Keeping Food Fresh

Keeping Food Fresh

Food lasts longer when preservation changes conditions microbes need or slows chemical reactions. Common methods include _____, _____ and an _____. Because they work differently, safe combinations can offer more protection.

Here, refrigeration means keeping food cold, usually below 5°C, so most microbes multiply more slowly. It does not kill them, so chilled food still has a use-by date. By contrast, heat treatment means warming food to a set temperature for enough time to kill many harmful microbes. Pasteurising milk is an example.

After food has been prepared safely, an airtight seal means a closed barrier that stops air passing through an opening. The seal is the barrier around the opening, not the jar or tin: that container holds the food. Less oxygen can slow mould growth and some chemical changes.