Meat is putrefied due to the action of bacteria , moulds , yeasts.
To grow and proliferate the organisms temperature is necessary. Due to this classify the organisms,
1-Pschyrophiles: have optimum temperature range of -2 to 7*c.
2-Mesophiles: have 10 to 40*c.
3-Thermophiles: have 43 to 66*c .
Organisms also need water for growth.
Why Preserve Meat???
Delays product spoilage
Extends life of the product
Improves product quality
To preserve the meat temperature must be
1- : -2*c by chilling or freezing.
2- : 66*c by pasteurization , cooking or sterilization.
To preserve the meat , remove the water by dehydration , freezing , curing.
Types of Preservation Techniques
Types of Meat Preservation
Removal of water from meat.
Kills bacteria if temperatures reaches 160 degrees.
Slows the growth of bacteria
20 degrees below zero eliminates bacterial growth
Low pH retards bacterial growth
Types of Meat Preservation
6. Irradiation -
Low levels kill bacteria in fresh meat products
Packaging meat into sealed containers and heating meat to kill bacteria
Compounds make meats inhospitable to microbial growth.
Salting and Sugaring-
Prevents microbial growth
Forms antibacterial chemicals to the meats surface
Typical Methods of Food Preservation :
Pasteurization kills spoilage and pathogenic organisms (1864 – Pasteur)
Longer temperatures and times can sterilize foods
Refrigeration or freezing inhibits microbial growth
Typical Methods of Food Preservation :
Inhibitors of organism growth such as salt, sodium nitrite, and propionates
Removing bacteria from liquids by centrifugation
Optimum temperature (0 °F or lower)
Meat freeze at -1.4*C
Works by completely stopping enzyme activity & inhibiting spoilage microorganisms
REMEMBER: Thaw meat at refrigeration temps or in the microwave
DO NOT THAW AT ROOM TEMPS
How long with frozen meat last?
Beef – 12 months
Pork - 6 months
Lamb – 6-9
Poultry – 3-6 months
Disadvantages of freezing
Frozen meat stored too long become dry , less palatable and rancid.
After thawing it is less durable than fresh-killed or chilled meat.
When frozen meat is thawed it weeps or drips which consist mainly of water, salt, protein and demaged blood corpuscles.
Loss of weight due to drip in beef is up to 3% while in mutton , lamb or pork loss is less than beef.
Yellowish –brown or whitish areas seen on the surface of frozen meats.
It is due to excessive drying of the surface.
Phenomenon involves the formation of a
condensed layer of the muscular tissue just under the surface. this prevents moisture coming to the surface from the depth of the meat.
Chilling of meat
It is useful when meat is stored for short time up to 35 days.
It is kept at b/w -1.4*c and 1*c preferably in the dark as light has the effect of oxidizing fats.
Atmosphere keep dry to prevent the mould formation
5-10%CO2 helps to prevent the growth of mould and bacteria.
It is important that temperature does not reach -1.4*c otherwise meat is frozen..
Toughness develops in lamb carcasses, if they are exposed to low temperature within about 16 hours after slaughtering
pH is about 6.3 and ATP levels are high ,lowering of the temperature causes the muscle to contract. It starts normally at 15*c and become greater down to 0*c.
Beef carcass do not chilled quickly b/c of the thickness of the muscles.
Due to rapid fall in the pH there is no problem of cold shortening in the pig carcass.
Works by heating products to high temperatures to kill microorganisms
2 types of cooking
Products are cooked to 150-170 °F
Kills most (but not all) microorganisms
Product must be REFRIGERATED
Products cooked under pressure to 250 °F
All microorganisms killed
Products are shelf stable
Example: Canned Hams
- Meat, fish and some other foods may be both preserved and flavored through the use of smoke, typically in a smoke house . The combination of heat to dry the food without cooking it, and the addition of the aromatic (phenolic)hydrocarbons from the smoke preserves the food.
Vacuum-packing stores food in a vacuum environment, usually in an air-tight bag or bottle. The vacuum environment strips bacteria of oxygen needed for survival, slowing spoiling.
Canning : food is sealed in a container such as a can or glass jar and heated to kill all living organisms, or at least to ensure that there will be no growth of residual organisms.
Acidic foods should be heated to 100 °C, whereas nonacidic foods should be heated to 121°C. Properly canned foods may not be sterile b/c heating them for the time required might alter the foods’ taste and nutritional value.
Since some of the anaerobic organisms that can grow in cans are from the genus Clostridium , food from a can that is visibly altered, ex. bulged can, should not be eaten .
Oldest forms of preserving meat
Works by removing water from the product
water is required by all microorganisms to grow NO WATER = NO GROWTH
Dehydrate by air drying, heating, or freezing
Example: “Beef Jerky”
Chemicals inhibit microorganism growth
Salting or curing draws moisture from the meat through a process of osmosis.
Nitrates and Nitrites
Add flavor to the product
Improve product shelf life
Develop a pink cured-meat color
All Chemicals added to meat are FDA approved
Works by changing sugar into acid
Acid prevents microorganisms from growing
Tangy flavor and special texture developed
Modified Atmosphere Preservation
MAP – Modified Atmosphere Packaging
Equilibrium Modified Atmosphere
Controlled Atmosphere Packaging
A new process to make food SAFER!!!!
Works by exposing meat to radiant energy
Destroys most (but not all) microorganisms
“ Radura” sign on labels
Irradiated meat is still nutritious
Irradiated meat needs to be COOKED
IRRADIATED MEAT IS SAFE TO EAT!!!!
The 5 Factors in the Curing Process
3 main ingredients to preservation process
Flavor is the primary reason consumers purchase meat more than once
Salt- Predominant flavor in most processed meats
Sugar- Used to reduce the harshness of the salt flavor
Nitrite- Provide a characteristic flavor you recognize as a ham flavor
Smoked- Contains a smoke flavoring rather than being traditionally smoked
Color and Tenderness
Color- If nitrate is used the meat will take on a distinctive red color.
Tenderness- The type of process will affect the tenderness of the meat.
Examples: Jerky the meat is dry and tough
Ham usually fairly tender
When meat products are cooked and smoked, some water and juices are lost, making the product weigh less, thus reducing the product’s value.
Moisture- Helps prevent moisture loss during cooking and smoking
Increased Profits- Adds weight to products increasing the price of the product.
Curing- Used to deliver cure ingredients into the fresh meat prior to curing.
The Curing Process
Increase product yield
Aid in color, texture or flavor development
Increase product shelf-life
Increase process efficiency
Please contact Dr. Elizabeth Boyle or Ryan Timm at (785)532-1247