Walnut kernel is traded on colour and on size. Colour grades run from the palest, which command the highest price and go into visible confectionery and bakery use, down to the darker grades that go into fillings, pastes and industrial applications where appearance does not matter. Size runs from halves through quarters to pieces. Behind both of those sits the real risk in this product, which is not appearance at all: walnut is high in polyunsaturated oil and it goes rancid, and like all tree nuts it carries an aflatoxin risk that the European rules take seriously. A buyer who specifies only colour and size has specified the easy half of the problem.
Seasonality and availability
The Ukrainian walnut harvest runs from September into November. Kernels are dried, cracked and graded after harvest and supplied from store through the year. Freshness matters more than for most products in this range: an old kernel is not a cheaper kernel, it is a kernel that is closer to tasting rancid. Ask for the crop year and the production date, and buy accordingly.
What the buyer checks at intake
- Colour grade against a physical or photographic reference standard.
- Size grade and the proportion of halves, quarters and pieces.
- Moisture content, which drives both mould risk and texture.
- Peroxide value or another rancidity indicator if your specification sets one.
- Shell fragments and foreign matter, which is the physical hazard in this product.
- Aflatoxin certificate for the lot, against the limits in Regulation (EC) No 1881/2006.
- Smell. A rancid note is detectable long before a laboratory number looks alarming.
Related standards and routes
Ambient dry goods by road or container. Chilled transport is worth considering for long transits in summer. Suppliers should be able to produce aflatoxin results per lot and a BRCGS or IFS Food certificate for the packing site.