02 · Dried Fruit & Nut Processing — Equipment
Freezes food and removes the ice under vacuum by sublimation, producing crisp, light products such as freeze-dried fruit and vegetable snacks.
Short answer: A freeze dryer first freezes food and then removes the ice under vacuum, so the water turns directly into vapour without the product shrinking much. The batch load of fresh product, the target cycle time and the condenser ice capacity together decide the size of the machine, and the texture and rehydration you want decide the cycle.
Prepared product is spread on trays and frozen, either on the dryer shelves or in a separate freezer. The trays go into a vacuum chamber, and vacuum pumps lower the pressure. Gentle heat is supplied through the shelves, so the ice in the product sublimes into vapour. The vapour travels to a very cold condenser, where it freezes again; this is the main drying stage.
When most of the ice is gone, shelf temperature is raised for secondary drying to remove water still bound in the product. At the end the chamber is brought back to atmospheric pressure, often with dry air or nitrogen, and the product is packed quickly because it picks up moisture from the air. The condenser is then defrosted before the next batch.
| Form | Suits | Watch out for |
|---|---|---|
| Cabinet batch unit | Product development, small-scale premium lines | Throughput limited by single chamber cycles |
| Industrial tray system | Daily production of fruit and vegetable snacks | Needs freezing, tray handling and dry packing room |
Product is prepared by a fruit and vegetable washer and a vegetable cutting machine, and may be pre-frozen in a food freezer. After drying it goes to packing, often with a multihead weigher and moisture-barrier pouches. It is the drying option for crisp products in a dried fruit processing line; compare it with a hot-air dryer.
Cabinet batch unit
a single chamber with shelves; suits pilot production, product development and smaller batches.
Industrial tray system
larger chambers with trolleys and separate freezing; suits continuous daily production.
Our engineers check these points with you, so the quotation fits your site rather than a catalogue default.
Cycles are long compared with hot-air drying and depend on product thickness, water content, loading and shelf temperature. We estimate the cycle from your product and refine it during trials.
Refrigeration for freezing and the condenser, vacuum pumps and shelf heating all use energy over a long cycle. Loading density, cycle optimisation and local energy prices make the biggest difference.
Common methods are watching product and shelf temperatures converge, a pressure rise test when the chamber is isolated, and checking residual moisture of samples. We agree the method with you at commissioning.
Tell us your raw material, finished product and target output. Our engineers reply with a matched configuration and quotation.
What to send with your inquiry
Email sales@hnfoda.com
Compare hot-air, heat pump, freeze and microwave dryers for mango and tropical fruit: quality, energy, sizing and a quote checklist.
Dried Fruit & Nut Processing
Investors and food companies starting or expanding dried fruit, fruit chip or dried fruit snack production.
Sized to fresh fruit input (kg/h or tonnes per day); dried output depends on moisture removed
Dried Fruit & Nut Processing
Date packers and processors adding value with washed, pitted or paste products for retail and industry.
Sized to whole date input (kg/h or tonnes per day)
Dried Fruit & Nut Processing
Food companies and brand owners launching peanut butter, almond butter or nut spread products.
Sized to roasted nut input (kg/h); output is close to input for pure nut butter
Dried Fruit & Nut Processing
Snack nut producers making salted, spiced, honey-roasted or coated nuts.
Sized to roasted nut input (kg/h) plus the seasoning added
