Interactive lesson

Safety and storage, step by step

Interactive lesson: the risks of food from fat, oil, honey and sugar, the signs of botulism, the cold chain, pressure-canned meat in jars and safe disposal.

Free sample Chapters 1 and 2 (8 steps) are free. The full lesson comes with the Safety and storage module. Already bought? Unlock

This lesson is general guidance, not professional training. Local regulations and expert advice always take precedence. Read our disclaimer.

The whole lesson as text

1. Risks by product

Fat, honey and thick syrup keep food well, but when it does go off, it goes off quietly.

Meat in lard — The main risks are botulism and Trichinella. It is kept safe by salt, cooking to 72 °C (poultry 74 °C) and a cold larder below 10 °C (50 °F).
Cheese in oil — The risks are listeria and botulism. It is kept safe by pasteurisation, salt and the fridge.
Walnuts in honey — The risks are rancidity and aflatoxin. Only dry nuts and honey with up to 18 % water, in a dark larder. Mouldy walnuts are thrown away.
Honey and babies — In babies, spores from honey can germinate in the gut. Honey and any product with honey aren't given to children under 12 months.

Why: Botulism changes neither smell nor taste, listeria grows in the fridge, and mould on nuts makes poisons that roasting doesn't destroy. So safety isn't checked with your nose and tongue, but with the method, a thermometer and a date.

Every recipe in the series has at least one more barrier: salt and cooking, acid, sugar or cold.
An opened jar from the larder goes into the fridge.

2. Botulism

A jar of food can be deadly while looking and smelling completely normal.

Conditions for the toxin — No air, pH above 4.6, enough water and warmth. A suspect jar isn't tasted, not a drop.
First signs — Usually within 12–36 hours: double vision, drooping eyelids, dry mouth, difficulty swallowing and speaking, weakness from the top down. No fever.
Ambulance at once — 999 or 112 in the UK and Ireland, 911 in the US and Canada. Take the leftover food and the jar, closed in a bag, and tell the doctor what was eaten and when.
Heat before eating — Heat food from fat and low-acid food from jars until piping hot all the way through, roughly 10 minutes from boiling. It is the last line of defence, not a replacement for a good method.

Why: A botulism spore germinates in food without air that isn't acidic, has enough water and stands in the warm. Fat, oil and a closed jar provide the conditions without air. The toxin is destroyed by heat, but the spores aren't.

Don't throw away or eat the rest of the same batch until you have asked the doctor or the environmental health service.
Find out who else ate the same food and tell them, even if they have no signs.