(Designed for packers, cold-chain operators and retailers; shelf-life extension ≥ 14 days)

1. Background  
• China’s post-harvest fruit loss: 15–25 %, mainly dehydration, browning and fungal decay.  
• Conventional coatings (shellac or petroleum wax) are brittle, contain volatile organic compounds (VOCs) and face EU/US import restrictions.  
• Carnauba wax (E903) is a natural, food-grade wax extracted from Brazilian palm leaves. High melting point (82–86 °C), excellent gloss, fully edible and globally compliant.

2. Technical Objective  
Create a 8–12 µm semi-permeable edible film that:  
• Reduces water-vapor transmission rate (WVTR) to 40–60 g m⁻² day⁻¹  
• Maintains selective O₂/CO₂ exchange (internal O₂ 3–5 %, CO₂ 5–8 %)  
• Extends marketable life of citrus, apples, mangoes, avocados, stone fruit by ≥ 14 days at 4–8 °C, 85–90 % RH.

3. Coating Formulation  
(100 kg working solution; treats 10–12 t fruit)

| Ingredient                             | Function                          | Mass (kg) | Regulatory Note               
|---------------------------------------|----------------------------------|-----------|----------------------------------
| Carnauba wax, refined         | Primary film former          | 4.0       | E903, FCC, GB 1886.84       
| High-methoxyl pectin            | Thickener & anti-settling  | 0.3       | E440, GRAS                          
| Tween-80 (Polysorbate 80)   | Emulsifier (HLB 15)          | 0.4       | E433, < 10 mg kg⁻¹ residue    
| Potassium sorbate               | Antimould                          | 0.15     | E202, ≤ 200 mg kg⁻¹ in final fruit  
| Ascorbic acid                       | Browning inhibitor              | 0.2       | E300, GRAS                          
| Citric acid                             | pH adjuster / synergist      | 0.1       | E330, GRAS                          
| De-ionised water                  | Solvent                              | 94.85   | —                                         

Final solids 4.7 %; pH 3.9 ± 0.2; viscosity 25 °C: 40–60 cP.

4. Manufacturing Protocol  
Lab (1 L) → Pilot (100 L) → Plant (10 t)

Step 1: Melt carnauba wax at 90 °C under slow agitation.  
Step 2: At 65 °C add Tween-80, shear 3 000 rpm for 5 min.  
Step 3: Continuously shear at 10 000 rpm while adding aqueous phase (pectin, preservatives, acids, 65 °C) over 10 min.  
Step 4: Pass twice through high-pressure homogeniser at 55 °C, 30 MPa.  
Step 5: Filter through 100 µm mesh.  
Step 6: Cool to 25 °C.  
Final emulsion: off-white with bluish cast, mean droplet size 200–400 nm, zeta-potential −30 mV, stable ≥ 6 months at 5–25 °C.

5. Application Line (in-line or batch)  
a. Pre-treat: Sort, brush-wash, 100 ppm chlorine rinse, spin-dry (< 1 % surface moisture).  
b. Coating: Immerse 30 s or spray 2–3 bar, coverage 8–10 mL kg⁻¹ fruit.  
c. Drain: 20 s on perforated belt.  
d. Set: Warm air 45 °C, 60 s, then ambient 5 min.  
e. Pack: Return to 4 °C cold-chain; maintain 85–90 % RH.

6. Performance Data (independent lab, ‘Valencia’ oranges, 20 °C)  
Parameter | Control | Coated
--------------------------|---------|---------
Weight loss day-14 | 6.8 % | 2.3 %
Firmness retention | 78 % | 93 %
Decay incidence   | 12 % | 2 %
Internal O₂            | 21 % | 4.1 %
Internal CO₂         | 0.03 % | 6.2 %
Surface gloss (GU 60°) | 4.2 | 8.9

7. Regulatory & Labelling  
• Complies with EU 231/2012, US 21 CFR §184.1978, GB 2760.  
• Declarable as “coating (carnauba wax)” or “surface-treated with food-grade wax”.

8. Cost & Sustainability  
• Material cost: ~USD 0.22 per 10 kg fruit batch.  
• Zero VOC, water-based, no microplastics; wax is RSPO-certified sustainable.

9. Troubleshooting Quick Guide  
Observation → Cause → Fix  
• Cracking film → high solids → dilute to 4 %.  
• White bloom → cooling too slow → increase airflow 45 °C.  
• Off-flavor → over-dose sorbate → verify 150 ppm max residue.

10. Scale-Up Contacts  
Pilot tolling: 500 L batch available at Shanghai–Kunshan Food-Tech Park.  
Full plant design: 2 t h⁻¹ line (dip + dryer + UV-C) quoted at USD 180 k.

Ps.:The above information is for reference only. For detailed information, please consult the salesperson