Canned foods are usually checked for container integrity, commercial sterility and product quality before export. That means can seam examination, vacuum and headspace checks, incubation tests, pH and Brix, and microbiological, chemical and sensory tests.
Some checks are done by the factory on every shift. Others are done by an outside lab on samples from each lot. Agree which ones you need in the contract, and who pays for each test.
Container integrity checks
- Double seam examination: the seam is measured and often torn down to check overlap, tightness and other dimensions against the can maker's specification.
- Vacuum: a vacuum gauge or tap test confirms the can holds a vacuum after cooling.
- Headspace: the gap between product and lid, which affects vacuum and heat penetration.
- Visual inspection: dents, rust, leaks, swelling and damaged lacquer.
- Coding: each can carries a legible batch and date code.
Commercial sterility
The key safety test is incubation. Sample cans from each lot are held warm for a set period, then checked for swelling, loss of vacuum and changes in pH or appearance. Some cans are opened and tested for surviving microbes. Temperatures and times vary by product and method, so ask the lab to state them.
Also ask to see the factory's thermal process records for your lots. These show the time and temperature each batch received. Under-processing is a common cause of spoilage, as explained in what causes swelling in canned mango pulp.
Product quality and safety tests
- pH and acidity, which decide how the product must be processed and how it is regulated.
- Brix, for fruit pulps and syrups. See what Brix level mango pulp should have.
- Colour, consistency, flavour and freedom from black specks or fibres.
- Yeast, mould and other microbes, depending on the product.
- Metals such as tin and lead, which can rise if cans are poorly lacquered or stored too long.
- Pesticide residues and contaminants, against the limits in your market.
- Additives and colours, if the product claims to be free of them.
Sampling matters
Results only describe the cans tested. Ask for samples drawn at random across the lot, not picked from the top of a pallet. Keep retained samples from each lot so you can test again if a claim arises. For a first order, consider testing more cans than usual, then reduce the number once results are steady. Ask the factory for its own shift records as well, so you can compare its figures with the lab's.
Where we come in
We review seam and process records at the cannery and draw random samples from your lots for testing at NABL-accredited labs. Our inspectors check cans, codes and cartons before loading. Start with a free sourcing review.