Chapter 19: Thermal Preservation: Hot and Cold Processing Flashcards Preview

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Flashcards in Chapter 19: Thermal Preservation: Hot and Cold Processing Deck (34)
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1

What is Thermal Preservation?

Thermal Preservation of food involves changing its temperature

2

What is Heat Processing?

Transfer heat energy into food and destroys enzymes and bacteria that cause spoilage

3

What is Cold Processing?

Pulls heat energy from food to slow molecular movement, thus slowing spoilage

4

What is the Goal of Food Preservation?

Goal of food preservation is o increase the shelf life of a food

5

Heat does what to enzymes?

Heat denatures enzymes and destroys microorganisms that lead to food spoilage and contamination

6

Cooking does what for Shelf Life?

Cooking Extends shelf life as long as the food is also packaged to prevent recontamination

7

What is Pasteurization?

is a low-heat treatment that destroys pathogenic microorganisms and stops enzyme activity

8

What are some examples of foods that are Pasteurized?

Beer, wine, fruit juice, milk, oysters and eggs are pasteurized
- Processing time and temperature depend on the microorganisms and enzymes in a food

9

What is Batch Pasteurization?

Batch Pasteurization is best with liquids; they are heated in a large vat with slow stirring, pumped over a cooling plate, then packaged and sealed

10

What is High Temperature-short time Pasteurization (HTST)?

it rapidly heats and cools liquids;liquids are pumped through heat exchangers, then cooling tubes, and immediately packaged and sealed

11

What happens to HTST milk?

It is forced between metal plates or through pipes heated on the outside by hot water and milk is heated to 72C (161F) for 15 seconds

12

Ultra high-temperature (UHT) sterilization means what?

Ultra high-temperature (UHT) sterilization holds the milk at a temperature of 140C for 4 seconds
- During UHT processing milk is sterilized and not pasteurized
- This process lets consumers store milk or juice for several months without refrigerations

13

What is Commercial Sterilization?

1. Is used for canned foods in sealed containers
2. Is a method used commercially as well as for foods canned at home
3. Destroys all microorganisms that cause illness, produce toxins, or result in spoilage

14

Sealed cans prevent what?

Sealed cans prevent recontamination and growth of any spores that may be present

15

What is Sterilization?

it destroys microorganisms completely, is accomplished by moist heat and is limited to pureed or liquid foods

16

For Sterilization what temperature should food be at?

All parts of all food must reach 121C for 15min

17

What does Aseptic mean?

Aseptic means free of pathogens

18

What is Aseptic Canning?

1. Involves sterilizing the food, placing it sterilized containers, and sealing the containers
2. Can be used for a wide range of container sizes and packaging materials

19

What are Retorts/

Retorts are large commercial pressure canners with special locks and valves

20

For the Retorts process what is monitored?

Temperature and pressure are monitored during the heating process

21

What are Still Retorts?

Since cans of food do not move in a still retort, food is more likely to burn, therefore temperature is limited

22

What are Agitating Retorts?

Agitating retorts gently shake cans during processing

23

Heat changes what?

Heat changes texture, flavour and nutritive value of foods
- Goal is to add heat energy to preserve a food product while maintaining as many original qualities as possible

24

What is Heat Transferred by Conduction?

Used when food does not move in the container, such as corned beef hash, pumpkin pie filling and tomato paste
- Size and shape of container are important considerations

25

What is Heat Transfer by Convection?

sets up currents in liquids that speed the transfer of heat energy; is used for liquids, purees and chunks of food suspended in liquid
- Time and temperature are based on the size of the food chunks

26

What is the Cold Point?

the last point in a can or mass of food reached the desired temperature

27

Where is the Cold Point located when being heated by conduction?

Located in the centre of the can when heating by conduction

28

Where is the Cold Point located when being heated by convection?

Located just below the centre of the can when heating by convection

29

What are some time versus temperature considerations?

Balance the destructive effects of heat on the pathogens against those on food products

30

What is the Thermal Death Curve?

is the line plotted on a graph showing the time needed to destroy pathogens at a given temperature
- The lower the temperature, the longer the cooking time needs to be