Control by Novel Processing Technologies ◾ 515
microorganisms. Various aspects of this method, including applications in food, have been studied. A short review of the method is presented in the section on pulsed electric fields in this chapter. PEF has also been used effectively together with high hydrostatic pressure (HHP) technology 11
or ultraviolet (UV) radiation as a hurdle approach for microbial inactivation. 12
High-Pressure Processing 13,14
High-pressure processing (HPP), also known as high hydrostatic pressure (HHP), is a nonthermal method involving pressurization of a packaged food in a water-filled, closed chamber for a
short duration to inactivate microorganisms. A liquid food can be pressurized directly. In addition to an antimicrobial effect, it has many other food applications. The method has generated
a great interest, and several foods have already been commercially produced. A review of the
current status of the method has been presented in the section on hydrostatic pressure processing
in this chapter.
Pulsed Light Technology 5,15
This is a nonthermal method in which microorganisms on the surface of food (usually in a transparent package) are inactivated by high-energy light pulses. Light pulses in the wavelengths of
170–2600 nm are used for a very short duration (≤0.01 seconds). Processing units have been developed in which electric energy can be stored in a capacitor over a long period, which then can be
released in a shorter time to produce an antimicrobial effect. The antimicrobial effect is produced
through the action on nucleic acids (especially in the UV range), proteins, membranes, and other
cellular components. The antimicrobial effectiveness of the process has been studied on the food
contact surface, the packaging materials, and the surface of various foods, including cheeses, processed meat products, bakery products, and fishery products. Following treatment, the products
retained acceptance qualities during extended shelf life.
Oscillating Magnetic Fields 5,16
In this nonthermal method, a food, sealed in a plastic bag, is exposed to oscillating magnetic
fields (OMF) (<500 kHz) for a duration to receive 1–100 pulses over a short period (≤100 ms).
Limited studies showed that microbial inactivation is two to three log cycles, but the results were
inconsistent. Some studies have been conducted using milk, yogurt, orange juice, and dough.
The antimicrobial effect is produced from the damages in the DNA during exposure to the magnetic field.
Ultrasound 17,18
Lysis of microbial cells by sonication forms the basis of the use of ultrasound to inactivate
microorganisms in foods. The method consists of generating high-frequency sound waves in
the test materials. The antimicrobial effect of ultrasound is attributed to intracellular cavitation that disrupts the cellular structures and functional components. Limited studies revealed
that the antimicrobial effect of ultrasound in food is rather low. However, it can be enhanced
by combining ultrasound with heat above 50°C (122°F). In addition to the antimicrobial
effect, ultrasound has been studied as a means to determine texture, viscosity, thickness, and
composition of different foods.
microorganisms. Various aspects of this method, including applications in food, have been studied. A short review of the method is presented in the section on pulsed electric fields in this chapter. PEF has also been used effectively together with high hydrostatic pressure (HHP) technology 11
or ultraviolet (UV) radiation as a hurdle approach for microbial inactivation. 12
High-Pressure Processing 13,14
High-pressure processing (HPP), also known as high hydrostatic pressure (HHP), is a nonthermal method involving pressurization of a packaged food in a water-filled, closed chamber for a
short duration to inactivate microorganisms. A liquid food can be pressurized directly. In addition to an antimicrobial effect, it has many other food applications. The method has generated
a great interest, and several foods have already been commercially produced. A review of the
current status of the method has been presented in the section on hydrostatic pressure processing
in this chapter.
Pulsed Light Technology 5,15
This is a nonthermal method in which microorganisms on the surface of food (usually in a transparent package) are inactivated by high-energy light pulses. Light pulses in the wavelengths of
170–2600 nm are used for a very short duration (≤0.01 seconds). Processing units have been developed in which electric energy can be stored in a capacitor over a long period, which then can be
released in a shorter time to produce an antimicrobial effect. The antimicrobial effect is produced
through the action on nucleic acids (especially in the UV range), proteins, membranes, and other
cellular components. The antimicrobial effectiveness of the process has been studied on the food
contact surface, the packaging materials, and the surface of various foods, including cheeses, processed meat products, bakery products, and fishery products. Following treatment, the products
retained acceptance qualities during extended shelf life.
Oscillating Magnetic Fields 5,16
In this nonthermal method, a food, sealed in a plastic bag, is exposed to oscillating magnetic
fields (OMF) (<500 kHz) for a duration to receive 1–100 pulses over a short period (≤100 ms).
Limited studies showed that microbial inactivation is two to three log cycles, but the results were
inconsistent. Some studies have been conducted using milk, yogurt, orange juice, and dough.
The antimicrobial effect is produced from the damages in the DNA during exposure to the magnetic field.
Ultrasound 17,18
Lysis of microbial cells by sonication forms the basis of the use of ultrasound to inactivate
microorganisms in foods. The method consists of generating high-frequency sound waves in
the test materials. The antimicrobial effect of ultrasound is attributed to intracellular cavitation that disrupts the cellular structures and functional components. Limited studies revealed
that the antimicrobial effect of ultrasound in food is rather low. However, it can be enhanced
by combining ultrasound with heat above 50°C (122°F). In addition to the antimicrobial
effect, ultrasound has been studied as a means to determine texture, viscosity, thickness, and
composition of different foods.