Swelling in canned mango pulp usually comes from one of four causes: the pulp was under-processed, the can leaked after processing, the fruit or pulp was already spoiling before canning, or the acidic pulp reacted with the tinplate and released hydrogen.
Treat any swollen can as unsafe. Do not taste it, and handle it with care. Keep it for investigation, along with normal cans from the same lot and the carton markings, so the lab and factory can trace the cause.
Microbial causes
- Under-processing: the heat treatment was too short or too cool for the can size and pulp consistency, so yeasts, moulds or bacteria survived.
- Post-process leakage: microbes entered through a faulty double seam or a damaged can, often from cooling water or rough handling while cans were hot.
- Pre-process spoilage: fruit or pulp fermented while waiting to be canned, so the product was spoiled before it was sealed.
- Heat-resistant moulds: some moulds found on fruit can survive normal processing if the raw fruit is dirty or poorly sorted.
Non-microbial causes
- Hydrogen swell: acid in the pulp attacks the tinplate, usually where lacquer is damaged or weak, and the gas bulges the can. Risk rises with time and warm storage.
- Overfilling or low vacuum: a can that is too full, or not properly exhausted, may bulge slightly without spoiling.
- Storage heat: high temperatures in warehouses or containers speed up both corrosion and microbial growth.
- Dents: damage to seams can open a path for leaks.
How to tell which cause it is
A lab can open affected and normal cans and check pH, gas, microbes and the seam. If microbes of one kind are found, under-processing is likely. A mix of microbes often points to leakage. Hydrogen with no microbes points to corrosion. Pair the lab findings with the factory's process and seam records for that lot. The general test set is in what tests are done on canned foods before export.
How to prevent it
- Buy from canneries with validated thermal processes and complete records for each lot.
- Check seam records and do your own seam checks on samples.
- Ask for incubation test results for each lot before shipment.
- Specify can type and lacquer suitable for acidic pulp.
- Store and ship in cool conditions, and use stock within its stated shelf life. See the shelf life of canned and aseptic mango pulp.
- Handle cartons gently, since dented seams can leak. Reject dented or rusty cans at inspection.
How we help
We audit mango pulp canneries in season, review process and seam records, and draw samples for incubation and lab testing before your lots ship. If cans swell after arrival, we help gather the evidence for a claim. Ask for a free sourcing review.