Surface Mould in a 500 kg Ketchup Batch
An FPO-registered tomato ketchup unit in Hooghly produces 500 kg batches. The recipe is tomato pulp 60%, sugar 28%, salt 2%, acetic acid 1.2%, onion, garlic, spices and a permitted preservative. The batch record shows total soluble solids 28°Brix and pH 4.6. The sauce is hot-filled at 88°C into 200 g glass bottles, capped immediately, cooled in a water bath and stored at ambient temperature. Tomatoes were held for seven hours in the yard on a hot day before pulping, and the pulp was not screened for rot. After 12 days, 5% of bottles show surface mould colonies; the mould count is 40 CFU/g and pH is 4.55. The owner argues that 28°Brix is high enough to preserve the product and that the mould must have come from the bottle caps. He wants to filter the affected bottles, reheat the sauce to 85°C, refill and sell them.
1. Assess the product as an acidified food. Is 28°Brix enough to prevent the surface mould, and what does the pH of 4.55 tell you?
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No, 28°Brix is not enough to prevent surface mould. Sugar lowers water activity only modestly at this concentration; it does not stop mould growth at the surface where oxygen is present. The pH of 4.55 is above the usual 4.2–4.3 safety margin for hot-fill acid foods and close to 4.6, where anaerobic pathogens become a concern. A hot fill at 88°C may not destroy heat-resistant mould spores, especially in a viscous sauce where the centre of the bottle heats slowly. Mould at the surface suggests either surviving spores or contamination from caps or headspace. The low mould count and 5% incidence fit under-processing or post-process leakage rather than a single spoiled bottle. The pH and TSS combination is therefore not a commercial sterility claim.
2. Decide what to do with the 12-day-old batch and write a corrected process specification for the next batch with at least three control points.
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Disposition: do not filter, reheat and sell. Mould growth may produce mycotoxins, and reheating would still leave a non-compliant, potentially unsafe product; condemn or dispose of it under FSSAI waste rules. Corrected specification: sort tomatoes and reject rotten fruit; reduce yard holding to under 4 hours; adjust pH to ≤4.2 with acetic acid; formulate to ≥28°Brix; hot-fill at ≥90°C with a verified holding time, or use a proper pasteurisation step; sanitise caps and maintain headspace; check seal integrity. Control points: pH of each batch, fill temperature, cap torque/seal, and a 48-hour incubation check. Release only after negative mould/yeast results and a label check.