer product, while others prefer a fully brittle, powdery consistency.
   • Conduct periodic checks during the final drying stages to achieve the desired product characteristics.

Quality Assurance Checks

• Visual Inspection: Ensure that all batches are uniformly dry and free of residual moisture.
• Consistency Testing: Conduct regular texture checks to verify that each batch meets the desired specifications for moisture content and texture.
• Documentation: Record drying times, temperatures, and observations for each batch. This information aids in fine-tuning the process and provides a record for future improvements.

Safety and Compliance

• Personal Protective Equipment (PPE): Operators should wear gloves, lab coats, and other PPE to avoid contamination.
• Cleaning Protocols: After each batch, clean and sanitize the freeze dryer trays and any tools to maintain product purity.
• Compliance: Ensure that all freeze-dried products comply with industry standards for cleanliness, moisture content, and potency.