Archive
Drying & Dehydration
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What is water activity and why does it matter more than moisture?
Water activity, written a-w, is the ratio of the vapour pressure of water in a product to the vapour pressure of pure…
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What is the difference between freeze-dried and dehydrated?
“Dehydrated” is normally used to mean dried with heat and airflow, most often in a hot air tunnel or cabinet. “Freeze-dried” means…
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What is rehydration ratio and how is it measured?
The rehydration ratio is the drained mass of a rehydrated sample divided by the dry mass used, measured under stated conditions. A…
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Are sulphites allowed in organic dried fruit?
The permitted uses of sulphur dioxide and sulphites in organic production are narrower than in conventional production. Organic processing may only use…
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Why is freeze-dried fruit so expensive?
Because the process is slow, energy-intensive and capital-intensive, and because the product cannot be shipped in cheap packaging. None of this makes…
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How long does dried fruit last?
There is no single answer, because shelf life is a property of a product **in a pack under conditions**, not of a…
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What moisture content should dried fruit have?
Target moisture content varies widely by commodity, by format and by intended use, so a single figure across dried fruit would be…
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Does freeze-drying preserve nutrients better than hot air drying?
Generally yes, and the reason is thermal load rather than anything specific to sublimation. Heat-sensitive and oxygen-sensitive nutrients degrade as a function…
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Freeze-Dried vs Air-Dried Fruit: What Actually Differs
A technical comparison of freeze-drying and air-drying for fruit: what each process does to the cell structure, how the two behave in…
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Water Activity and Shelf Life in Dried Products
What water activity measures, why it predicts microbial stability better than moisture content, how it behaves during storage and transport, and how…