From raw groundnut cleaning to cold-pressed or hot-pressed oil — complete technical guide with exact process parameters, equipment specifications, yield data, and aflatoxin management. Based on 50+ peanut oil plant installations across Africa and Asia.
Key numbers to understand before designing a peanut oil plant. Every parameter directly affects yield or quality.
Every stage is described with exact parameters, equipment models, and the technical reason each step matters to final yield and oil quality.
Raw peanuts arrive with 0.5–5% impurities: stones, soil clods, broken kernels, stems, and metallic debris from harvesting and transport. A three-machine cleaning system removes all foreign material before any heat or mechanical processing begins. Skipping this step causes accelerated screw press wear (stones abrade the barrel), safety hazards, and oil quality problems from soil contamination. Cleaning is the lowest-cost step with the highest consequential impact if omitted.
Peanut shells (hulls) account for 20–30% of whole peanut weight and contain essentially zero extractable oil. Pressing whole peanuts with shells dilutes the oil-bearing material, reducing effective oil content from 42–55% (kernel) to 30–35% (whole peanut) — a 25–35% reduction in achievable yield. Mechanical dehulling achieves 95%+ shell-kernel separation in a single pass. The separated shell fraction has commercial value: it can be sold as biomass fuel, cattle roughage, or composted as agricultural input, partially offsetting processing costs.
This stage determines the character of the final oil and is the primary route decision in peanut oil production:
Hot Press / Roasted Oil Route: A rotary drum roaster heats kernels to 160–180°C for 20–40 minutes. The Maillard reaction between amino acids and reducing sugars develops the characteristic roasted peanut aroma compounds (pyrazines, furanones). This aroma profile is highly valued in West African, Chinese, and Southeast Asian cooking markets. After roasting, kernels are cooled to 105–110°C moisture-adjustment temperature before pressing.
Cold Press / Virgin Oil Route: No roasting. Kernels are conditioned at 60–80°C maximum to adjust moisture only. The natural tocopherols (vitamin E), phytosterols, and light flavour compounds are fully preserved. Cold-pressed peanut oil commands 2–3× premium retail pricing in organic, health food, and European export markets. EU Cold Pressed certification requires temperature throughout the process to remain below 27°C; commercial operations typically work at <50°C for "cold pressed" labelling.
The screw oil press (expeller) is the mechanical heart of peanut oil production. A rotating helical screw shaft with progressive-pitch flights compresses kernels as they travel forward against a perforated barrel (cage). Pressure builds from approximately 20 MPa at the inlet to 35–50 MPa at the discharge choke. Oil is squeezed through the barrel slots (0.1–0.3 mm gaps) and collected in a trough below. The remaining fibrous cake (peanut meal) is expelled as a solid cake from the press choke end. Screw rotational speed is the key operating variable: higher RPM increases friction heat, compresses more aggressively, and achieves the hot press effect; lower RPM reduces heat for cold pressing.
Freshly pressed peanut oil contains 2–8% suspended fine particles: press fines (crushed kernel fragments), protein fragments, and fine fibre. These particles must be removed before filtration. Gravity settling in a cone-bottom tank at 40–60°C (above peanut oil solidification point) allows 80–90% of coarse particles to settle by gravity over 2–4 hours. The clarified oil is drawn from the top of the tank; the settled sludge at the bottom is collected and re-pressed or blended back into the input stream to recover residual oil. Settling before filter pressing significantly extends filter cloth life by reducing the solids load entering the filter press.
Plate-and-frame filter press clarifies crude peanut oil to food-grade clarity. Settled crude oil is pumped under pressure through a series of filter chambers, each lined with polypropylene filter cloth at 1–5 μm porosity. Suspended particles are captured on the cloth surface while clarified oil passes through. After each cycle (4–8 hours), the press is opened and filter cake is removed — this filter cake contains recovered oil and can be re-processed. Output oil has brilliant golden clarity and meets commercial food-grade suspended solids requirements. For cold-pressed premium oil sold at retail, filtration quality directly affects presentation and shelf appeal.
For crude natural peanut oil sold in premium/artisan markets (cold-pressed, natural groundnut oil), no refinery is required after filtration — the natural colour and flavour are part of the product value. For standard retail cooking oil competing with imported refined products, a full batch refinery removes colour, odour, and excess free fatty acids to produce neutral cooking oil meeting international food standards.
Degumming (D): Hot water at 3% v/v, 60–75°C. Hydrates and removes phospholipids. Not critical for peanut (low phospholipid) but improves subsequent steps.
Neutralizing (N): NaOH solution at 12–18°Bé (Baumé scale), 65–85°C. Reacts with free fatty acids to form soap (saponification). Soap is removed by centrifuge and warm-water washing (3× at 80°C). Reduces FFA from 1–3% to <0.2%.
Bleaching (B): 1–2% activated bleaching earth by weight of oil, at 95–105°C under vacuum (<70 mbar), 20–30 minutes contact time. Adsorbs colour pigments (carotenoids, chlorophyll residues), oxidation products, and — critically for peanut oil — reduces aflatoxin levels by 40–70%. Spent earth filtered off by leaf filter or plate press.
Deodorizing (D): The final and most critical refinery stage. Oil is heated to 220–250°C under high vacuum (2–5 mbar) with live steam injection (0.6–0.8% oil weight). This steam-strips volatile flavour and odour compounds (aldehydes, ketones, fatty acids) without thermally damaging the oil. Output: completely neutral colour, taste, and odour.
Industrial peanut oil processing plant showing screw oil presses in operation, golden peanut oil flowing into collection vessels, pressed peanut cake emerging, professional food processing factory photography, warm industrial lighting --ar 16:9
The method choice is primarily a market decision, not a technical one. Both produce high-quality oil — for different buyers.
Reject all visibly mouldy, shrivelled, discoloured, or insect-damaged peanuts before intake. Visual rejection alone is not sufficient for export compliance. Use rapid ELISA test kits (15-minute result, $2–5 per test) to screen every incoming truck load above threshold. Maintain supplier qualification records and require aflatoxin certificates from controlled-storage suppliers.
Aflatoxin is produced by fungi during storage, not only during growing. Store peanuts at moisture ≤9% (use moisture meter on every consignment), relative humidity <70%, temperature <20°C. Implement strict FIFO (first-in, first-out) rotation. Inspect storage bins monthly for pest damage, roof leaks, and ventilation failure. Fumonisin co-contamination risk increases in warm humid conditions.
Activated bleaching earth (clay) physically adsorbs aflatoxin molecules during the bleaching stage of refining, reducing aflatoxin levels by 40–70% per pass. This is why a refinery is critical for EU export compliance — raw material control alone cannot guarantee the required <2 μg/kg B1 limit. Increase bleaching earth dose to 2–3% for high-risk raw material batches. This makes the bleaching step a critical control point in the HACCP plan, not merely a quality step.
Test every production batch before dispatch using HPLC (high-performance liquid chromatography, laboratory standard) or ELISA immunoassay (on-site screening). Maintain batch testing records with result, lot number, date, and disposition decision. Positive test result: quarantine batch, re-test with HPLC, and either re-process through extended bleaching or reject. Keep minimum 6-month sample archive for traceability in the event of customer or regulatory claims.
Complete equipment schedule for a commercial 20 TPD peanut oil plant with optional batch refinery for retail-grade output.
| # | Equipment | Model | Qty | Capacity | Power (kW) | Stage |
|---|---|---|---|---|---|---|
| 1 | Vibrating Cleaning Screen | TQLZ80 | 1 | 8–12 TPH | 1.5 | Cleaning |
| 2 | Magnetic Separator | TCXT25 | 1 | 10 TPH | 0.75 | Cleaning |
| 3 | Destoner | TQSx series | 1 | 8 TPH | 1.1 | Cleaning |
| 4 | Peanut Dehulling Machine | BTM-800 | 2 | 8–10 TPD each | 7.5 | Dehulling |
| 5 | Rotary Drum Roaster | CYJ-2 (optional hot press) | 2 | 2T/batch | 5.5 | Roasting |
| 6 | Conditioning Cooker | Vertical steam conditioner | 1 | 25 TPD | 3.0 | Conditioning |
| 7 | Screw Oil Press | 6YL-180 | 3 | 8–10 TPD each | 22 | Pressing |
| 8 | Crude Oil Settling Tank | 5T carbon steel, cone bottom | 2 | 5T each | — | Settling |
| 9 | Plate & Frame Filter Press | BASY-500 | 2 | 5 TPD each | 2.2 | Filtration |
| 10 | Degumming / Neutralizing Vessel | DG-2000 (optional refinery) | 1 | 2T/batch | 3.0 | Refining |
| 11 | Bleaching Vessel | BL-2000 (optional refinery) | 1 | 2T/batch | 4.0 | Refining |
| 12 | Deodorizing Vessel + Vacuum System | DZ-2000 (optional refinery) | 1 | 2T/batch | 15.0 | Refining |
Note: Power figures are installed motor ratings. Actual average consumption is typically 60–70% of installed capacity. Total installed power for full plant (with refinery): approximately 65 kW. Daily energy consumption estimate: 150–180 kWh/tonne of refined oil produced.
The oil yield from peanuts depends on the pressing method and moisture content. Hot screw press yield: 42–53% by weight on peanut kernels (after dehulling). Cold press yield: 38–42%. Optimum pressing moisture is 8–10%. Every 5°C deviation from the optimal conditioning temperature (105–110°C for hot press) changes yield by approximately 1–2%. Whole-peanut pressing (with shell) yields 30–35% — significantly less than dehulled kernels. Peanut variety also affects oil content: Virginia types (large kernel) typically 42–47%; runner types 45–50%; Spanish types 50–55%.
Hot-pressed peanut oil (120–130°C barrel temperature, with 160–180°C pre-roasting) has higher yield (42–53%), deep amber colour, strong roasted aroma, and is the standard product in West Africa and East Asian cooking. Cold-pressed peanut oil (<50°C throughout) has lower yield (38–42%), light golden colour, mild natural flavour, and retains more natural antioxidants (tocopherols, phytosterols). Cold-pressed commands 2–3× price premium in organic/premium markets. The key trade-off is yield versus price: at 20 TPD, the 8–10% yield gap means cold press produces approximately 1.5–2 tonnes less oil per day — this revenue loss must be covered by the premium price.
Aflatoxin control requires Critical Control Points (CCPs) at multiple stages: (1) Reject mouldy, shrivelled, or discoloured peanuts at intake — use ELISA rapid test kits for screening; (2) Maintain storage moisture ≤9% and relative humidity <70% — measure with calibrated moisture meter and hygrometer; (3) Implement bleaching step in the refinery — activated earth reduces aflatoxin B1 by 40–70% per pass; (4) Test every production batch before dispatch using HPLC or ELISA methods. For EU export, aflatoxin B1 must be ≤2 μg/kg — this requires both strict raw material sourcing AND refinery bleaching. Neither measure alone is sufficient for consistent EU compliance.
A 10 TPD peanut oil plant requires: vibrating cleaning screen (TQLZ60), peanut dehulling machine (BTM-600), optional rotary roaster (CYJ-1.5), 2× 6YL-160 screw presses, crude oil settling tank (3T, carbon steel), plate filter press (BASY-320), and finished oil storage tanks (5T each ×2). With optional batch refinery (DG-1500 degumming vessel, neutralizing vessel, BL-1500 bleaching vessel, DZ-1500 deodorizing vessel with vacuum pump), the plant can produce food-grade refined peanut oil for mainstream retail markets. Total plant footprint: approximately 400–600 m². Installed electrical power: 35–45 kW (without refinery) or 55–65 kW (with refinery).
Peanut press cake from hot-press mechanical extraction contains 45–55% crude protein (dry basis) and 6–10% residual oil — a premium animal feed ingredient highly valued by poultry and swine producers for its high digestible protein content and palatability. In sub-Saharan Africa, peanut cake sells at $200–350/tonne depending on protein content, moisture, and location. A 20 TPD peanut oil plant produces approximately 11–12 tonnes of press cake per day. At $250/tonne average, this generates $2,750–3,000/day in cake revenue, offsetting 20–30% of total plant operating costs. Accurate protein content testing (Kjeldahl or NIR) allows premium pricing against commodity meal.
Our engineers have designed 50+ peanut oil plants from 5 to 200 TPD. Send us your capacity, raw material source, and target market — we will send you a free process configuration and equipment list within 24 hours.