Food Preservation Hurdle Technology Quiz

Hurdle Technology

• Hurdle technology is a preservation method combining mild, but reliable preservation factors or techniques.
• It aims to improve product quality and safety.
• It uses gentle, but effective preservation methods.
• Stress factors, known as hurdles, often have a synergistic (enhancing) or additive effect.

pH Scale and Preservation Examples

• A pH scale measures acidity or basicity.
• More acidic foods have a lower pH (1-6).
• More basic foods have a higher pH (8-14).
• Examples:
  • 1 M HCl (Battery Acid): Highly acidic
  • Stomach Acid: Acidic
  • Coke/Vinegar: Acidic
  • Rain Water: Neutral
  • Pure Water: Neutral
  • Baking Soda: Slightly basic
  • Ammonia (household cleaner): Basic
  • 1 M NaOH: Highly basic

Synergistic Effect

• Effective preservation is achieved using several preservatives at low concentrations.
• This surpasses the effectiveness of using a single preservative at high concentrations.
• Microorganisms have multiple targets within the cell – cell membrane, and even DNA.
• Preservatives affect different targets within the microorganism's cell, preventing it from repairing itself.

Hurdle Factors

• Temperature, pH, water activity (Aw), and redox potential (Eh) are common hurdles.
• There are 50 different hurdles used in food preservation.
• Other hurdles include ultrahigh-pressure treatment, modified atmosphere packaging (MAP), edible coatings/films, ethanol, and bacteriocins.

Homeostasis and Hurdles

• Homeostasis is a microorganism's ability to maintain a stable and uniform internal environment.
• Microorganisms have mechanisms to resist stress factors such as pH, water activity (Aw), and temperature.
• Hurdles disrupt homeostatic mechanisms that make growth impossible.
• Several combined hurdles used simultaneously are more effective for food preservation.

Microorganism Stress Responses

• Microorganisms respond to stress through active processes which expend energy.
• They use mechanisms such as transporting protons across the cell membrane and maintaining high cytoplasmic concentrations to keep their internal environment stable.
• Disrupting this homeostasis is key to food preservation by the application of hurdles.
• Effective application of hurdle technology relies upon metabolic exhaustion of the microorganism.

Principle of Hurdle Technology

• Preservative factors disrupt microorganism homeostasis.
• Microorganisms aren't able to adapt effectively to multiple hurdles.
• Preservative factors prevent microorganisms from multiplying and causing food to spoil.
• Combinations of different hurdles (temperature, water activity, pH) create significant effects on microbial stability.

Water Activity (Aw)

• Water activity (aw) is a measure of the energy status of water in a system (qualitative).
• It is an intensive property that does not depend on the amount of material—differentiating it from moisture content.
• Water activity is crucial for microbial stability.

Intensive and Extensive Properties

• Intensive properties, like aw and temperature, don't depend on the amount of substance.
• Extensive properties, like weight and volume, depend on the amount of substance.

Examples of Foods Preserved by Hurdle Technology

• Salami-type fermented sausages: Combinations of salt, nitrate, Eh, pH, and aw.
• Smoked products: Heat, reduced aw, salt, and antimicrobial chemicals.
• Jam: Heat, high acidity, high sugar content, reduced aw.
• Pickles: Salt, acetic acid, heat, and chemical preservatives (e.g., benzoate, sorbate).

Hurdle Technology Applications and Examples

• Thermal processing (blanching, pasteurization, or canning), combined with antimicrobial agents like sodium benzoate or vanillin.
• High pressure combined with biopreservative sources.
• Irradiation with preservatives like organic acids, bacteriocins, or natural antioxidants.
• Modified atmosphere packaging (MAP) combined with high-pressure processing and irradiation.

Industrial Applications of Hurdle Technology

• Minimally processed fruits and vegetables using temperature control, antioxidant solutions, and chlorinated water.
• Combining chilling, disinfection, and modified atmosphere packaging (MAP).
• Combining UV light with chemical disinfectants and MAP.
• Combined use of chlorinated water and UV light for fresh cut fruit and vegetable disinfection.
• Using UV light in combination with mild heat treatment to inactivate harmful fungi in products like strawberries and sweet cherries.

Combined Methods for Preserving Tropical Fruits

• Different combinations of blanching methods, temperature, and preservatives are examined to discover optimal preservation methods.

Intermediate Moisture Foods

• Modifications to traditional intermediate-moisture (IMF) foods result in high moisture stable foods.
• Ease of preparation, storage without refrigeration, and energy efficiency are advantages over conventional preservation methods.
• Disadvantages: Too high sugar content and potential health hazard from additive use.

Hurdle Technology Summary

• Increased moisture content and aw while reducing sugar and salt is a key application to ensure microbial stability during ambient storage.
• Hurdles such as mild heat, reduced aw, low pH, preservatives, anti-browning agents, and anti-softening agents are used.

Significance of Hurdle Technology

• Improved product quality and enhanced safety.
• Reduced costs in terms of money, energy, and other resources saved due to more effective preservation.
• Maintenance of stable foods with high sensory and nutritious qualities due to minimal processing.
• Preserves the integrity of foods, especially fruits.
• Applicability to both large and small food industries across the manufacture of new products.