Contracts specify a maximum pulse moisture rather than a target, and the practical shipping window sits just below that maximum. Vorezan does not restate contractual limits as universal numbers — they differ by crop, by destination and by contract form — but the logic behind the window is consistent across all pulses.
The upper bound: biological stability
Moisture in a stored seed is only meaningful through water activity, the fraction of that water available to microorganisms. Above a certain water activity, storage moulds begin to grow; higher still and mycotoxin-producing species become active. Seed respiration also accelerates with moisture, and respiration generates heat and more water, which is how a marginally wet bulk goes from acceptable to spoiled inside a sealed container.
A container crossing the Black Sea and the Mediterranean in summer runs through a large diurnal temperature swing. Warm, moist air inside the box condenses on the cold steel roof at night and rains back onto the top of the cargo. This is container sweat, and it is the single most common cause of arrival claims on ambient pulse shipments. The drier the cargo loads, the less water there is in the system to condense.
The lower bound: mechanical damage
Over-drying is not free. A seed dried well below its equilibrium moisture becomes brittle. Handling through elevators, conveyors and the ship loader then generates splits, chips and coat cracks — precisely the defects that colour sorting was run to remove. Large-seeded crops with thin coats, such as kidney beans and large kabuli chickpeas, are the most vulnerable. Over-drying also destroys weight: mass sold is mass shipped, and every point of moisture removed below the contractual maximum is product given away.
How the window is managed in practice
- Measure by reference method. Oven-drying to a defined ISO procedure is the referee method; portable meters are used for line control and calibrated against it.
- Sample properly. Moisture varies by position in the bulk. Composite samples drawn across the load are the only meaningful basis.
- Let the lot equilibrate. Freshly dried seed has a dry surface and a wetter core; a reading taken straight off the drier is optimistic. Tempering for a day or more gives a true figure.
- Load cool. Cargo loaded warm drives condensation regardless of moisture. Aim to load close to ambient.
- Use container liners and desiccant. Kraft or ventilated liners plus desiccant poles absorb the water that does migrate, and cost far less than a rejected container.
What to write into the contract
State the maximum moisture, the reference analytical method, the sampling plan, the point at which moisture is determined (loading or discharge) and whether a moisture allowance or weight adjustment applies. Ambiguity on the determination point is the usual source of disputes, since a cargo can gain or lose moisture in transit. The cleaning, sorting and grading guide covers drying and tempering, and how long dried pulses keep covers what happens after arrival.