Thirteen kilos of surplus in a house without a fridge
It is the third week of May in Bhagalpur. Power cuts run six to eight hours a day and the family has no refrigerator. A relative has sent 8 kg of ripe tomatoes and 5 kg of raw mangoes, and part of the stock will spoil within four days. Last year the family made mango pickle in a steel bowl, used 1 cup of salt for 2 kg of mango, tied a cloth over the jar and kept it near the window; by July a white and green furry layer had formed on top. The mother skimmed it off and the family kept eating the pickle. This year they have mustard oil, turmeric, red chilli powder, salt, sugar, clean glass jars with metal lids, a pressure cooker, strong sunlight and a covered verandah. The mother wants to bottle tomato ketchup for the year, make mango pickle, and sun-dry the rest. The daughter asks whether the old pickle is still safe.
1. Divide the 8 kg of tomatoes and 5 kg of mangoes between ketchup, pickle and drying so that losses are minimised, and justify each choice by the preservation principle it uses.
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Tomatoes (8 kg) - high moisture, soft, spoil fastest.
- 4 kg for ketchup: cooking drives off water, sugar and salt lower water activity, acid (lemon juice or vinegar) drops pH, and hot filling into sterilised bottles plus a sealed lid excludes air. Principles used: concentration, lowered water activity, acidification, heat sterilisation, exclusion of air.
- 3 kg sliced, salted and sun-dried on the verandah for three to four days into sun-dried tomato leather: the principle is dehydration - removing water stops microbial growth. Store in a covered jar with a layer of oil.
- 1 kg eaten fresh now, because ripe tomatoes will not wait.
Mangoes (5 kg) - firm, acidic, better suited to pickling.
- 3 kg pickle: salt at roughly 100–150 g per kg, turmeric, chilli, mustard oil, sun for three to four days, then a 1 cm oil layer on top. Principles: salt draws out water and selects against spoilage organisms, acid from the fruit, oil seals out air, sunlight and dry handling prevent mould.
- 1.5 kg cut, salted and sun-dried as dried mango pieces (khatta-meetha or plain) - dehydration.
- 0.5 kg used fresh.
Why not all three methods on both fruits: the choice follows the raw material's moisture, acidity and texture, and the fact that ketchup made without preservative must be refrigerated after opening - which this house cannot do, so bottle in small jars, use one at a time, and cook it down well.
2. Diagnose at least three specific mistakes in last year's pickle that allowed spoilage, and give the correction for each.
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Mistake 1: steel bowl. Salt, acid and spices attack ordinary steel; metal salts leach in, the surface corrodes, and off-flavours develop. Correction: use glass, ceramic or food-grade plastic, with a dry wooden or stainless spoon.
Mistake 2: 1 cup salt for 2 kg mango - far too little. One cup is roughly 250 g, i.e. about 125 g per kg, but the salt also has to survive the water drawn out of the fruit, and the family was likely generous in the estimate. Correction: weigh salt at 100–150 g per kg of fruit and do not reduce it 'to taste'.
Mistake 3: cloth tied over the jar near the window. A cloth admits mould spores, dust and insects, and does not stop moisture from moving in and out. A window in humid May–June is the worst place. Correction: glass jar with an airtight metal lid, kept in a dry dark cupboard, opened only with a dry spoon.
Mistake 4: no oil seal and probably no proper sun-drying. Surface exposure to air allows aerobic mould and film yeast. Correction: sun the salted fruit for three to four days until the pieces are limp, then cover the pickle with a layer of mustard oil.
Mistake 5: wet spoons and hands. One wet spoon introduces water and lowers the salt concentration. Correction: dry spoon every time.
3. Answer the daughter: is last year's pickle safe once the mould has been skimmed off? Explain your reasoning and say what the family should do with that jar.
Read the worked answer
No - skimming is not a remedy. What is visible on the surface is only the fruiting body of the mould. The thread-like hyphae grow down into the liquid and the fruit, and many moulds that grow in pickles and jams produce mycotoxins that are not destroyed by ordinary heating. The liquid also carries the enzymes and waste products of the mould. Removing the top layer removes the evidence, not the contamination.
Second reason to discard: the mistakes - too little salt, steel bowl, cloth cover - mean the pickle may also have supported bacteria, not just mould. Salt was the only barrier and it was inadequate, so the safety margin is unknown.
What the family should do:
- Throw the whole jar away - do not feed it to anyone, do not 'use it up in small amounts', and do not sell or give it away.
- Wash and sun-dry the jar before reuse; boiling water rinse if it will take it.
- Do not taste-test to decide: mycotoxins are not reliably detected by smell or taste.
General rule to state: surface mould on a hard, low-moisture food can sometimes be trimmed with a wide margin; in a soft, moist, high-water-activity food such as pickle, ketchup or chutney, mould means discard. The family's habit of skimming and continuing is the single most dangerous practice in the case.