Spray drying sprays a liquid vegetable juice or diluted puree into a chamber of hot air, where the droplets dry almost at once into a fine powder. Drum drying spreads a thick puree on heated rotating drums, scrapes off the dried sheet and mills it.
Spray-dried powders are usually finer, lighter in colour and freer flowing, but often contain a carrier. Drum-dried powders tend to be coarser and darker, with a more cooked flavour, and are more often 100 percent vegetable.
How spray drying works
The vegetable is turned into a liquid feed. A nozzle or spinning disc breaks it into fine droplets inside a tall chamber of hot air. Water leaves the droplets in seconds and the powder is collected at the bottom or in a cyclone.
Juices high in sugar, such as tomato or beetroot, tend to stick to the chamber walls. Producers add a carrier such as maltodextrin to raise the drying temperature at which the powder stays free flowing. Our article on added carriers explains what this means for your label.
How drum drying works
A thick puree or mash is fed onto one or two large steam-heated drums. It forms a thin film that dries as the drum turns. A blade scrapes off the dry film as flakes, which are then milled to powder or sold as flakes.
The product spends longer in contact with a hot surface. That can darken colour and develop cooked notes. It suits starchy products such as potato flakes, and purees that dry well without help.
Side by side
- Particle: spray-dried is a fine, round powder. Drum-dried is flaky before milling and more irregular after.
- Flow: spray-dried usually flows more freely. Drum-dried can be dustier or lumpier.
- Colour: spray-dried often looks brighter. Drum-dried is often darker.
- Flavour: spray-dried keeps more fresh notes. Drum-dried tastes more cooked.
- Carrier: common in spray-dried, less common in drum-dried.
- Solubility: spray-dried powders usually disperse more easily in water.
- Typical uses: spray-dried for drinks, instant mixes and coatings. Drum-dried for soups, bakery, snacks and potato products.
Air-dried and milled: the third route
Many Indian vegetable powders are neither spray nor drum dried. Onion, garlic, carrot and spinach powders are usually made by drying pieces in hot air belt dryers and then milling them. These powders keep the fibre of the whole vegetable and are normally 100 percent vegetable.
So when a supplier says "vegetable powder", ask the method. A spray-dried tomato powder and an air-dried, milled tomato powder are different products. Our article on how tomato powder is made shows the range for one product.
Choosing the right one
Start from your use. If the powder must dissolve in a drink or coat a snack evenly, spray-dried may suit better. If you want a clean label with no carrier and can accept a coarser, more cooked product, drum-dried or air-dried may be the better choice. Order samples of each and test them in your actual recipe.
How we help
We confirm which drying equipment a supplier really runs, collect production samples by method, and have them tested at an NABL-accredited lab. To compare powders on a fair basis, start with a free sourcing review.