Non-Thermal Food Processing Quiz
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Questions and Answers

Which of the following is NOT a method of non-thermal processing?

  • High Hydrostatic Pressure (HHP)
  • Thermal processing (correct)
  • Ultrasound (US)
  • Pulsed Electric Field (PEF)

    • High Pressure Processing (HPP) can degrade vitamins, flavor, and color molecules.

    False

    What is the main purpose of using Pulsed Electric Field (PEF) in food processing?

    To inactivate pathogenic microorganisms

    High Hydrostatic Pressure (HHP) can apply pressures up to _____ MPa.

    <p>1000</p> Signup and view all the answers

    Match the preservation technique with its benefit:

    <p>High Hydrostatic Pressure (HHP) = Retains sensory qualities and nutritional values Pulsed Electric Field (PEF) = Minimizes energy loss due to heating Ultrasound (US) = Non-thermal processing method High Pressure Processing = Rapid processing times</p> Signup and view all the answers

    What is the typical pressure level used in High Pressure Processing to achieve a tenfold reduction in bacterial cells?

    <p>350MPa for 30min</p> Signup and view all the answers

    Bacterial spores are easily destroyed by High Pressure Processing.

    <p>False</p> Signup and view all the answers

    What is the shelf life of fruit-based chilled HPP products?

    <p>21-28 days</p> Signup and view all the answers

    What is the typical electric field intensity used in PEF treatment?

    <p>20 – 80 kV/cm</p> Signup and view all the answers

    PEF treatment can be applied to any type of food product without restrictions.

    <p>False</p> Signup and view all the answers

    What is the mechanism called that allows cell membranes to develop pores during PEF treatment?

    <p>Electroporation</p> Signup and view all the answers

    The shelf life of raw skim milk treated with PEF was increased to _____ days.

    <p>14</p> Signup and view all the answers

    Match the food item with its corresponding PEF treatment parameters:

    <p>Apple juice = 50 kV/cm, 10 pulses, 2 ms Raw skim milk = 40 kV/cm, 30 pulses, 2 ms</p> Signup and view all the answers

    What was the shelf life increase of apple juice after PEF treatment compared to fresh squeezed juice?

    <p>28 days vs 21 days</p> Signup and view all the answers

    PEF treatment causes significant physical or chemical changes in ascorbic acid or sugars.

    <p>False</p> Signup and view all the answers

    What is the typical duration of the pulses used in PEF treatment?

    <p>Microseconds</p> Signup and view all the answers

    What is a major disadvantage of using ultrasound for sterilization?

    <p>It has limited lethal effect.</p> Signup and view all the answers

    The oscillating magnetic field (OMF) can have a static intensity over time.

    <p>False</p> Signup and view all the answers

    What are free radicals generated during the collapse of bubbles responsible for in the sterilization process?

    <p>Inactivation of bacterial cells by oxidative damage</p> Signup and view all the answers

    OMF treatment for food preservation typically involves a frequency range of _____ kHz.

    <p>5 to 50</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Cavitation = Formation and implosion of small bubbles in a liquid Mano Thermo Sonication = Ultrasound in combination with heat and pressure for sterilization Static Magnetic Field = Magnetic field with constant intensity over time Electric field oscillation = Caused by alternating attraction and repulsion of electrons in a conductor</p> Signup and view all the answers

    What is the primary benefit of treating raw skim milk with 80°C for 6 seconds followed by PEF treatment?

    <p>Increased shelf life</p> Signup and view all the answers

    Electroporation refers to the alteration of membrane permeability in microorganisms.

    <p>True</p> Signup and view all the answers

    List two mechanisms through which pulse light disrupts bacterial cells.

    <p>Photochemical mechanism and Photo thermal mechanism</p> Signup and view all the answers

    Ultrasound waves are defined as energy generated by sound waves of over ______ vibrations per second.

    <p>20,000</p> Signup and view all the answers

    Match the following types of treatment with their main characteristic:

    <p>PEF = Alters membrane permeability Pulse Light = Uses high energy light pulses Ultrasound = Generates high temperatures during implosion Heating = Increases shelf life of milk when combined with PEF</p> Signup and view all the answers

    Which component is NOT a part of the pulse light treatment process?

    <p>Ultrasound generator</p> Signup and view all the answers

    The effectiveness of pulse light treatment does not depend on the intensity of light delivered.

    <p>False</p> Signup and view all the answers

    What is a major limitation of pulse light treatment?

    <p>Low degree of penetration</p> Signup and view all the answers

    Study Notes

    Other Preservation Techniques

    • Non-thermal processing is a promising approach for fruit juice and beverage preservation.
    • Products using non-thermal techniques retain more sensory and nutritional qualities compared to traditionally processed products.
    • Examples include high hydrostatic pressure (HHP), pulsed electric field (PEF), and ultrasound (US).

    High Pressure Processing (HPP)

    • Also known as high hydrostatic pressure (HHP)
    • HHP uses up to 900 MPa to kill microorganisms in food, without degrading vitamins, flavour, or colour.
    • High pressures (up to 1000 MPa) are applied to submerged food packages, distributing pressure evenly.
    • 350 MPa for 30 minutes or 400 MPa for 5 minutes significantly reduces vegetative cells of bacteria, yeasts, or molds.
    • HPP doesn't involve heating, so sensory and nutritional qualities are preserved similar to unprocessed products.
    • Processing times are faster than thermal processing.
    • Bacterial spores are resistant; therefore, products are chilled or refrigerated.
    • Shelf-life varies by product type (e.g., fruit-based chilled products have a shelf-life of 21-28 days, while meat products have a shelf-life of 30-60 days). Meat products may use curing agents to prevent botulism.

    Pulse Electric Field (PEF)

    • Non-thermal pasteurization technique.
    • Used on liquid foods (liquid egg, milk, fruit juices).
    • Main purpose is to inactivate pathogenic microorganisms.
    • Minimizes energy loss associated with heating foods.
    • Superior to traditional heat treatment, as it avoids or greatly reduces detrimental changes in the sensor and physical properties of foods.
    • Involves applying pulses of high voltage (typically between 20-80 kV/cm) to food located between electrodes.
    • Pulses have specific frequency, duration, and intensity.
    • Application is restricted to foods that can withstand high electric fields. PEF treatment chamber consists of at least two electrodes and insulation, creating a volume where food receives pulses. Electrodes are made of inert materials (e.g., titanium).
    • The application of electric fields to biological cells causes a buildup of electrical charges at the cell membrane. The resulting pore formation increases membrane permeability leading to cell content loss or intrusion of external media.
    • Treatment effectiveness depends on the intensity and number of pulses (frequency).
    • Apple juice treated with PEF had a longer shelf life (28 days) compared to fresh squeezed apple juice (21 days).
    • No significant changes in ascorbic acid or sugars were observed.

    Pulse Light

    • Non-thermal method.
    • Three main components: power supply, pulse configuration device, and xenon lamp.
    • Converts high-speed electronic pulses into high-energy light pulses.
    • Uses high-intensity flashes of broad-spectrum light (UV to infrared) at short durations.
    • High energy is delivered to the lamp, producing intense pulses of light focused on the treatment area.
    • Exposing food to this light disrupts bacterial cell membranes.
    • Effectiveness depends on intensity and number of pulses.

    Ultrasound Waves

    • Defined as energy generated by sound waves over 20,000 vibrations per second.
    • Sonic waves with frequencies above human hearing (16-20 kHz).
    • Generated by mechanical vibrations above 18 kHz.
    • During implosion, very high temperatures and pressures are reached inside bubbles.
    • Potentially most useful for sterilizing liquids (e.g., milk and juices).
    • Disadvantages have limited lethal effect and effective if applied with pressure (e.g., Mano Sonication or Mano Thermo Sonication).

    Oscillating Magnetic Field (OMF)

    • Static Magnetic Field (SMF): Constant magnetic field intensity.
    • Food is treated with magnetic pulses (millisecond range) with exposure times of 25 to over 100ms
    • Frequency applied is between 5-50 kHz and field strength is between 5-50 Tesla.
    • Effectiveness is dependent on pulse number and frequency.
    • OMF might loosen bonds between ions and proteins in microorganisms.
    • The effect on microorganisms may be due to the rotating electric field formed by the variable magnetic field.

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    Food Preservation Techniques PDF

    Description

    Test your knowledge on non-thermal food processing methods such as High Pressure Processing (HPP) and Pulsed Electric Field (PEF). This quiz covers various techniques, their purposes, and benefits in preserving food quality while minimizing thermal effects. Perfect for food science students and professionals!

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