Check in two ways. Test samples drawn from across each lot at an accredited lab for salmonella, hygiene indicators, yeast and mould, and mycotoxins. Then check the plant itself, because a clean test on one sample does not prove the whole lot is clean.
Salmonella and mould problems usually start after processing, when cooled meal picks up contamination or moisture. The plant's handling after the toaster matters as much as the process.
Mould also tends to follow moisture. A lot that left the plant dry can still arrive mouldy if it was loaded warm or sat in a humid container for weeks, so check the voyage as well as the plant.
Where contamination comes from
- Recontamination after heat: meal leaves the desolventiser-toaster hot enough to kill most bacteria, then picks up salmonella from dust, birds, rodents or dirty conveyors.
- Condensation: warm meal in cool bins or containers creates wet spots.
- Wet storage: leaking roofs, damp floors and high moisture in the meal support mould.
- Old stock: meal held too long in humid weather.
- Dirty containers or bags.
Lab tests to order
Limits depend on your market and customer. Feed rules for salmonella differ by country, and many feed mills set their own limits. Check with your feed authority and customers.
- Salmonella: detection in a stated sample size, commonly 25 g, with a result of absent.
- Enterobacteriaceae: a hygiene indicator. High counts point to poor control even if salmonella is absent.
- Yeast and mould count: shows mould load and freshness.
- Aflatoxin and other mycotoxins: mould can produce toxins that remain after the mould dies.
- Moisture: the main condition for mould growth.
Sampling properly
Salmonella can be patchy. One small sample from the top bag can miss it. Take sub-samples from many bags across the lot, combine them as agreed, and seal and code them. Send one set to the lab and keep a counter-sample. See who should draw the sample for testing.
If salmonella is found, do not accept a retest of a fresh sample from the same lot as proof it is clean. Agree in advance what happens to a positive lot.
Options include rejection, treatment where your market allows it, or diversion to a use with looser limits. Write the choice into the contract so there is no argument later.
What to check at the plant
- Clean, covered cooling and conveying after the toaster.
- Bird and rodent control in meal storage.
- Dry, sound godowns with stock rotation.
- Meal cooled before bagging and loading.
- Regular in-house tests for salmonella and moisture, with records.
- Clean, dry containers. See how to prevent condensation and mould in oilseed containers.
How we help
During audits we look at what happens to meal after the toaster, from cooling and storage to pest control. Before loading we draw sealed samples for salmonella and mould tests at an NABL-accredited lab. Ask for a free sourcing review.