1. Confirm Retort Effective Volume First
First check the effective working volume of your retort (not the total outer volume).
- Horizontal retort / vertical retort official parameter: marked as L or m³
- Conversion formula:1 m³ = 1000 L
This is the basic data for all loading calculations.
2. Standard Loading Ratio (Industry Universal Standard)
Recommended safe loading range for food sterilization:
- Optimal loading rate: 70% – 80%
- Maximum allowable loading rate: ≤ 90%
- Minimum loading rate: ≥ 5% (avoid small load effect)
3. Step-by-Step Calculation Formula
Formula 1: Calculate reasonable loading volume
Reasonable Loading Volume = Retort Effective Volume × Loading Rate
Formula 2: Calculate product weight per batch
Batch Loading Weight = Reasonable Loading Volume × Product Bulk Density
Simple Example
If retort effective volume: 1000L
- Optimal loading volume：
1000L × 70% = 700L 1000L × 80% = 800L
- Max loading volume：1000L × 90% = 900L
4. Different Product Bulk Density Reference
It is used to convert volume into actual loading weight.
- Vacuum pouch food (meat, snacks, braised food): ~0.7–0.8 kg/L
- Glass bottle / tin can products: ~1.0–1.2 kg/L
- Tray ready meals / soft containers: ~0.6–0.7 kg/L
- Sauce and liquid food: Do not exceed 2/3 of container single volume
5. Cage & Layer Frame Restriction Calculation
Most retorts use trolley and layer baskets for loading.
- Count total layers of the retort trolley
- Calculate the quantity of single layer placement
- Total batch quantity = Single layer quantity × Total layers
This method is more accurate for fixed specification products, directly controlling loading quantity to avoid overloading.
6. Core Calculation Principles & Notes
- Leave circulation gaps between products, layers and retort inner wall; gaps cannot be counted as loading space.
- Loading calculation must guarantee smooth circulation of hot water or steam to ensure uniform temperature.
- Do not only calculate weight; volume occupancy is the key factor affecting sterilization effect.
- When the product specification changes, recalculate the loading rate to prevent insufficient F value or overheating.