Diced onion is the quiet workhorse of frozen vegetables — soups, sauces, ready meals, and foodservice kitchens buy it by the ton without thinking twice. That is exactly why it causes quiet problems: the wrong cut size disappears in a sauce or dominates a filling, and a specification that just says “diced onion” leaves every important decision to whoever is packing that day. Cut size is the specification. Everything else follows from it.
Cut size decides the application
The trade cuts IQF onion in a small set of standard dice. Each one has a natural application — match the dice to yours before quoting:
| Dice | Typical use | What goes wrong with the wrong size |
|---|---|---|
| Fine dice (~6 mm) | Sauces, dressings, processed fillings | Too small for visible-piece applications — vanishes |
| Standard dice (~10 mm) | Soups, ready meals, general foodservice | The safe default; confirm it is actually what you need |
| Large dice (~20 mm) | Kebabs, stir-fry mixes, visible-piece lines | Too large for sauces — uneven cooking, raw centers |
| Sliced / strips | Fajita mixes, toppings | Different product stream — do not substitute for dice |
The millimeter values above are trade-typical, not universal — confirm the exact cut definition with your supplier, because one factory’s “10 mm” is another’s “3/8 inch nominal.” State the dice as a number, and state the tolerance: dice uniformity (share of undersize fines and oversize pieces) matters as much as the nominal size.
Yield: why buyers switch from fresh
The commercial case for IQF diced onion is yield and labor, not flavor. Fresh onion loses roughly a quarter of its weight to peel and trim before it even reaches the knife, then more to cutting labor and waste. IQF dice arrives 100% usable, pre-cut, with no peeling line and no tears in the prep room. When you compare quotes, compare usable kilograms against usable kilograms — fresh weight against frozen weight flatters the fresh price.
The two quality risks to specify against
Dehydration (freezer burn). Dice have enormous surface area, which makes them the fastest product in the freezer to show dehydration if the cold chain breaks. White, dry patches on the dice surface are the visible sign. Specify continuous -18°C or below through the whole chain, and check a thawed portion for surface dryness on arrival.
Fines and clumping. Poor dice uniformity leaves a tail of fines that burn in the pan and turn to mush in sauce; temperature abuse during transit fuses dice into clumps. Both are checkable in a weighed sample — specify tolerances for each.
What to record during a product trial
- Dice uniformity: sieve or weigh-sort a portion — share of fines and oversize pieces against the quoted tolerance.
- Dehydration check: thaw a portion and look for white, dry surface patches.
- Clumping: whether the dice flow freely from frozen — fused blocks signal temperature abuse.
- Cook test: cook the dice exactly as your line does and check texture and flavor against fresh-cut reference.
- Yield math: usable kilograms per carton against your fresh-onion baseline.
Information to include in your RFQ
- Product name and freezing method: IQF diced onion
- Cut size as a number (mm) plus uniformity tolerance
- Onion variety or color if your application requires it (white/yellow/red behave differently)
- Packing: bulk carton weight
- Quantity, destination market, and target delivery time
- Cold-chain requirement: -18°C or below, stated in the contract
- Whether you need a pre-shipment sample from the offered lot
Name the dice size in millimeters and the tolerance beside it — that one line eliminates most diced-onion disputes before they start.
For the full product specifications behind this guide, see our IQF onion page. For the dried alternative, compare dehydrated onion; for fresh-cut supply without freezing, see fresh peeled onion.
