Thermal Preservation. D 9.01 -- Thermal Preservation Definition Adding or removing heat to alter...

Thermal Preservation

D 9.01 -- Thermal Preservation

Definition Adding or removing heat to alter

shelf-life. Shelf-life -- time food can be stored and still maintain its quality Heat processing -- adding heat to a

food to destroy enzymes and some spoilage and pathogenic bacteria.

Cold processing -- removing heat from food to slow deterioration from enzymes and bacteria.


Types of Thermal Preservation Heat processing

Blanching Commercial sterilization Pasteurization Sterilization Dehydration Canning

Cold processing Refrigeration Freezing


Blanching Immersing food in

boiling water or steam to destroy enzymes.

Often used before freezing or drying foods.

Product shelf-life is short.


Commercial Sterilization Combines heat and

vacuum seal to destroy spoilage and pathogenic microorganisms.

Product shelf-life is long. Examples include water

bath, retort, or hydrostatic cooker and cooler


Pasteurization A low heat treatment

that destroys pathogenic microorganisms and stops enzyme activity

Products have a medium shelf-life.

Examples include batch, high temperature, and short-time.


Sterilization A high

temperature heat treatment that destroys all microorganisms.

Products have a long shelf-life.

Examples include aseptic canning.


Dehydration Low temperature heat

treatment that involves the removal of water as a means to prevent microbial growth.

Products have a long shelf-life.

Examples include tray, belt, drum, spray, vacuum, freeze-drying, sun, and oven drying


Concentration Removal of a portion of

water from food to prevent microbial growth.

Products have a medium shelf-life.

Examples -- open kettle, heat evaporation, vacuum evaporation, and filtration


Refrigeration

Slows enzyme activity and microbial growth.

Products have a short shelf-life.


Freezing

Slows enzyme activity and microbial growth

Products have a long shelf-life

Non-Thermal Preservation


Definition Involves manipulating the

properties of food or its environment without using heat.

Examples include: Irradiation Ohmic heating Ozonation High pressure processing


Irradiation

Exposure of food to ionizing radiation for preservation

In the U.S. irradiated foods are required to be labeled.


Ohmic Heating

Food is subjected to an alternating current flow between two electrodes.


Ozonation Water treatment

process used to destroy microorganisms by ozone, a gas produced by exposure of oxygen molecules to high electric voltage


High Pressure Processing

Preservation method where liquid and solid foods are subjected to pressures of 45,000 pounds per square inch or higher.


Tamper-evident Devices


Definition A package that has “one or more indicators or

barriers to entry which, if breached or missing, can reasonably be expected to provide visible evidence that tampering has occurred.”

Packages are made so they cannot be duplicated with commonly available materials or through commonly available processes.


Other considerations The visual indication should be

accompanied by a precautionary label. describing the tamper-evident feature(s)

and warning that absence of or damage to such

feature(s) at time of purchase is a sign of possible tampering.


Many different types There are many types of tamper-

evident devices. Research and development is on-

going to make these devices more secure.

Examples will be shown.


Food Packaging


What is food packaging?

Enclosing food to protect food from tampering or contamination from physical, chemical, or biological sources.


Six Functions of Packaging

1. Barrier between food and contaminants.2. Protects food from impact during shipping

and storage.3. Acts as a dispenser4. Protects food from moisture, gas, odors,

and light5. Identifies the contents6. Serves as a cooking and storage container.


Food Packaging Materials Metals (steel, tin, and aluminum) -- canned

foods Glass -- beverages, pickles, condiments Paper (usually coated with wax, plastics, or

aluminum foil) -- cartons of milk, crackers Plastics -- milk jugs, beverages, deli salads Packaging films (cellophane, edible films, and

coatings) -- candy bars, hot dog casings, chips Laminates (layering materials into one product)

-- drink boxes

D-9.02 Food Packaging

Packaging TypesFood package Food

Aseptic packaging

Liquid whole eggs

Bags Potato chips

Boxes Box of cereal

Cans Can of soup

Cartons Carton of eggs

Flexible packaging

Bagged salad

Wrappers Used to cover a package.



Reduced oxygen packaging

Some packaging methods involve changing the environment that surrounds food to increase the shelf life.

Reduced oxygen packaging (ROP) provides an atmosphere that has little or no oxygen in the environment surround the food.

Three types of ROP are: Controlled atmosphere packaging Modified atmosphere packaging Vacuum packaging


Controlled Atmosphere Packaging

Controls the movement of gases inside the package.

Used with: fresh-cut salads.


Modified Atmosphere Packaging

Flush the food container with a gas, CO2 or N2., before the container is sealed

Use with: potato chips and

other snack foods fresh pasta


Vacuum Packaging Remove all air,

including oxygen, from inside the packaging environment.

Used with: Country ham slices, deli meats, bacon


Determination of what type of package to use

The type of packaging material used with a specific food product depends on: the function the package must perform the protection needed conditions of shipping and storage chemical composition of the food