Twelve Kilos of Tomatoes and a Failing Refrigerator
A wedding in the family leaves Sunita with 12 kg of ripe tomatoes and 4 kg of raw mangoes in the first week of June, when the day temperature is 40 °C. Her small refrigerator holds only 3 kg and the power is cut for six to eight hours daily. A wholesaler offers ₹4 per kg for the tomatoes, less than half the market rate. Sunita has 10 clean glass jars with lids, 2 kg of salt, 1 kg of sugar, mustard oil and the usual spices; she has no pressure canner and no dehydrator. Her neighbour suggests keeping everything in the fridge, another suggests sun-drying on the roof, and her mother-in-law wants pickles and chutney made the old way. Three weeks later, one jar of mango pickle shows a white layer on top and a slightly musty smell, while the tomatoes kept in a bowl are leaking and soft.
1. Assign a preservation method to each lot and justify each choice using preservation principles and her actual constraints.
Read the worked answer
Tomatoes (12 kg) - split the lot.
- Sauce/chutney in jars (about 6 kg): tomatoes are acidic (pH below 4.5), so adding sugar, salt and spices and boiling the pulp, then filling hot into sterilised jars and sealing, destroys spoilage organisms and excludes air. This suits her jars and needs no pressure canner.
- Sun-drying (about 4 kg): slicing and salting, then drying on a clean cloth or tray for 2–3 days at 40 °C removes moisture below the level moulds need. Salt speeds water loss and inhibits microbes. Store the dried slices in an airtight jar.
- Sell or share the rest immediately (2 kg): with no cold storage, the market rate of ₹4 per kg is better than a total loss.
Raw mangoes (4 kg) - pickle. The principle is preservation by salt, acid, sugar and an oil seal: salt draws out water and selects lactic fermentation, the natural acidity of mango plus added spices lowers pH, and a layer of mustard oil cuts off oxygen and excludes mould. Sun-curing the pieces with salt and turmeric for 2–3 days before jarring is essential.
Why not the fridge? Refrigeration only slows microbes; with six to eight hours of power cut daily, the temperature rises repeatedly and the food spoils anyway. Sun-drying, salting, sugaring and oil-sealing work without electricity.
2. The mango pickle grew a white layer on top after three weeks. How should Sunita decide whether to salvage or discard it?
Read the worked answer
She should judge by where the growth is and how the pickle smells and looks below the surface, not by appearance alone.
Salvageable:
- The white layer is thin, on the surface only, and the pickle below is firm, bright and smells of mustard and spice.
- This usually means the oil seal was too thin or moisture entered when the jar was opened with a wet spoon. Skim off the top layer with a clean dry spoon, discard it, top up with mustard oil heated and cooled, add a little salt, keep the jar in the sun for two days and thereafter use a dry spoon. Check again after a week.
Discard:
- Growth has spread below the surface, the pieces are soft and slimy, the brine is cloudy and gassy, or there is a musty or rancid smell. This points to mould penetrating the flesh or to yeast/bacterial spoilage; mycotoxins can diffuse into the liquid, so scraping the top is not safe. Throw the contents away and sterilise the jar before reuse.
The tomatoes in the bowl are a clear case for discarding: leaking, soft fruit at 40 °C is a sign of bacterial breakdown, and eating it risks food poisoning. The lesson for next time is a thicker oil layer, dry spoons, and smaller jars that are opened less often.
3. Sunita's neighbour says the refrigerator, not the method, is the real answer. Explain, in terms a neighbour would accept, why refrigeration is a delay and not a method, and how she should judge whether a preserved food is safe.
Read the worked answer
Refrigeration works by slowing the growth of bacteria, yeasts and moulds - it does not kill them, and it does nothing to the enzymes that cause softening and browning. Once the food comes back to room temperature, the surviving organisms multiply again. With power cuts of six to eight hours in June, the refrigerator spends much of the day above 10 °C, so it is not even reliably slowing spoilage. True preservation removes the conditions microbes need: moisture (drying), oxygen (oil seal, airtight jars), or acidity and sugar (pickling, jam), or kills them with heat plus a seal.
How to judge safety at home:
- Smell and texture - sour, musty or alcoholic odours; slime; gas bubbles; softened flesh.
- Surface - visible fuzz, coloured spots, a cloudy brine, or a raised lid.
- Seal - a jam or sauce jar whose lid does not stay depressed has lost its vacuum.
- Rule of thumb - when in doubt, throw it out; spoiled low-acid food can cause serious illness, and the cost of one jar is far less than the cost of a hospital visit.