Fruit powders cake on long ocean legs. Specify water activity, not just moisture
2026-10-05
Dehydrated vegetable products like onion flakes tolerate a long sea leg with little drama. Spray-dried fruit powders are less forgiving, and the reason is sugar.
Mango and ripe banana powders are rich in fructose and glucose. These sugars are strongly hygroscopic, meaning they actively pull moisture out of the surrounding air. They are also thermoplastic: above a certain temperature, which falls as moisture content rises, the amorphous sugar matrix softens and individual particles begin to fuse. The practical result is caking, from a few soft lumps through to a solid block that has to be broken and re-milled, with colour and flavour damage along the way.
A container crossing from Nhava Sheva to Rotterdam or Houston spends weeks in conditions nobody is monitoring. Deck stow in the tropics can take internal temperatures well above ambient. Humidity cycles as the vessel moves between climates. A powder that was perfectly free-flowing at the factory gate can arrive compacted, and the certificate of analysis showing an acceptable moisture at production will not explain why.
This is why water activity is the better parameter to specify. Moisture content tells you how much water is present by weight. Water activity tells you how available that water is to move, which is what actually governs caking, microbial growth and the glass transition behaviour of the sugar. Two powders at the same moisture percentage can behave quite differently if their water activity differs, and it is the second number that predicts what happens in the box.
What to agree before production: a maximum water activity as well as a maximum moisture, measured and reported on the lot certificate. The pack, because barrier properties matter more here than on flakes. Whether an anti-caking agent is acceptable in your formulation and under your label, since it is a legitimate solution but not one every buyer can use. And the storage conditions at the destination, because a correctly specified powder put into a humid warehouse will still cake.
Pack deserves a specific mention. A food-grade polyethylene liner inside a fibre drum or a multi-wall sack is the common arrangement, and the integrity of that liner is what stands between the powder and the atmosphere. Aluminium foil laminate gives a better barrier at higher cost. For high-value or long-storage material it is usually worth it.
None of this makes fruit powder a difficult product to import from India. It makes it a product where the specification conversation has to include two or three parameters that do not come up on dehydrated vegetables. A supplier who quotes you spray-dried mango powder on price and mesh alone has not had that conversation with you.
We are a new exporter and we would rather raise this at enquiry than have it discovered at discharge. Tell us the destination, the transit time and your storage conditions, and we will specify the pack and the water activity limit against them.