1. Bacteria and Storage and preservation of food To remember the different types of harmful bacteria and the danger zone details? To understand what food preservation is. To learn about the effect of temperature on foods. To learn about the different methods of food preservation.

2. Question: What is the ‘danger zone’ and what happens to bacteria in this zone? 3 – 63C is the danger zone where bacteria multiply very quickly

3. How can bacteria be controlled? If pathogenic bacteria are given the right conditions (warmth, food, moisture and time) in which to grow and multiply, they cause food poisoning and in some cases, death. Some bacteria also produce toxins which are poisonous. The young, old, pregnant and sick are the most vulnerable. It is possible to prevent bacteria multiplying to large numbers by adopting good hygiene practices and understanding the conditions which help bacteria to grow.

4. How does time affect bacteria? In ideal conditions bacteria multiply very quickly – they divide into two by binary fission. This means that within just a few hours, one bacteria is able to increase in number to several thousands or millions. A cake has three bacteria on it at 9am. If the bacteria can multiply (divide in two) every twenty minutes and the cake is left out in a room until 1pm, how many bacteria could there be on it? 12, 288

5. How do food and moisture affect bacteria? Bacteria like foods which are moist and have a high protein content such as red meat, poultry, fish and dairy products. They are called high-risk foods as they are foods which bacteria are most likely to grow on. They must be stored in a fridge at below 5ºC. Dry foods such as gravy powder and custard powder can be stored at room temperature because bacteria will not grow on them. As soon as they are turned into gravy and custard by adding liquid, they must be stored in a fridge.

6. What is food preservation? Food preservation involves the use of particular methods to make food last longer. There are both short- and long-term methods of preservation. Preservation extends the shelf life of food by killing the bacteria or slowing down the growth of bacteria. How does chilling preserve food? Chilling is a short-term method of preservation. Raw ingredients and food products need to be chilled. Chilling preserves food by slowing down the growth of bacteria.

7. Where should we store certain foods in the fridge? Complete Fridge Task

8. Food products that are chilled are usually called cook-chill foods. They are prepared and cooked in the normal way before being blast chilled (rapidly chilled to below 5°C (usually 2 °C) within 1½ hours using a special chiller). The food is kept at a low temperature during transport, storage and display up to when it is cooked. What are cook-chill foods? Cook-chill foods can only be kept for a few days unless special packaging is used. The food must be cooked to above 70°C and eaten within two hours.

9. Freezing was first used as a method of preserving food in China in 1800BC. It is a long- term method of preservation. It preserves food by stopping the growth of bacteria. The bacteria remain dormant until the food is defrosted. Raw ingredients and food products can be frozen. Quick and controlled freezing is needed so that large ice crystals do not form and break the cell walls of the food. In modern methods of freezing, small crystals are formed meaning that the food is much more likely to retain its structure once it has been defrosted. How does freezing preserve food?

10. Freezing and Boiling Temperatures Fridge Thermometer Chilling 0 - 5C Freezing – minus 18C Work in pairs to answer questions about low temperature methods

11. 72 degrees – Temperature for reheated food for duration of 2 mins 63 degrees – Food should be heated above this temperature – bacteria beginning to die Above 121 degrees All bacteria and spores are destroyed Above 121 degrees All bacteria and spores are destroyed

12.  LEARNING OUTCOMES: HOW DID YOU GET ON? Do you remember the different types of harmful bacteria and the danger zone details? Do you understand what food preservation is? Do you know about the effect of temperature on foods. Can you name different methods of food preservation.

13. True Story - Hovis Bread Factory 2010 – yuck!