Walnut prep: kernel grading + shell <2% + moisture 4-6% before ≤40°C press

Grading specification

Pre-press kernel quality control

• Visual + UV sorting at intake: reject rancid, darkened, or insect-damaged kernels (these contribute disproportionate FFA and peroxide).
• Size grading: USDA Light Halves (large), Light Pieces (medium), Light Amber (smaller, slight color). Mix size grades reduce press loading uniformity by 15-25%.
• Moisture conditioning: 4-6% target. Hot-air drying (≤40°C dry-bulb to avoid oxidation) if kernels arrive at >8% moisture.
• Lot traceability: harvest date, source, storage history. Premium walnut brands document lot per oil bottle; supports retail premium pricing.
• Shelling residue: <2% by visual + air-aspirator. Above 2%, oil color darkens and press partitions chip during 60-90 min cycle.

Handling spec

Why walnut prep differs from peanut or sesame

Project boundary

What to confirm before scoping Walnut Kernel Prep | Oil 60-70%, Shell <2%, Moisture 4-6%, ≤40°C Cold Press

Walnut Kernel Prep | Oil 60-70%, Shell <2%, Moisture 4-6%, ≤40°C Cold Press should not be quoted from an equipment name alone. Check feed lots, target oil, post-press handling, and packing rhythm in one scope before deciding which Walnut Oil Press modules stay. Factory cold-press page lists this oilseed — prioritize 355–500 (370–630 ton), pure press ~2 h/barrel.

When feed condition, moisture, impurities, batch weight, and product position are unclear, press tonnage and filter area become guesswork. Factory systems share 60 MPa and 2.2 kW motors; hot pure press is 30–40 min/barrel and cold pure press is ~2 h/barrel — cycle time matters more than brochure tonnage.

• Confirm whether feed is whole seed, kernels, pretreated material, or an existing semi-finished stream.
• Confirm whether the target is crude oil, filtered oil, bottled oil, drum ingredient oil, or a refining handoff.
• Hot cycle reference: pure press 30-40 min/barrel, ~1.5 h for 2 barrels with loading; cold pure press ~2 h/barrel, ~4.5 h for 2 barrels.
• Confirm batch rhythm, labor, changeover, retained samples, power (often 380V/50Hz/3ph), and site install conditions.

Factory model check

Match hot / cold models to factory hard data

Pin models to published factory specs before tonnage talk.

Hot 300/325: 300–325 ton, 60 MPa system, standard barrel Ø390×800 mm / max 100 kg, pure press 30–40 min/barrel, ~1.5 h for 2 barrels with loading, 2.2 kW motor. Cold 355/400/426/480/500: 370–630 ton, integrated frame, same 100 kg standard barrel, pure press ~2 h/barrel, ~4.5 h for 2 barrels with loading; optional Ø300 high-pressure barrel max 60 kg. Residual oil target ~≤5% (peanut hot often 6–8% measured).

• Standard barrel Ø390×800 mm, max ~100 kg crushed feed; optional Ø300 high-pressure barrel max ~60 kg.
• Cylinder material 27SiMn; cold frames are integrated molded steel; hot frames are typically H-type channel steel.
• Factory cold-press page lists this oilseed — prioritize 355–500 (370–630 ton), pure press ~2 h/barrel.

Equipment check

project scope needs to land in equipment interfaces

Once the route is clear, write the interfaces: how preparation feeds the press, how oil leaves the press, how filtration connects to tanks, and how packing receives finished oil.