High Pressure Food Processing

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Questions and Answers

What was the original intention of Bert Hite when he created an HP unit?

To enhance the physical properties of food

To extract functional ingredients from foodstuffs

To pasteurize food products such as milk (correct)

To preserve food through thermal treatments

What is a major advantage of HP processing over traditional thermal treatments?

It is a slower process

It maintains the natural attributes of foods (correct)

It increases the microbiological load of foods

It reduces the quality of foods

How is pressure distributed through the treated food sample in HP processing?

Only on the surface of the food

Unevenly and slowly

Evenly and instantaneously (correct)

Depending on the type of food

What is a potential application of HP technology in food processing?

Modifying the physicochemical properties of functional ingredients Signup and view all the answers

What is the effect of pressurization on the temperature of the product in HP processing?

The temperature increases due to adiabatic heating Signup and view all the answers

What determines the magnitude of the temperature increase during pressurization?

The pressure medium and pressurization rate Signup and view all the answers

What is one of the benefits of HP processing in preserving food?

It reduces the enzymatic activity of foods Signup and view all the answers

What is a potential benefit of HP processing for food manufacturers?

It enhances several food processes Signup and view all the answers

What is the effect of rapid freezing rates on ice crystal formation?

Formation of small ice crystals Signup and view all the answers

What is the effect of high pressure on the phase change temperature of water?

It decreases the phase change temperature of water Signup and view all the answers

What is the primary advantage of HP-assisted thawing?

Limiting microbial growth Signup and view all the answers

What is the primary mechanism of HP freezing?

Decreasing the melting point of ice Signup and view all the answers

What is the primary application of HP in food storage?

Non-frozen storage Signup and view all the answers

What is the primary advantage of HP extraction?

Isolating bioactive components from natural materials Signup and view all the answers

What is the effect of slow freezing rates on ice crystals?

Formation of large ice crystals Signup and view all the answers

What is the primary difference between HP thawing and conventional thawing?

HP thawing is faster than conventional thawing Signup and view all the answers

What is the primary mechanism by which ultrasound inactivates microbial cells?

Cells are disrupted by the shock waves generated by cavitation Signup and view all the answers

What is the result of the rapid condensation of gas bubbles in a liquid medium during sonication?

Creation of shock waves Signup and view all the answers

What is the effect of increasing the pressure during sonication, as in mano-sonication?

Reduced treatment time Signup and view all the answers

What is the role of ultrasonic waves in the inactivation of enzymes?

Denaturation of enzyme proteins Signup and view all the answers

What is the effect of the amplitude of ultrasonic waves on microbial killing?

Increased amplitude increases microbial killing Signup and view all the answers

What is the effect of the volume of the object being processed on sonication?

Larger volumes increase treatment time Signup and view all the answers

What is the effect of temperature on the inactivation of enzymes using ultrasound?

Higher temperatures increase enzyme inactivation Signup and view all the answers

What is the result of the formation of gas bubbles during sonication?

Increased pressure around the bubbles Signup and view all the answers

What is the primary function of a product-handling system in HP processing?

To transfer the product to and from the pressure chamber Signup and view all the answers

What is the range of pressure that generally decreases the growth rate of microorganisms?

10-50 MPa Signup and view all the answers

What is the primary site for pressure-induced microbial inactivation?

Cell membrane Signup and view all the answers

What is the characteristic of gram-negative bacteria in terms of pressure resistance?

They are less pressure-resistant than gram-positive bacteria Signup and view all the answers

What is the effect of HP on the cell membrane of microorganisms?

It causes a phase transition of the membrane lipid bilayer Signup and view all the answers

What is the major challenge to the food processing and food safety industry?

Bacterial spores Signup and view all the answers

What is the result of HP treatment on microorganisms under proper conditions?

Inactivation of both pathogenic and spoilage microorganisms Signup and view all the answers

What is the effect of HP on the structure of bacterial spores?

It has no effect on the spore coat Signup and view all the answers

What happens to cavitation bubbles due to the extreme local increase in pressure and temperature during ultrasound?

They collapse Signup and view all the answers

What is affected by shock waves and strong stress in protein during ultrasound?

Secondary and tertiary structure Signup and view all the answers

What is produced during ultrasound treatment of water?

Hydroxyl and hydrogen free radicals Signup and view all the answers

What is the benefit of using high-frequency power ultrasound to clean wine barrels?

Reducing the levels of yeast cells Signup and view all the answers

What is the advantage of using ultrasound in drying?

It reduces the processing time Signup and view all the answers

What is the effect of sonication before spray drying?

It controls the final exit droplet size and distribution Signup and view all the answers

What is a factor that influences the drop size produced in spray drying?

The frequency of vibration Signup and view all the answers

What is a characteristic of ultrasound-treated samples?

Higher porosity Signup and view all the answers

Study Notes

High-Pressure (HP) Processing

Over a century ago, Bert Hite created an HP unit to pasteurize food products such as milk, and since then, studies have been conducted on the effects of HP on foods.
HP processing is a promising alternative to thermal treatments, minimizing processing effects on quality properties.
The potential of HP to reduce microbiological load and enzymatic activity while maintaining natural attributes of foods led to its rapid adoption.

Description of the Process

Pressure is evenly and instantaneously transmitted throughout the sample, affecting all food parts without over-treating.
Proper HP treatment does not reduce food quality.

Advantages of Adoption of this Novel Technology

Reduces microbiological load and enzymatic activity of foods while maintaining their natural attributes.
Enhances several food processes (e.g., extraction, freezing, thawing).
Modifies the physicochemical properties of functional ingredients in some foodstuffs.

Current Commercial Status of HP Processing

HP processing can be applied to a wide range of foods, including meat-based products, precooked dishes, fruit, vegetables, and juices.
HP processing has been commercialized in many regions, including Asia, North America, Europe, and Australia.

Effect of HP on Microorganisms

A moderate level of pressure (10-50 MPa) decreases the growth rate of microorganisms, while a higher pressure level leads to microbial inactivation.
HP treatment under proper conditions can result in the inactivation of pathogenic and spoilage microorganisms in food products.
The primary site for pressure-induced microbial inactivation is the cell membrane.

Effect of HP on Bacterial Spores

Bacterial spores represent the greatest food processing and food safety challenges to the industry.
The thickness and structure of the bacterial spore coat make it resistant to various stresses, including pressure.

HP Freezing and Thawing

HP has a profound effect on the phase change temperature of water, allowing for rapid freezing and thawing.
Rapid freezing rate results in a fine ice structure, with intensive nucleation and the formation of large numbers of small ice crystals, which causes less damage to the product's structure.
HP-assisted thawing has proved to be a promising technology for food thawing processes, limiting microbial growth, and decreasing drip loss.

HP Non-Frozen Storage

Food products can be stored in a non-frozen state without ice crystal formation utilizing the application of HP.

HP Extraction

HP extraction is useful in isolating bioactive components from various raw materials, particularly natural materials.

Ultrasound Processing

Ultrasound is an effective method in microbial kill, enzyme inactivation, and as a processing aid in cleaning and drying.
Ultrasound waves induce intermolecular forces within the food medium and microbial cells, leading to cell wall rupture, cell lysis, and inactivation.

Ultrasound-Assisted Thawing

Ultrasound-assisted thawing has proved to be a promising technology for food thawing processes, limiting microbial growth, and decreasing drip loss.

Ultrasound-Assisted Drying

Ultrasound-assisted drying accelerates the processing time, resulting in higher shrinkage, lower density, shorter drying times, and higher porosity than untreated samples.

Ultrasound-Assisted Spray Drying

Sonication before spray drying affects the viscosity and distribution of particles, introducing the ability to control the final exit droplet size and distribution.

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Description

Learn about high pressure processing as an alternative to thermal treatments in food preservation, its history, and effects on food quality.