Nut dehulling is the mechanical removal of the outer green husk or hull from nuts such as walnuts and almonds shortly after harvest, preventing hull staining, mould migration into the shell and aflatoxin risk.
In trade practice
Dehulling machines use rubber rollers or paddles to split and strip the hull without damaging the shell; prompt processing within hours of harvest is standard practice for walnuts to avoid hull tannins staining the shell dark. Stained shells are downgraded or rejected by buyers requiring light-coloured in-shell product. Removed hulls are a by-product with uses in animal feed or biomass, and their disposal or sale should be noted in the processing record. Suppliers exporting to the EU should document dehulling date as part of the lot traceability file.
In a specification
A specification for in-shell nuts may include a maximum permitted hull residue percentage and a shell colour standard, with dehulling date recorded in the accompanying traceability document.