9.3 Minimal processing techniques

Minimal processing techniques aim to preserve food while keeping it fresh and nutritious. These methods, like modified atmosphere packaging and mild heat treatments, extend shelf life without drastically altering food quality. They're gentler alternatives to traditional processing, maintaining flavor and nutrients.

Combining multiple preservation methods, known as hurdle technology, creates obstacles for microbes. This approach allows for milder treatments while ensuring food safety. From vacuum packaging to refrigeration, these techniques work together to keep food fresh and safe for longer periods.

Packaging Techniques

Modified Atmosphere Packaging (MAP) and Vacuum Packaging

• Modified atmosphere packaging (MAP) involves altering the composition of gases surrounding a food product to extend shelf life and maintain quality
  • Typically involves reducing oxygen levels and increasing carbon dioxide and/or nitrogen levels
  • Can inhibit growth of aerobic microorganisms (mold, bacteria) and reduce oxidation reactions
• Vacuum packaging removes air from the package before sealing, creating an anaerobic environment
  • Inhibits growth of aerobic microorganisms and reduces oxidation reactions
  • Commonly used for meats, cheeses, and dried goods (jerky, nuts)
• Both MAP and vacuum packaging can significantly extend shelf life compared to traditional packaging methods
  • Example: Vacuum-packed meats can last 3-5 times longer than conventionally packaged meats

Sous Vide Cooking and Packaging

• Sous vide is a cooking method where food is sealed in an airtight container (usually a vacuum-sealed bag) and cooked in a temperature-controlled water bath
  • Allows for precise control over cooking temperature and time, resulting in evenly cooked food
  • Helps retain moisture and flavor as food cooks in its own juices
• Sous vide packaging involves vacuum sealing food before cooking
  • Removes air to prevent oxidation and helps food retain shape during cooking
  • Allows for efficient heat transfer from the water bath to the food
• Sous vide can be used for a variety of foods including meats, vegetables, and even desserts
  • Example: Sous vide steak is cooked to a precise temperature for tenderness and juiciness

Temperature Control

Refrigeration and Cold Chain Management

• Refrigeration involves storing foods at low temperatures (usually below 40°F/4°C) to slow down microbial growth and chemical reactions
  • Helps extend shelf life and maintain food safety
  • Different foods require different optimal storage temperatures (e.g., meat vs. produce)
• Cold chain management ensures that temperature-sensitive foods are kept at the proper temperature from production to consumption
  • Involves refrigerated storage, transport, and display
  • Critical for maintaining safety and quality of perishable foods (dairy, meats, frozen foods)
• Proper refrigeration and cold chain management are essential for minimizing food waste and foodborne illness
  • Example: Milk is kept refrigerated from the dairy farm to the grocery store to the consumer's home

Mild Heat Treatment

• Mild heat treatment involves heating foods to temperatures below those used in conventional cooking or pasteurization
  • Usually in the range of 140-180°F (60-82°C)
  • Can inactivate enzymes and reduce microbial loads without significantly altering taste or texture
• Mild heat treatments are often combined with other preservation methods like MAP or refrigeration in hurdle technology
  • Example: Mild heat treatment followed by refrigeration can extend the shelf life of fresh pasta
• Some examples of mild heat treatment include sous vide cooking, thermization (for milk), and pasteurization (for juices)
  • These treatments help improve safety and extend shelf life while maintaining food quality

Preservation Methods

Hurdle Technology and Combination Preservation Methods

• Hurdle technology involves combining multiple preservation methods to create "hurdles" that microorganisms must overcome to grow
  • Each hurdle (e.g., low pH, refrigeration, preservatives) stresses the microbes and makes it more difficult for them to proliferate
  • Hurdles can have additive or synergistic effects in inhibiting microbial growth
• Common hurdles used in combination include:
  • Modified atmosphere packaging to reduce oxygen and increase CO2
  • Vacuum packaging to remove oxygen
  • Refrigeration to slow down microbial growth and chemical reactions
  • Mild heat treatment to reduce microbial loads and inactivate enzymes
  • Preservatives (natural or artificial) to inhibit microbial growth
  • Reduction of water activity (through drying, freezing, or adding solutes)
  • Acidification to lower pH and inhibit bacterial growth
• Hurdle technology allows for the use of milder preservation methods while still ensuring food safety and extending shelf life
  • Example: Vacuum-packaged, mildly heat-treated, and refrigerated deli meats use multiple hurdles to maintain quality and safety