White film and bulging jars in a 300 kg mango pickle batch
Meera's pickle unit in Jaipur makes mango pickle in 300 kg batches every June. To cut costs and suit customers who want less salt, she reduced salt from 18% to 10% of the mango weight, replaced the traditional 2 cm layer of mustard oil with a thin film, and topped up the jars with bare hands. Filled jars were kept near a south-facing window where the temperature reached 40–42 °C. After 25 days, four of ten jars showed a wrinkled white surface film, gas bubbles and a fruity-sour off-odour; two jars had bulged. The pH of a spoiled jar is 4.3, against 3.6 at filling. Meera proposes to scrape off the white layer, add hot mustard oil, relabel the jars and sell them at the local haat at a 30% discount before the festival season. She has no laboratory report and no record of the batch's salt content or moisture.
1. Identify the most likely group of spoilage organisms and explain, using the specific changes Meera made, why the batch spoiled. What information would you need before you could be certain?
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Most likely agents: osmotolerant yeasts such as Zygosaccharomyces, Debaryomyces and Candida, growing as a surface film; heterofermentative lactic acid bacteria may also be contributing gas.
Why the changes allowed it:
- Salt cut from 18% to 10% raises water activity from roughly 0.85 to about 0.92–0.93, removing the osmotic hurdle that was suppressing yeasts.
- The 2 cm oil layer was an oxygen barrier; a thin film lets strictly aerobic surface yeasts grow.
- Bare hands and wet jars are a direct inoculation route - pickle is not cooked after filling, so nothing later kills contaminants.
- Storage at 40–42 °C is close to the optimum for yeast growth, so 25 days is ample time.
- Bulging indicates CO₂; the pH rise from 3.6 to 4.3 fits yeasts and moulds consuming lactic and acetic acid, which weakens the acid hurdle further.
To be certain you need yeast and mould counts, total and lactic acid bacteria counts, pH, salt % and water activity, plus microscopy of the film. The pattern is typical of yeasts, but gas-forming Bacillus or clostridia cannot be excluded without a laboratory report.
2. Should Meera sell the batch after skimming and re-oiling? Give your decision with technical and regulatory reasoning, and state what must be done with the 300 kg.
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Decision: no. The batch must not be sold in any form, discounted or otherwise.
Technical reasoning: visible surface growth means counts far beyond acceptable limits, and metabolites, enzymes and any mycotoxins produced by moulds diffuse into the oil and pulp - they are not removed by scraping the surface. Many mycotoxins are heat-stable, so adding hot oil achieves nothing. Yeast and mould growth also raises pH, lowering the product's own protection. The result is at best spoiled food and at worst unsafe food; a discount price does not change that.
Regulatory reasoning: under the Food Safety and Standards Act, 2006, a food business operator (Section 26) is responsible for the safety of what is sold, and 'unsafe food' under Section 3(1)(zz) includes food that is spoiled, contaminated or unfit for human consumption. Selling it would expose Meera to seizure, penalty and cancellation of her licence, and to civil liability if anyone falls ill.
What to do: segregate the jars, mark them 'NOT FOR SALE - REJECTED', denature or destroy them under record, keep photographs, batch details and a rejection note, and trace and recall any jars already given to the haat. Then investigate the batch records before restarting.
3. Prepare a control plan so that next season's 300 kg batch can be sold with a 12-month shelf life.
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Formulation (product hurdles): restore salt to 15–18% of mango weight; dry the cut mango pieces in sun or a dryer to remove surface moisture before mixing; standardise acidity so the equilibrium pH is below 4.0 (food-grade acetic acid if needed); use only preservatives permitted for pickles at the permitted level; maintain a 2 cm mustard oil layer.
Process and hygiene: wash and dry jars, sterilise with hot water, use dry spoons and gloved hands, never bare hands; fill without headspace air pockets; avoid metal contact. Store below 30 °C, away from sunlight, not near windows.
Measurement and records: record salt %, pH, moisture/water activity and fill weight for every batch; keep a retained sample. Do a storage trial (room temperature plus an accelerated sample at 37–40 °C) testing pH, yeast and mould count and sensory quality at 0, 1, 3, 6 and 12 months before printing a 12-month best-before date.
People and compliance: train workers in GHP, keep medical fitness records, maintain the FSSAI licence, and label with batch number, date of manufacture, best-before and storage instructions.