Food Storage
Senior 3 · Home Science
Food Storage
Lesson 2 of 4
22 min
Let's begin
A restaurant kitchen has three different "climates" behind three doors. The store room is cool, dry and dark: sacks of beans and rice, tins of tomato paste, cooking oil and sugar. The fridge holds fresh milk, cheese, yoghurt and the evening's tilapia at a few degrees above freezing. The freezer, colder than any place on Earth where people live, holds a month's supply of minced meat. Put any food in the wrong room and it spoils: Irish potatoes turn green in the light, avocados blacken in the cold, and milk sours on a warm shelf in a day. This lesson explains the main types of storage and which foods belong in each.
Definition
Shelf life: how long a food stays safe and of good quality when stored correctly.
Perishable food: food that spoils within days, such as milk, meat, fish, cooked food, leafy vegetables and ripe fruit.
Semi-perishable food: food that keeps for weeks or a few months, such as Irish potatoes, onions, oranges and flour.
Non-perishable food: food that keeps for many months if dry and sealed, such as dried beans, rice, sugar and canned food.
Dry storage, refrigerated storage, frozen storage: storing food at room temperature in dry conditions, at 0–5 °C, and at −18 °C or colder.
You met the danger zone in Senior 2: bacteria multiply fast between 5 °C and 60 °C. Each type of storage keeps a food out of conditions in which it spoils, by cold, by heat, or by keeping it dry.
| Type | Conditions | Foods | Rules |
|---|---|---|---|
| Dry store (pantry, store room) | cool, dry, dark, well ventilated | flour, rice, dried beans, sugar, salt, pasta, canned food, oil, tea, coffee | shelves at least 15 cm off the floor and away from walls; sealed, labelled bins; no chemicals in the food store |
| Vegetable store | cool, dark, airy | Irish potatoes, sweet potatoes, onions, pumpkins | keep potatoes in the dark so they do not turn green; keep onions and potatoes apart; air them in baskets or nets, not plastic bags |
| Refrigerated storage | 0–5 °C | milk and milk products, raw and cooked meat, fish, cooked leftovers, cut fruit, salads | check the temperature daily; cover everything; do not overfill, so cold air can move |
| Frozen storage | −18 °C or colder | meat, fish, poultry, some vegetables, bread, prepared dishes | wrap tightly to stop freezer burn; label and date; keep the door shut |
| Hot holding | above 60 °C | cooked food waiting to be served | for service time only; never to "store" food for later |
Not every food likes the cold. Bananas, avocados, mangoes, tomatoes and pineapples are tropical fruits: below about 10 °C their skins blacken and their flavour suffers (chilling injury). Ripen them at room temperature and refrigerate only once ripe or cut. Fresh cassava roots are the opposite extreme: they begin to spoil within about 48 hours of harvest, so they are peeled and cooked, dried into chips or flour, or left in the ground until needed.
Worked example
Worked example 1: putting away a delivery. Where should each item go: (a) 50 kg of dry beans; (b) 20 litres of fresh milk; (c) 10 kg of frozen minced meat; (d) a bunch of green (unripe) bananas; (e) a sack of Irish potatoes; (f) a 5-litre container of cooking oil?
Worked example
Worked example 2: a power cut. A full chest freezer loses power at 18:00. US food safety guidance says a full freezer kept closed holds its temperature for about 48 hours, and a half-full one for about 24 hours. Until what time should the food stay safe?
Warning
Never store cleaning chemicals, paraffin or pesticides in the food store, and never put them in empty food or drink containers: people have been poisoned by drinking bleach or paraffin kept in a juice bottle. Keep them in their own labelled containers, in a separate locked cupboard.
Tip
Memory hook: "Minus 18, zero to 5, dry and cool, above 60." Four numbers for four kinds of storage: freezer, fridge, dry store, hot holding.
Practice
Sources and credits
