Reference
Frequently asked questions
31 questions people actually ask — the practical, the safety-critical and the ones that quietly decide whether a batch succeeds. Filter by topic or search the whole set.
Where a question touches food safety, the answer here is a summary. The full reasoning, thresholds and caveats are in the food safety chapter — read that before you apply anything to food you will sell or serve to others.
| Number | Applies to | Why it is the number |
|---|---|---|
| aw ≤ 0.60 | All dried food | Below it no mould, yeast or bacteria grows — the single target that replaces every moisture percentage |
| aw ≤ 0.86 | Intermediate products | Staphylococcus aureus is the highest-aw pathogen of concern, and it can leave toxin behind |
| 160ߙ°F / 71ߙ°C | Jerky and other meat | Internal temperature for lethality; 165ߙ°F / 74ߙ°C for poultry. Drying alone is not a kill step |
| MPR ≤ 0.75:1 | Jerky | The USDA moisture-to-protein ratio for a stable, room-temperature product |
| ≤ 5ߙ% moisture | Herbs, leafy greens | Bone dry and crumbly; anything more cakes, browns and moulds |
| 6–8ߙ% / 12–20ߙ% | Vegetables / fruit | Crisp against leathery — the practical feel tests that sit behind the numbers |
| 5–7 days | Conditioning | Sealed rest that lets moisture equalise through every piece before packaging |
| ≤ 20ߙ°C, ≤ 60ߙ% RH, dark | Storage | Cool, dry and dark slows oxidation and stops the food pulling water back out of the air |
| 48 hours at −18ߙ°C | Pest control for incoming goods | Freezing kills insect eggs and larvae without changing the product |
Questions and answers
Still stuck?
🩺 Troubleshooting guide
Mould, case hardening, stickiness, browning, rancidity, slow batches, pests — with causes and fixes.
🧮 Calculators
Yield, water activity, drying time, tray sizing, energy cost and solar sizing to check your own numbers.
📕 Glossary
Definitions for every term used here, from water activity to glass transition.
📚 Resources
Extension guides, textbooks, standards bodies and where to ask a human being.